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Main
Date: 11 May 2007 13:32:51
From:
Subject: mild cracks in right crank
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I noticed two very small cracks at the junction between the spider
arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
says,
"The trailing spider leg adjacent to the crank generally has a
thin web that connects it to the more rigid shaft of the crank, while
the three preceding legs are more flexible, stress is concentrated at
this web. These cracks are relatively benign because they are easily
seen and rarely progress to failure."
Should I file and then sand the cracks out before they get worse, or
leave them? Does anyone have any experience with this? The cranks are
NR.
Thanks
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Date: 14 May 2007 10:38:39
From: Jay Beattie
Subject: Re: mild cracks in right crank
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On May 14, 10:16 am, Jay Beattie <jbeat...@lindsayhart.com > wrote:
> On May 11, 1:32 pm, pianofigh...@gmail.com wrote:
>
> > I noticed two very small cracks at the junction between the spider
> > arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
> > says,
> > "The trailing spider leg adjacent to the crank generally has a
> > thin web that connects it to the more rigid shaft of the crank, while
> > the three preceding legs are more flexible, stress is concentrated at
> > this web. These cracks are relatively benign because they are easily
> > seen and rarely progress to failure."
> > Should I file and then sand the cracks out before they get worse, or
> > leave them? Does anyone have any experience with this? The cranks are
> > NR.
>
> Here is an interesting picture:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>
> This of course is an old NR crank which were notorious for failing. I
> had a couple break just like this one, and several others above the
> pedal eye. I think the principal failure mode for Jobst was through
> the pedal eye, and thus his conical-washer fix. According to the
> author of this page, the crack initiated at the crotch in the spider
> between the arm and the trailing leg. I have not heard of modern
> cranks failing in the same way, although one always wants to keep an
> eye on cracks. Clicking and snapping sounds also can be a cue, usually
> a very late one. -- Jay Beattie.
Hate to post on myself, but I shouldn't have said the author said the
crack started at the trailing leg. He just said between the spider and
the crank arm. -- Jay Beattie.
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Date: 14 May 2007 10:16:54
From: Jay Beattie
Subject: Re: mild cracks in right crank
|
On May 11, 1:32 pm, pianofigh...@gmail.com wrote:
> I noticed two very small cracks at the junction between the spider
> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
> says,
> "The trailing spider leg adjacent to the crank generally has a
> thin web that connects it to the more rigid shaft of the crank, while
> the three preceding legs are more flexible, stress is concentrated at
> this web. These cracks are relatively benign because they are easily
> seen and rarely progress to failure."
> Should I file and then sand the cracks out before they get worse, or
> leave them? Does anyone have any experience with this? The cranks are
> NR.
>
Here is an interesting picture: http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
This of course is an old NR crank which were notorious for failing. I
had a couple break just like this one, and several others above the
pedal eye. I think the principal failure mode for Jobst was through
the pedal eye, and thus his conical-washer fix. According to the
author of this page, the crack initiated at the crotch in the spider
between the arm and the trailing leg. I have not heard of modern
cranks failing in the same way, although one always wants to keep an
eye on cracks. Clicking and snapping sounds also can be a cue, usually
a very late one. -- Jay Beattie.
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Date: 14 May 2007 17:39:55
From: _
Subject: Re: mild cracks in right crank
|
On 14 May 2007 10:16:54 -0700, Jay Beattie wrote:
> On May 11, 1:32 pm, pianofigh...@gmail.com wrote:
>> I noticed two very small cracks at the junction between the spider
>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>> says,
>> "The trailing spider leg adjacent to the crank generally has a
>> thin web that connects it to the more rigid shaft of the crank, while
>> the three preceding legs are more flexible, stress is concentrated at
>> this web. These cracks are relatively benign because they are easily
>> seen and rarely progress to failure."
>> Should I file and then sand the cracks out before they get worse, or
>> leave them? Does anyone have any experience with this? The cranks are
>> NR.
>>
>
> Here is an interesting picture: http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>
> This of course is an old NR crank which were notorious for failing. I
> had a couple break just like this one, and several others above the
> pedal eye. I think the principal failure mode for Jobst was through
> the pedal eye, and thus his conical-washer fix. According to the
> author of this page, the crack initiated at the crotch in the spider
> between the arm and the trailing leg. I have not heard of modern
> cranks failing in the same way, although one always wants to keep an
> eye on cracks. Clicking and snapping sounds also can be a cue, usually
> a very late one. -- Jay Beattie.
The last part is interesting (emphasis added):
"This unfortunate incident may have been prevented only by very close
visual inspection or *dye penetrant* testing on the component during the
relatively short crack propagation phase."
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Date: 14 May 2007 20:02:49
From: jim beam
Subject: Re: mild cracks in right crank
|
_ wrote:
> On 14 May 2007 10:16:54 -0700, Jay Beattie wrote:
>
>> On May 11, 1:32 pm, pianofigh...@gmail.com wrote:
>>> I noticed two very small cracks at the junction between the spider
>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>> says,
>>> "The trailing spider leg adjacent to the crank generally has a
>>> thin web that connects it to the more rigid shaft of the crank, while
>>> the three preceding legs are more flexible, stress is concentrated at
>>> this web. These cracks are relatively benign because they are easily
>>> seen and rarely progress to failure."
>>> Should I file and then sand the cracks out before they get worse, or
>>> leave them? Does anyone have any experience with this? The cranks are
>>> NR.
>>>
>> Here is an interesting picture: http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>
>> This of course is an old NR crank which were notorious for failing. I
>> had a couple break just like this one, and several others above the
>> pedal eye. I think the principal failure mode for Jobst was through
>> the pedal eye, and thus his conical-washer fix. According to the
>> author of this page, the crack initiated at the crotch in the spider
>> between the arm and the trailing leg. I have not heard of modern
>> cranks failing in the same way, although one always wants to keep an
>> eye on cracks. Clicking and snapping sounds also can be a cue, usually
>> a very late one. -- Jay Beattie.
>
> The last part is interesting (emphasis added):
>
> "This unfortunate incident may have been prevented only by very close
> visual inspection or *dye penetrant* testing on the component during the
> relatively short crack propagation phase."
and that's what dye penetrant testing was developed for - to tell you if
cracks are present. doesn't tell you /anything/ about how they got to
be there.
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Date: 14 May 2007 00:33:09
From: Gary Young
Subject: Re: mild cracks in right crank
|
On Sun, 13 May 2007 21:53:19 -0700, jim beam wrote:
> Gary Young wrote:
>
> <snip endless repetition on which absolutely /no/ progress seems to be
> being made>
>
In other words, you say that anodizing can cause fatigue, but offer no
explanation of how it can happen, leaving Jobst's explanation as the only
one on the table. Is it any surprise that I don't think you know what
you're talking about?
>>
>> Even more naive would be to accept the word of an anonymous internet crank
>> over that of an engineer.
>
> i've asked you this before but you never answered. what would you think
> of jobst's writings if he didn't /tell/ you he was an engineer?
I don't recall the question, but I don't think I've left much doubt that
I'm impressed by his analyses.
> particularly in view of fundamental mistake?
What fundamental mistake? In any event, in judging between the two of you,
I would also have to consider your many fundamental mistakes, such as not
understanding boundary lubrication and not knowing about creep in
polymers. That's not to mention your many errors of fundamental logic and
your habit of weaving and dodging in the face of criticism.
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Date: 13 May 2007 23:47:23
From: Gary Young
Subject: Re: mild cracks in right crank
|
On Sun, 13 May 2007 20:42:02 -0700, jim beam wrote:
<snip >
>> You assert that it can happen, but you have no idea by what mechanism
>> it happens?
>
> no gary, i'm saying you can't presume any damned thing unless you bother
> to do the analysis, with the correct tools and know that you're looking
> at! otherwise "opinion" may as well come from the psychic hotline for
> all the value it has.
>
Let me be more explicit. Ordinarily, people say that something "can happen"
if (1) they've actually seen it, (2) they've heard reliable reports
about it, or (3) they have in mind some mechanism that makes it plausible
that it could happen.
You've said that anodizing CAN cause reduced fatigue life (though not in
rims).
Have you seen examples in which anodizing led to fatigue? If so,
what was the mechanism? (I'm assuming it wasn't anodizing cracks
propagating into the aluminum, because you've ruled that out on general
grounds.)
If you've heard reliable reports, what was the mechanism discussed in
those reports?
If you haven't actually seen or heard of it happening, what is the
mechanism you have in mind by which you think it CAN happen? Or were you
simply making a wild guess?
These questions are very pertinent to the discussion at hand. If you can
explain how anodizing causes cracking under some circumstances but that
those circumstances don't obtain in the case of aluminum rims, then you
will go a long way toward answering your critics who point to the many
engineering references to cracking caused by anodizing.
>> In other words, you have no idea what you're
talking about. Except of
>> course, "it does when it does, it doesn't when it doesn't."
>
> no, it's a statement of reality! sheesh. does your dentist know why
> your tooth is aching unless they inspect, analyze and know what they're
> doing?
>
>
If I asked him, What might be causing this?, I would expect him to be able
to say, "It might be this, or it might be that, or it might be the other,
but I won't know for sure until I examine you." If he couldn't even
enumerate at least some of the alternatives, I would seek another dentist.
You've said that there is a way other than Jobst's explanation by which
anodizing reduces fatigue life in aluminum. Yet you seem unable to say
what that alternative way is.
Unless you can explain what the alternative mechanism is, I'm still
betting you don't know what you're talking about.
>>> just because something's anodized doesn't mean it fails. cranks,
>>> handlebars, brakes, seat posts, stems - all are anodized, but none are
>>> subject to "tension as high as the [insert component name here] can
>>> bear". reality is, anodizing /prevents/ failure because it prevents
>>> corrosion which cause surface defects which can initiate fatigue.
>>
>> And cracks in the anodizing expose the underlying aluminum to corrosion
>> -- a google search will show you references to that as well.
>
> it can, but the extent of exposure is limited. accepting underinformed
> presumption that anodizing is "cause" is somewhat naive.
Even more naive would be to accept the word of an anonymous internet crank
over that of an engineer.
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Date: 13 May 2007 21:53:19
From: jim beam
Subject: Re: mild cracks in right crank
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Gary Young wrote:
<snip endless repetition on which absolutely /no/ progress seems to be
being made >
>
> Even more naive would be to accept the word of an anonymous internet crank
> over that of an engineer.
i've asked you this before but you never answered. what would you think
of jobst's writings if he didn't /tell/ you he was an engineer?
particularly in view of fundamental mistake?
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Date: 14 May 2007 09:08:06
From: Tim McNamara
Subject: Re: mild cracks in right crank
|
In article <yYadnZ43Vv7ddtrbnZ2dnUVZ_vamnZ2d@speakeasy.net >,
jim beam <spamvortex@bad.example.net > wrote:
> <snip endless repetition on which absolutely /no/ progress seems to
> be being made>
That would be because you can't frame a coherent argument and cannot
back many of your claims up with facts, so instead you resort to
mulishness, insults and invective.
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Date: 13 May 2007 22:22:57
From: Gary Young
Subject: Re: mild cracks in right crank
|
On Sun, 13 May 2007 17:32:22 -0700, jim beam wrote:
> Gary Young wrote:
>> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
>>
>>> Gary Young wrote:
>>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>>>
>>>>> Gary Young wrote:
>>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>>>
>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>>>>>>> says,
>>>>>>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>>>>>>> NR.
>>>>>>>>>>>>>> Thanks
>>>>>>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>>>>>>> enjoy your flight.
>>>>>>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>>>>>>> where. definitely not in a root.
>>>>>>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>>>>>>> panel.
>>>>>>>>>>> you forget - there's different safety criteria for the military. and
>>>>>>>>>>> the equipment is operated on the bleeding edge.
>>>>>>>>>> The safety criteria for the military is more strict than the civilian
>>>>>>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>>>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>>>>>>> all.
>>>>>>>>>>>> Small
>>>>>>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>>>>>>> from the news, seldom result in wings coming off.
>>>>>>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>>>>>>> aviation wrenches do on aircraft.
>>>>>>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>>>>>>> they progress into this kind of failure - not something to ignore.
>>>>>>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>>>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>>>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>>>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>>>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>>>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>>>>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>>>>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>>>>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>>>>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>>>>>>> 100,000 hours, it's not.
>>>>>>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>>>>>>> common place, it is not. Milspec aircraft maintenance is much more
>>>>>>>> rigorous than civilian. Military aircraft, with service lives measured
>>>>>>>> in decades, also have logbooks with aircraft hours measured in the
>>>>>>>> many thousands. In modern combat, just 'keeping them flying' at any
>>>>>>>> cost are the things of John Wayne movies, not reality. A poorly
>>>>>>>> maintained A/C in combat is much more likely to get the aircrew killed
>>>>>>>> and not kill the bad guy than a well maintained one. Done with this
>>>>>>>> thread..you are too eager to argue, this thread along with the hard
>>>>>>>> anodized thread. I imagine you sitting at your keyboard
>>>>>>>> shouting...adios.
>>>>>>> with the greatest of respect, i used to - oh, what's the point.
>>>>>>>
>>>>>>>>> returning to the crank, filing the surface to make the cracks invisible
>>>>>>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>>>>>>> the solution is replacement, pure and simple. you see these cranks at
>>>>>>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>>>>>>> and ride, go ahead. i think recommending their continued use to others
>>>>>>>>> is reckless and irresponsible.
>>>>>>> i still stand by that - cracked equipment is going to fail. there is no
>>>>>>> "if", simply "when".
>>>>>> And thus cracked anodizing leads to rim failure. If not, why not?
>>>>> er, because cracked anodizing is not cracked aluminum...
>>>> er, in the "Mavic Open Pro" thread, you've conceded that anodizing reduces
>>>> the fatigue life of aluminum.
>>> you're putting words into my mouth - i said it /can/, not that it
>>> /does/. there is a distinction. just like bearings /can/ false
>>> brinell. it doesn't mean that they /do/.
>>>
>>>> How does that happen if not by anodizing
>>>> cracks propagating into the underlying aluminum?
>>> because cracked anodizing is not cracked aluminum. assuming that
>>> because something /can/ means something /does/ is the fundamental
>>> mistake jobst makes repeatedly.
>>
>> When anodizing cracks DO contribute to a reduced fatigue life of aluminum,
>> how do they do so? Or is it now your position that anodizing CAN reduce
>> the fatigue life of aluminum, but never does so in actual fact?
>
> simply, it does when it does, it doesn't when it doesn't. you look at
> the failure - that's analysis.
>
You assert that it can happen, but you have no idea by what mechanism it
happens? In other words, you have no idea what you're talking about.
Except of course, "it does when it does, it doesn't when it doesn't."
> just because something's anodized doesn't mean it fails. cranks,
> handlebars, brakes, seat posts, stems - all are anodized, but none are
> subject to "tension as high as the [insert component name here] can
> bear". reality is, anodizing /prevents/ failure because it prevents
> corrosion which cause surface defects which can initiate fatigue.
And cracks in the anodizing expose the underlying aluminum to corrosion --
a google search will show you references to that as well.
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Date: 14 May 2007 03:52:12
From:
Subject: Re: mild cracks in right crank
|
Gary Young <garyyoung3@gmail.com > writes:
> On Sun, 13 May 2007 17:32:22 -0700, jim beam wrote:
>> Gary Young wrote:
>>> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
>>>> Gary Young wrote:
>>>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>>>>> Gary Young wrote:
>>>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
This is ridiculous. Please omit all citations but the first
reference. The others have all been cited in earlier responses. The
response is only the most recent author. This is not a history
course. Just leave the >>'s as they are. No one wants to know who
said the earlier things, and if they do, the history is there in the
newsgroup.
>>>>>>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>>>>>>> I noticed two very small cracks at the junction
>>>>>>>>>>>>>>> between the spider arms and the crank, no more than a
>>>>>>>>>>>>>>> 1/16" to 1/8" in length. Jobst says:
# The trailing spider leg adjacent to the crank generally has a thin
# web that connects it to the more rigid shaft of the crank, while the
# three preceding legs are more flexible, stress is concentrated at
# this web. These cracks are relatively benign because they are easily
# seen and rarely progress to failure."
>>> When anodizing cracks DO contribute to a reduced fatigue life of
>>> aluminum, how do they do so? Or is it now your position that
>>> anodizing CAN reduce the fatigue life of aluminum, but never does
>>> so in actual fact?
>> simply, it does when it does, it doesn't when it doesn't. you look
>> at the failure - that's analysis.
> You assert that it can happen, but you have no idea by what
> mechanism it happens? In other words, you have no idea what you're
> talking about. Except of course, "it does when it does, it doesn't
> when it doesn't."
>> just because something's anodized doesn't mean it fails. cranks,
>> handlebars, brakes, seat posts, stems - all are anodized, but none
>> are subject to "tension as high as the [insert component name here]
>> can bear". reality is, anodizing /prevents/ failure because it
>> prevents corrosion which cause surface defects which can initiate
>> fatigue.
> And cracks in the anodizing expose the underlying aluminum to
> corrosion -- a google search will show you references to that as
> well.
That is not the principal cause of failure. Recall having skinned
your knee and developing a scab on the wound. If you flex the knee in
a way that stresses the scab, which in effect is a hard coating on the
skin and flesh, it will crack and bleed. That the substructure is
broken by the hard skin is apparent from bleeding. Unfortunately
aluminum doesn't bleed, but it reacts the same, anodizing being many
times harder and more brittle than aluminum.
Jobst Brandt
|
| | | |
Date: 15 May 2007 05:18:49
From: Michael Press
Subject: Re: mild cracks in right crank
|
In article <4647dcec$0$14082$742ec2ed@news.sonic.net >,
jobst.brandt@stanfordalumni.org wrote:
> Gary Young <garyyoung3@gmail.com> writes:
> > On Sun, 13 May 2007 17:32:22 -0700, jim beam wrote:
> >> Gary Young wrote:
> >>> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
> >>>> Gary Young wrote:
> >>>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
> >>>>>> Gary Young wrote:
> >>>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
> >>>>>>>> Qui si parla Campagnolo wrote:
> >>>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
> >>>>>>>>>> Qui si parla Campagnolo wrote:
> >>>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
> >>>>>>>>>>>> Qui si parla Campagnolo wrote:
> >>>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>
> This is ridiculous. Please omit all citations but the first
> reference. The others have all been cited in earlier responses. The
> response is only the most recent author. This is not a history
> course. Just leave the >>'s as they are. No one wants to know who
> said the earlier things, and if they do, the history is there in the
> newsgroup.
I disagree. Leave in all attribution lines so we know who said what.
When all of a poster's text is excised the associated
attribution line can be removed. In some cases this could take
so much care that it may be as well to leave it in.
A reason such as ` This is not a history course'
is no reason at all, but an expression of disapproval.
So noted: you disapprove.
--
Michael Press
|
| | | | |
Date: 16 May 2007 07:54:15
From: Peter Cole
Subject: Re: mild cracks in right crank
|
Michael Press wrote:
> In article <4647dcec$0$14082$742ec2ed@news.sonic.net>,
> jobst.brandt@stanfordalumni.org wrote:
>
>> Gary Young <garyyoung3@gmail.com> writes:
>>> On Sun, 13 May 2007 17:32:22 -0700, jim beam wrote:
>>>> Gary Young wrote:
>>>>> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
>>>>>> Gary Young wrote:
>>>>>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>>>>>>> Gary Young wrote:
>>>>>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>> This is ridiculous. Please omit all citations but the first
>> reference. The others have all been cited in earlier responses. The
>> response is only the most recent author. This is not a history
>> course. Just leave the >>'s as they are. No one wants to know who
>> said the earlier things, and if they do, the history is there in the
>> newsgroup.
>
> I disagree. Leave in all attribution lines so we know who said what.
> When all of a poster's text is excised the associated
> attribution line can be removed. In some cases this could take
> so much care that it may be as well to leave it in.
> A reason such as ` This is not a history course'
> is no reason at all, but an expression of disapproval.
> So noted: you disapprove.
>
Opinions vary, I stop reading threads like this, just too much work.
|
| | | |
Date: 13 May 2007 21:03:22
From: jim beam
Subject: Re: mild cracks in right crank
|
jobst.brandt@stanfordalumni.org wrote:
> Gary Young <garyyoung3@gmail.com> writes:
>> On Sun, 13 May 2007 17:32:22 -0700, jim beam wrote:
>>> Gary Young wrote:
>>>> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
>>>>> Gary Young wrote:
>>>>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>>>>>> Gary Young wrote:
>>>>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>
> This is ridiculous. Please omit all citations but the first
> reference. The others have all been cited in earlier responses. The
> response is only the most recent author. This is not a history
> course. Just leave the >>'s as they are. No one wants to know who
> said the earlier things, and if they do, the history is there in the
> newsgroup.
>
>>>>>>>>>>>>>>> pianofigh...@gmail.com wrote:
>
>>>>>>>>>>>>>>>> I noticed two very small cracks at the junction
>>>>>>>>>>>>>>>> between the spider arms and the crank, no more than a
>>>>>>>>>>>>>>>> 1/16" to 1/8" in length. Jobst says:
>
> # The trailing spider leg adjacent to the crank generally has a thin
> # web that connects it to the more rigid shaft of the crank, while the
> # three preceding legs are more flexible, stress is concentrated at
> # this web. These cracks are relatively benign because they are easily
> # seen and rarely progress to failure."
>
>>>> When anodizing cracks DO contribute to a reduced fatigue life of
>>>> aluminum, how do they do so? Or is it now your position that
>>>> anodizing CAN reduce the fatigue life of aluminum, but never does
>>>> so in actual fact?
>
>>> simply, it does when it does, it doesn't when it doesn't. you look
>>> at the failure - that's analysis.
>
>> You assert that it can happen, but you have no idea by what
>> mechanism it happens? In other words, you have no idea what you're
>> talking about. Except of course, "it does when it does, it doesn't
>> when it doesn't."
>
>>> just because something's anodized doesn't mean it fails. cranks,
>>> handlebars, brakes, seat posts, stems - all are anodized, but none
>>> are subject to "tension as high as the [insert component name here]
>>> can bear". reality is, anodizing /prevents/ failure because it
>>> prevents corrosion which cause surface defects which can initiate
>>> fatigue.
>
>> And cracks in the anodizing expose the underlying aluminum to
>> corrosion -- a google search will show you references to that as
>> well.
>
> That is not the principal cause of failure. Recall having skinned
> your knee and developing a scab on the wound. If you flex the knee in
> a way that stresses the scab, which in effect is a hard coating on the
> skin and flesh, it will crack and bleed. That the substructure is
> broken by the hard skin is apparent from bleeding. Unfortunately
> aluminum doesn't bleed, but it reacts the same, anodizing being many
> times harder and more brittle than aluminum.
but the cutesy familiar little analogy doesn't alter the fact that the
OBSERVED FAILURE MECHANISM IS NOT THAT OF CRACKING CAUSED BY CRACKS IN
THE ANODIZING!!!
go back to your dye penetrant testing jobst. doubtless it'll tell you
how much is "spoke tension as high as the rim can bear".
|
| | | | |
Date: 14 May 2007 08:51:22
From: Tim McNamara
Subject: Re: mild cracks in right crank
|
In article <6NmdnQuMcPkXQtrbnZ2dnUVZ_qrinZ2d@speakeasy.net >,
jim beam <spamvortex@bad.example.net > wrote:
> jobst.brandt@stanfordalumni.org wrote:
> > That is not the principal cause of failure. Recall having skinned
> > your knee and developing a scab on the wound. If you flex the knee
> > in a way that stresses the scab, which in effect is a hard coating
> > on the skin and flesh, it will crack and bleed. That the
> > substructure is broken by the hard skin is apparent from bleeding.
> > Unfortunately aluminum doesn't bleed, but it reacts the same,
> > anodizing being many times harder and more brittle than aluminum.
>
> but the cutesy familiar little analogy doesn't alter the fact that
> the OBSERVED FAILURE MECHANISM IS NOT THAT OF CRACKING CAUSED BY
> CRACKS IN THE ANODIZING!!!
Which you have yet to prove, a difficult task given that the available
information contradicts you- both from the perspective of real
metallurgists and from practical experience. But when confronted with
facts, you just resort to shouting and name-calling. Do you stamp your
feet, too?
|
| | |
Date: 13 May 2007 20:42:02
From: jim beam
Subject: Re: mild cracks in right crank
|
Gary Young wrote:
> On Sun, 13 May 2007 17:32:22 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>>>>
>>>>>> Gary Young wrote:
>>>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>>>>
>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>>>>>>>> says,
>>>>>>>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>>>>>>>> NR.
>>>>>>>>>>>>>>> Thanks
>>>>>>>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>>>>>>>> enjoy your flight.
>>>>>>>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>>>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>>>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>>>>>>>> where. definitely not in a root.
>>>>>>>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>>>>>>>> panel.
>>>>>>>>>>>> you forget - there's different safety criteria for the military. and
>>>>>>>>>>>> the equipment is operated on the bleeding edge.
>>>>>>>>>>> The safety criteria for the military is more strict than the civilian
>>>>>>>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>>>>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>>>>>>>> all.
>>>>>>>>>>>>> Small
>>>>>>>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>>>>>>>> from the news, seldom result in wings coming off.
>>>>>>>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>>>>>>>> aviation wrenches do on aircraft.
>>>>>>>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>>>>>>>> they progress into this kind of failure - not something to ignore.
>>>>>>>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>>>>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>>>>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>>>>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>>>>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>>>>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>>>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>>>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>>>>>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>>>>>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>>>>>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>>>>>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>>>>>>>> 100,000 hours, it's not.
>>>>>>>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>>>>>>>> common place, it is not. Milspec aircraft maintenance is much more
>>>>>>>>> rigorous than civilian. Military aircraft, with service lives measured
>>>>>>>>> in decades, also have logbooks with aircraft hours measured in the
>>>>>>>>> many thousands. In modern combat, just 'keeping them flying' at any
>>>>>>>>> cost are the things of John Wayne movies, not reality. A poorly
>>>>>>>>> maintained A/C in combat is much more likely to get the aircrew killed
>>>>>>>>> and not kill the bad guy than a well maintained one. Done with this
>>>>>>>>> thread..you are too eager to argue, this thread along with the hard
>>>>>>>>> anodized thread. I imagine you sitting at your keyboard
>>>>>>>>> shouting...adios.
>>>>>>>> with the greatest of respect, i used to - oh, what's the point.
>>>>>>>>
>>>>>>>>>> returning to the crank, filing the surface to make the cracks invisible
>>>>>>>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>>>>>>>> the solution is replacement, pure and simple. you see these cranks at
>>>>>>>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>>>>>>>> and ride, go ahead. i think recommending their continued use to others
>>>>>>>>>> is reckless and irresponsible.
>>>>>>>> i still stand by that - cracked equipment is going to fail. there is no
>>>>>>>> "if", simply "when".
>>>>>>> And thus cracked anodizing leads to rim failure. If not, why not?
>>>>>> er, because cracked anodizing is not cracked aluminum...
>>>>> er, in the "Mavic Open Pro" thread, you've conceded that anodizing reduces
>>>>> the fatigue life of aluminum.
>>>> you're putting words into my mouth - i said it /can/, not that it
>>>> /does/. there is a distinction. just like bearings /can/ false
>>>> brinell. it doesn't mean that they /do/.
>>>>
>>>>> How does that happen if not by anodizing
>>>>> cracks propagating into the underlying aluminum?
>>>> because cracked anodizing is not cracked aluminum. assuming that
>>>> because something /can/ means something /does/ is the fundamental
>>>> mistake jobst makes repeatedly.
>>> When anodizing cracks DO contribute to a reduced fatigue life of aluminum,
>>> how do they do so? Or is it now your position that anodizing CAN reduce
>>> the fatigue life of aluminum, but never does so in actual fact?
>> simply, it does when it does, it doesn't when it doesn't. you look at
>> the failure - that's analysis.
>>
>
> You assert that it can happen, but you have no idea by what mechanism it
> happens?
no gary, i'm saying you can't presume any damned thing unless you bother
to do the analysis, with the correct tools and know that you're looking
at! otherwise "opinion" may as well come from the psychic hotline for
all the value it has.
> In other words, you have no idea what you're talking about.
> Except of course, "it does when it does, it doesn't when it doesn't."
no, it's a statement of reality! sheesh. does your dentist know why
your tooth is aching unless they inspect, analyze and know what they're
doing?
>
>> just because something's anodized doesn't mean it fails. cranks,
>> handlebars, brakes, seat posts, stems - all are anodized, but none are
>> subject to "tension as high as the [insert component name here] can
>> bear". reality is, anodizing /prevents/ failure because it prevents
>> corrosion which cause surface defects which can initiate fatigue.
>
> And cracks in the anodizing expose the underlying aluminum to corrosion --
> a google search will show you references to that as well.
it can, but the extent of exposure is limited. accepting underinformed
presumption that anodizing is "cause" is somewhat naive.
|
| | | |
Date: 14 May 2007 08:57:59
From: Tim McNamara
Subject: Re: mild cracks in right crank
|
In article <pcSdnRX8mcEWR9rbnZ2dnUVZ_h2pnZ2d@speakeasy.net >,
jim beam <spamvortex@bad.example.net > wrote:
> Gary Young wrote:
<snip many layers of attribution >
> > jim beam <spamvortex@bad.example.net> wrote:
> >> simply, it does when it does, it doesn't when it doesn't. you
> >> look at the failure - that's analysis.
> >
> > You assert that it can happen, but you have no idea by what
> > mechanism it happens?
>
> no gary, i'm saying you can't presume any damned thing unless you
> bother to do the analysis, with the correct tools and know that
> you're looking at! otherwise "opinion" may as well come from the
> psychic hotline for all the value it has.
So it is not possible to apply previous knowledge to current similar
cases? Understanding has to begin from a blank slate each time? Human
progress would be difficult in your world, which explains a lot about
your posts.
Of course, your position that "i'm saying you can't presume any damned
thing unless you bother to do the analysis, with the correct tools and
know that you're looking at" invalidates your own posts, since you
haven't provided any evidence that you've done those things either. You
just issue challenges for other people to do the work to prove your
contentions.
|
| |
Date: 13 May 2007 18:37:18
From: Gary Young
Subject: Re: mild cracks in right crank
|
On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
> Gary Young wrote:
>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>
>>> Gary Young wrote:
>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>
>>>>> Qui si parla Campagnolo wrote:
>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>>>>> says,
>>>>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>>>>> NR.
>>>>>>>>>>>> Thanks
>>>>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>>>>> enjoy your flight.
>>>>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>>>>> where. definitely not in a root.
>>>>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>>>>> panel.
>>>>>>>>> you forget - there's different safety criteria for the military. and
>>>>>>>>> the equipment is operated on the bleeding edge.
>>>>>>>> The safety criteria for the military is more strict than the civilian
>>>>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>>>>> all.
>>>>>>>>>> Small
>>>>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>>>>> from the news, seldom result in wings coming off.
>>>>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>>>>> aviation wrenches do on aircraft.
>>>>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>>>>> they progress into this kind of failure - not something to ignore.
>>>>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>>>>> 100,000 hours, it's not.
>>>>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>>>>> common place, it is not. Milspec aircraft maintenance is much more
>>>>>> rigorous than civilian. Military aircraft, with service lives measured
>>>>>> in decades, also have logbooks with aircraft hours measured in the
>>>>>> many thousands. In modern combat, just 'keeping them flying' at any
>>>>>> cost are the things of John Wayne movies, not reality. A poorly
>>>>>> maintained A/C in combat is much more likely to get the aircrew killed
>>>>>> and not kill the bad guy than a well maintained one. Done with this
>>>>>> thread..you are too eager to argue, this thread along with the hard
>>>>>> anodized thread. I imagine you sitting at your keyboard
>>>>>> shouting...adios.
>>>>> with the greatest of respect, i used to - oh, what's the point.
>>>>>
>>>>>>> returning to the crank, filing the surface to make the cracks invisible
>>>>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>>>>> the solution is replacement, pure and simple. you see these cranks at
>>>>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>>>>> and ride, go ahead. i think recommending their continued use to others
>>>>>>> is reckless and irresponsible.
>>>>> i still stand by that - cracked equipment is going to fail. there is no
>>>>> "if", simply "when".
>>>> And thus cracked anodizing leads to rim failure. If not, why not?
>>> er, because cracked anodizing is not cracked aluminum...
>>
>> er, in the "Mavic Open Pro" thread, you've conceded that anodizing reduces
>> the fatigue life of aluminum.
>
> you're putting words into my mouth - i said it /can/, not that it
> /does/. there is a distinction. just like bearings /can/ false
> brinell. it doesn't mean that they /do/.
>
>> How does that happen if not by anodizing
>> cracks propagating into the underlying aluminum?
>
> because cracked anodizing is not cracked aluminum. assuming that
> because something /can/ means something /does/ is the fundamental
> mistake jobst makes repeatedly.
When anodizing cracks DO contribute to a reduced fatigue life of aluminum,
how do they do so? Or is it now your position that anodizing CAN reduce
the fatigue life of aluminum, but never does so in actual fact?
|
| | |
Date: 13 May 2007 17:32:22
From: jim beam
Subject: Re: mild cracks in right crank
|
Gary Young wrote:
> On Sun, 13 May 2007 16:13:54 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>>>
>>>>>> Qui si parla Campagnolo wrote:
>>>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>>>>>> says,
>>>>>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>>>>>> NR.
>>>>>>>>>>>>> Thanks
>>>>>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>>>>>> enjoy your flight.
>>>>>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>>>>>> where. definitely not in a root.
>>>>>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>>>>>> panel.
>>>>>>>>>> you forget - there's different safety criteria for the military. and
>>>>>>>>>> the equipment is operated on the bleeding edge.
>>>>>>>>> The safety criteria for the military is more strict than the civilian
>>>>>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>>>>>> all.
>>>>>>>>>>> Small
>>>>>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>>>>>> from the news, seldom result in wings coming off.
>>>>>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>>>>>> aviation wrenches do on aircraft.
>>>>>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>>>>>> they progress into this kind of failure - not something to ignore.
>>>>>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>>>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>>>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>>>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>>>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>>>>>> 100,000 hours, it's not.
>>>>>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>>>>>> common place, it is not. Milspec aircraft maintenance is much more
>>>>>>> rigorous than civilian. Military aircraft, with service lives measured
>>>>>>> in decades, also have logbooks with aircraft hours measured in the
>>>>>>> many thousands. In modern combat, just 'keeping them flying' at any
>>>>>>> cost are the things of John Wayne movies, not reality. A poorly
>>>>>>> maintained A/C in combat is much more likely to get the aircrew killed
>>>>>>> and not kill the bad guy than a well maintained one. Done with this
>>>>>>> thread..you are too eager to argue, this thread along with the hard
>>>>>>> anodized thread. I imagine you sitting at your keyboard
>>>>>>> shouting...adios.
>>>>>> with the greatest of respect, i used to - oh, what's the point.
>>>>>>
>>>>>>>> returning to the crank, filing the surface to make the cracks invisible
>>>>>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>>>>>> the solution is replacement, pure and simple. you see these cranks at
>>>>>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>>>>>> and ride, go ahead. i think recommending their continued use to others
>>>>>>>> is reckless and irresponsible.
>>>>>> i still stand by that - cracked equipment is going to fail. there is no
>>>>>> "if", simply "when".
>>>>> And thus cracked anodizing leads to rim failure. If not, why not?
>>>> er, because cracked anodizing is not cracked aluminum...
>>> er, in the "Mavic Open Pro" thread, you've conceded that anodizing reduces
>>> the fatigue life of aluminum.
>> you're putting words into my mouth - i said it /can/, not that it
>> /does/. there is a distinction. just like bearings /can/ false
>> brinell. it doesn't mean that they /do/.
>>
>>> How does that happen if not by anodizing
>>> cracks propagating into the underlying aluminum?
>> because cracked anodizing is not cracked aluminum. assuming that
>> because something /can/ means something /does/ is the fundamental
>> mistake jobst makes repeatedly.
>
> When anodizing cracks DO contribute to a reduced fatigue life of aluminum,
> how do they do so? Or is it now your position that anodizing CAN reduce
> the fatigue life of aluminum, but never does so in actual fact?
simply, it does when it does, it doesn't when it doesn't. you look at
the failure - that's analysis.
just because something's anodized doesn't mean it fails. cranks,
handlebars, brakes, seat posts, stems - all are anodized, but none are
subject to "tension as high as the [insert component name here] can
bear". reality is, anodizing /prevents/ failure because it prevents
corrosion which cause surface defects which can initiate fatigue.
|
| |
Date: 13 May 2007 17:57:27
From: Gary Young
Subject: Re: mild cracks in right crank
|
On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
> Gary Young wrote:
>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>
>>> Qui si parla Campagnolo wrote:
>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>> Qui si parla Campagnolo wrote:
>>>>>
>>>>>
>>>>>
>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>>> says,
>>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>>> NR.
>>>>>>>>>> Thanks
>>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>>> enjoy your flight.
>>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>>> where. definitely not in a root.
>>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>>> panel.
>>>>>>> you forget - there's different safety criteria for the military. and
>>>>>>> the equipment is operated on the bleeding edge.
>>>>>> The safety criteria for the military is more strict than the civilian
>>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>>> all.
>>>>>>>> Small
>>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>>> from the news, seldom result in wings coming off.
>>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>>> aviation wrenches do on aircraft.
>>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>>> they progress into this kind of failure - not something to ignore.
>>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>>> 100,000 hours, it's not.
>>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>>> common place, it is not. Milspec aircraft maintenance is much more
>>>> rigorous than civilian. Military aircraft, with service lives measured
>>>> in decades, also have logbooks with aircraft hours measured in the
>>>> many thousands. In modern combat, just 'keeping them flying' at any
>>>> cost are the things of John Wayne movies, not reality. A poorly
>>>> maintained A/C in combat is much more likely to get the aircrew killed
>>>> and not kill the bad guy than a well maintained one. Done with this
>>>> thread..you are too eager to argue, this thread along with the hard
>>>> anodized thread. I imagine you sitting at your keyboard
>>>> shouting...adios.
>>> with the greatest of respect, i used to - oh, what's the point.
>>>
>>>>> returning to the crank, filing the surface to make the cracks invisible
>>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>>> the solution is replacement, pure and simple. you see these cranks at
>>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>>> and ride, go ahead. i think recommending their continued use to others
>>>>> is reckless and irresponsible.
>>> i still stand by that - cracked equipment is going to fail. there is no
>>> "if", simply "when".
>>
>> And thus cracked anodizing leads to rim failure. If not, why not?
>
> er, because cracked anodizing is not cracked aluminum...
er, in the "Mavic Open Pro" thread, you've conceded that anodizing reduces
the fatigue life of aluminum. How does that happen if not by anodizing
cracks propagating into the underlying aluminum?
|
| | |
Date: 13 May 2007 16:13:54
From: jim beam
Subject: Re: mild cracks in right crank
|
Gary Young wrote:
> On Sun, 13 May 2007 15:39:34 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>>>
>>>> Qui si parla Campagnolo wrote:
>>>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>> Qui si parla Campagnolo wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>> Qui si parla Campagnolo wrote:
>>>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>>>> says,
>>>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>>>> NR.
>>>>>>>>>>> Thanks
>>>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>>>> enjoy your flight.
>>>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>>>> where. definitely not in a root.
>>>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>>>> panel.
>>>>>>>> you forget - there's different safety criteria for the military. and
>>>>>>>> the equipment is operated on the bleeding edge.
>>>>>>> The safety criteria for the military is more strict than the civilian
>>>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>>>> all.
>>>>>>>>> Small
>>>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>>>> from the news, seldom result in wings coming off.
>>>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>>>> aviation wrenches do on aircraft.
>>>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>>>> they progress into this kind of failure - not something to ignore.
>>>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>>>> 100,000 hours, it's not.
>>>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>>>> common place, it is not. Milspec aircraft maintenance is much more
>>>>> rigorous than civilian. Military aircraft, with service lives measured
>>>>> in decades, also have logbooks with aircraft hours measured in the
>>>>> many thousands. In modern combat, just 'keeping them flying' at any
>>>>> cost are the things of John Wayne movies, not reality. A poorly
>>>>> maintained A/C in combat is much more likely to get the aircrew killed
>>>>> and not kill the bad guy than a well maintained one. Done with this
>>>>> thread..you are too eager to argue, this thread along with the hard
>>>>> anodized thread. I imagine you sitting at your keyboard
>>>>> shouting...adios.
>>>> with the greatest of respect, i used to - oh, what's the point.
>>>>
>>>>>> returning to the crank, filing the surface to make the cracks invisible
>>>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>>>> the solution is replacement, pure and simple. you see these cranks at
>>>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>>>> and ride, go ahead. i think recommending their continued use to others
>>>>>> is reckless and irresponsible.
>>>> i still stand by that - cracked equipment is going to fail. there is no
>>>> "if", simply "when".
>>> And thus cracked anodizing leads to rim failure. If not, why not?
>> er, because cracked anodizing is not cracked aluminum...
>
> er, in the "Mavic Open Pro" thread, you've conceded that anodizing reduces
> the fatigue life of aluminum.
you're putting words into my mouth - i said it /can/, not that it
/does/. there is a distinction. just like bearings /can/ false
brinell. it doesn't mean that they /do/.
> How does that happen if not by anodizing
> cracks propagating into the underlying aluminum?
because cracked anodizing is not cracked aluminum. assuming that
because something /can/ means something /does/ is the fundamental
mistake jobst makes repeatedly.
|
| | | |
Date: 14 May 2007 03:02:09
From:
Subject: Re: mild cracks in right crank
|
Dewar's White Label writes:
>>>>> i still stand by that - cracked equipment is going to fail.
>>>>> there is no "if", simply "when".
>>>> And thus cracked anodizing leads to rim failure. If not, why not?
>>> er, because cracked anodizing is not cracked aluminum...
>> er, in the "Mavic Open Pro" thread, you've conceded that anodizing
>> reduces the fatigue life of aluminum.
> you're putting words into my mouth - i said it /can/, not that it
> /does/. there is a distinction. just like bearings /can/ false
> brinell. it doesn't mean that they /do/.
>> How does that happen if not by anodizing cracks propagating into
>> the underlying aluminum?
> because cracked anodizing is not cracked aluminum. assuming that
> because something /can/ means something /does/ is the fundamental
> mistake jobst makes repeatedly.
Oops! I see we are on the slippery slope and gaining speed. Next
thing may be that spoke tension "may" have an effect on wheel
strength. Wonders never cease!
Jobst Brandt
|
| | | | |
Date: 13 May 2007 20:35:08
From: jim beam
Subject: Re: mild cracks in right crank
|
jobst.brandt@stanfordalumni.org wrote:
> Dewar's White Label writes:
>
>>>>>> i still stand by that - cracked equipment is going to fail.
>>>>>> there is no "if", simply "when".
>
>>>>> And thus cracked anodizing leads to rim failure. If not, why not?
>
>>>> er, because cracked anodizing is not cracked aluminum...
>
>>> er, in the "Mavic Open Pro" thread, you've conceded that anodizing
>>> reduces the fatigue life of aluminum.
>
>> you're putting words into my mouth - i said it /can/, not that it
>> /does/. there is a distinction. just like bearings /can/ false
>> brinell. it doesn't mean that they /do/.
>
>>> How does that happen if not by anodizing cracks propagating into
>>> the underlying aluminum?
>
>> because cracked anodizing is not cracked aluminum. assuming that
>> because something /can/ means something /does/ is the fundamental
>> mistake jobst makes repeatedly.
>
> Oops! I see we are on the slippery slope and gaining speed. Next
> thing may be that spoke tension "may" have an effect on wheel
> strength. Wonders never cease!
from a guy that thinks a dye penetrant test somehow differentiates
cracking initiators, that's not a very smart comment.
|
| |
Date: 13 May 2007 14:38:04
From: Gary Young
Subject: Re: mild cracks in right crank
|
On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
> Qui si parla Campagnolo wrote:
>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>> Qui si parla Campagnolo wrote:
>>>
>>>
>>>
>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>> Qui si parla Campagnolo wrote:
>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>> says,
>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>> seen and rarely progress to failure."
>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>> NR.
>>>>>>>> Thanks
>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>> enjoy your flight.
>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>> where. definitely not in a root.
>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>> panel.
>>>>> you forget - there's different safety criteria for the military. and
>>>>> the equipment is operated on the bleeding edge.
>>>> The safety criteria for the military is more strict than the civilian
>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>> all.
>>>>>> Small
>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>> from the news, seldom result in wings coming off.
>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>> aviation wrenches do on aircraft.
>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>> they progress into this kind of failure - not something to ignore.
>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>> miles. To imply that failure is imminent is not true, any more than a
>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>> ok, there's repaired as in to proper spec and there's repaired to a
>>> standard considered battleworthy. stop drilling is the latter. for an
>>> air frame with maybe 1,000 hours life expectancy, that might be
>>> acceptable. for a 747 with an airframe life expectancy measured above
>>> 100,000 hours, it's not.
>>
>> Well, Jim, you imply that quick stop repair of military aircraft is
>> common place, it is not. Milspec aircraft maintenance is much more
>> rigorous than civilian. Military aircraft, with service lives measured
>> in decades, also have logbooks with aircraft hours measured in the
>> many thousands. In modern combat, just 'keeping them flying' at any
>> cost are the things of John Wayne movies, not reality. A poorly
>> maintained A/C in combat is much more likely to get the aircrew killed
>> and not kill the bad guy than a well maintained one. Done with this
>> thread..you are too eager to argue, this thread along with the hard
>> anodized thread. I imagine you sitting at your keyboard
>> shouting...adios.
>
> with the greatest of respect, i used to - oh, what's the point.
>
>>> returning to the crank, filing the surface to make the cracks invisible
>>> isn't going to make them actually disappear. or prevent reappearance.
>>> the solution is replacement, pure and simple. you see these cranks at
>>> swap meets, with cracks, all the time. if you personally want to buy
>>> and ride, go ahead. i think recommending their continued use to others
>>> is reckless and irresponsible.
>
> i still stand by that - cracked equipment is going to fail. there is no
> "if", simply "when".
And thus cracked anodizing leads to rim failure. If not, why not?
|
| | |
Date: 13 May 2007 15:39:34
From: jim beam
Subject: Re: mild cracks in right crank
|
Gary Young wrote:
> On Sun, 13 May 2007 09:40:58 -0700, jim beam wrote:
>
>> Qui si parla Campagnolo wrote:
>>> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>> Qui si parla Campagnolo wrote:
>>>>
>>>>
>>>>
>>>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>>> Qui si parla Campagnolo wrote:
>>>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>> pianofigh...@gmail.com wrote:
>>>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>>>> says,
>>>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>>>> seen and rarely progress to failure."
>>>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>>>> NR.
>>>>>>>>> Thanks
>>>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>>>> enjoy your flight.
>>>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>>>> be found in everything from wing spars to the aluminum skin.
>>>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>>>> where. definitely not in a root.
>>>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>>>> panel.
>>>>>> you forget - there's different safety criteria for the military. and
>>>>>> the equipment is operated on the bleeding edge.
>>>>> The safety criteria for the military is more strict than the civilian
>>>>> world, not less. The rigors the A/C are subjected to demands this.
>>>>> Cracks that would make the mere civilian cringe are not uncommon at
>>>>> all.
>>>>>>> Small
>>>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>>>> from the news, seldom result in wings coming off.
>>>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>>>> aviation wrenches do on aircraft.
>>>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>>>> they progress into this kind of failure - not something to ignore.
>>>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>>>> failure. Many more have had these 'stopped', and ridden for many more
>>>>> miles. To imply that failure is imminent is not true, any more than a
>>>>> crack in a ruder or wing spar means that piece is going to break off.
>>>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>>>> ok, there's repaired as in to proper spec and there's repaired to a
>>>> standard considered battleworthy. stop drilling is the latter. for an
>>>> air frame with maybe 1,000 hours life expectancy, that might be
>>>> acceptable. for a 747 with an airframe life expectancy measured above
>>>> 100,000 hours, it's not.
>>> Well, Jim, you imply that quick stop repair of military aircraft is
>>> common place, it is not. Milspec aircraft maintenance is much more
>>> rigorous than civilian. Military aircraft, with service lives measured
>>> in decades, also have logbooks with aircraft hours measured in the
>>> many thousands. In modern combat, just 'keeping them flying' at any
>>> cost are the things of John Wayne movies, not reality. A poorly
>>> maintained A/C in combat is much more likely to get the aircrew killed
>>> and not kill the bad guy than a well maintained one. Done with this
>>> thread..you are too eager to argue, this thread along with the hard
>>> anodized thread. I imagine you sitting at your keyboard
>>> shouting...adios.
>> with the greatest of respect, i used to - oh, what's the point.
>>
>>>> returning to the crank, filing the surface to make the cracks invisible
>>>> isn't going to make them actually disappear. or prevent reappearance.
>>>> the solution is replacement, pure and simple. you see these cranks at
>>>> swap meets, with cracks, all the time. if you personally want to buy
>>>> and ride, go ahead. i think recommending their continued use to others
>>>> is reckless and irresponsible.
>> i still stand by that - cracked equipment is going to fail. there is no
>> "if", simply "when".
>
> And thus cracked anodizing leads to rim failure. If not, why not?
er, because cracked anodizing is not cracked aluminum...
|
| |
Date: 13 May 2007 05:48:36
From: Qui si parla Campagnolo
Subject: Re: mild cracks in right crank
|
On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net > wrote:
> Qui si parla Campagnolo wrote:
>
>
>
> > On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
> >> Qui si parla Campagnolo wrote:
>
> >>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
> >>>> pianofigh...@gmail.com wrote:
> >>>>> I noticed two very small cracks at the junction between the spider
> >>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
> >>>>> says,
> >>>>> "The trailing spider leg adjacent to the crank generally has a
> >>>>> thin web that connects it to the more rigid shaft of the crank, while
> >>>>> the three preceding legs are more flexible, stress is concentrated at
> >>>>> this web. These cracks are relatively benign because they are easily
> >>>>> seen and rarely progress to failure."
> >>>>> Should I file and then sand the cracks out before they get worse, or
> >>>>> leave them? Does anyone have any experience with this? The cranks are
> >>>>> NR.
> >>>>> Thanks
> >>>> thank you for flying self-deception airways, this is your captain
> >>>> speaking. please ignore the "mild cracks" that are progressing though
> >>>> our wing roots at this time. when the wings have detached, the cabin
> >>>> crew will hand out hard candy to suck to assist with cabin
> >>>> pressurization differences as we re-adjust our altitude. we hope you
> >>>> enjoy your flight.
> >>> Well Jim, in military aircraft, small cracks are very common, and can
> >>> be found in everything from wing spars to the aluminum skin.
> >> but with respect, it's a matter of where. if it's just a skin panel in
> >> a non-critical location [not a leading edge], fine. spars, it depends
> >> where. definitely not in a root.
>
> > base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
> > panel.
> >> you forget - there's different safety criteria for the military. and
> >> the equipment is operated on the bleeding edge.
>
> > The safety criteria for the military is more strict than the civilian
> > world, not less. The rigors the A/C are subjected to demands this.
> > Cracks that would make the mere civilian cringe are not uncommon at
> > all.
> >>> Small
> >>> cracks in civilian aircraft are not uncommon either and as you can see
> >>> from the news, seldom result in wings coming off.
> >>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
> >>> aviation wrenches do on aircraft.
> >> i strongly disagree. those "mild cracks" are located precisely where
> >> they progress into this kind of failure - not something to ignore.
>
> > Many of these cranks have been ridden for miles, with cracks, w/o
> > failure. Many more have had these 'stopped', and ridden for many more
> > miles. To imply that failure is imminent is not true, any more than a
> > crack in a ruder or wing spar means that piece is going to break off.
> > The OP is not ignoring them, he is asking if removing the cracks, much
> > like A/C cracks are stop drilled, is appropriate and it is.
> >>http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
> >> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>
> ok, there's repaired as in to proper spec and there's repaired to a
> standard considered battleworthy. stop drilling is the latter. for an
> air frame with maybe 1,000 hours life expectancy, that might be
> acceptable. for a 747 with an airframe life expectancy measured above
> 100,000 hours, it's not.
Well, Jim, you imply that quick stop repair of military aircraft is
common place, it is not. Milspec aircraft maintenance is much more
rigorous than civilian. Military aircraft, with service lives measured
in decades, also have logbooks with aircraft hours measured in the
many thousands. In modern combat, just 'keeping them flying' at any
cost are the things of John Wayne movies, not reality. A poorly
maintained A/C in combat is much more likely to get the aircrew killed
and not kill the bad guy than a well maintained one. Done with this
thread..you are too eager to argue, this thread along with the hard
anodized thread. I imagine you sitting at your keyboard
shouting...adios.
>
> returning to the crank, filing the surface to make the cracks invisible
> isn't going to make them actually disappear. or prevent reappearance.
> the solution is replacement, pure and simple. you see these cranks at
> swap meets, with cracks, all the time. if you personally want to buy
> and ride, go ahead. i think recommending their continued use to others
> is reckless and irresponsible.
|
| | |
Date: 13 May 2007 09:40:58
From: jim beam
Subject: Re: mild cracks in right crank
|
Qui si parla Campagnolo wrote:
> On May 12, 12:13 pm, jim beam <spamvor...@bad.example.net> wrote:
>> Qui si parla Campagnolo wrote:
>>
>>
>>
>>> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>>>> Qui si parla Campagnolo wrote:
>>>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>> pianofigh...@gmail.com wrote:
>>>>>>> I noticed two very small cracks at the junction between the spider
>>>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>>>> says,
>>>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>>>> this web. These cracks are relatively benign because they are easily
>>>>>>> seen and rarely progress to failure."
>>>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>>>> NR.
>>>>>>> Thanks
>>>>>> thank you for flying self-deception airways, this is your captain
>>>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>>>> our wing roots at this time. when the wings have detached, the cabin
>>>>>> crew will hand out hard candy to suck to assist with cabin
>>>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>>>> enjoy your flight.
>>>>> Well Jim, in military aircraft, small cracks are very common, and can
>>>>> be found in everything from wing spars to the aluminum skin.
>>>> but with respect, it's a matter of where. if it's just a skin panel in
>>>> a non-critical location [not a leading edge], fine. spars, it depends
>>>> where. definitely not in a root.
>>> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
>>> panel.
>>>> you forget - there's different safety criteria for the military. and
>>>> the equipment is operated on the bleeding edge.
>>> The safety criteria for the military is more strict than the civilian
>>> world, not less. The rigors the A/C are subjected to demands this.
>>> Cracks that would make the mere civilian cringe are not uncommon at
>>> all.
>>>>> Small
>>>>> cracks in civilian aircraft are not uncommon either and as you can see
>>>>> from the news, seldom result in wings coming off.
>>>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>>>> aviation wrenches do on aircraft.
>>>> i strongly disagree. those "mild cracks" are located precisely where
>>>> they progress into this kind of failure - not something to ignore.
>>> Many of these cranks have been ridden for miles, with cracks, w/o
>>> failure. Many more have had these 'stopped', and ridden for many more
>>> miles. To imply that failure is imminent is not true, any more than a
>>> crack in a ruder or wing spar means that piece is going to break off.
>>> The OP is not ignoring them, he is asking if removing the cracks, much
>>> like A/C cracks are stop drilled, is appropriate and it is.
>>>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>>>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>> ok, there's repaired as in to proper spec and there's repaired to a
>> standard considered battleworthy. stop drilling is the latter. for an
>> air frame with maybe 1,000 hours life expectancy, that might be
>> acceptable. for a 747 with an airframe life expectancy measured above
>> 100,000 hours, it's not.
>
> Well, Jim, you imply that quick stop repair of military aircraft is
> common place, it is not. Milspec aircraft maintenance is much more
> rigorous than civilian. Military aircraft, with service lives measured
> in decades, also have logbooks with aircraft hours measured in the
> many thousands. In modern combat, just 'keeping them flying' at any
> cost are the things of John Wayne movies, not reality. A poorly
> maintained A/C in combat is much more likely to get the aircrew killed
> and not kill the bad guy than a well maintained one. Done with this
> thread..you are too eager to argue, this thread along with the hard
> anodized thread. I imagine you sitting at your keyboard
> shouting...adios.
with the greatest of respect, i used to - oh, what's the point.
>> returning to the crank, filing the surface to make the cracks invisible
>> isn't going to make them actually disappear. or prevent reappearance.
>> the solution is replacement, pure and simple. you see these cranks at
>> swap meets, with cracks, all the time. if you personally want to buy
>> and ride, go ahead. i think recommending their continued use to others
>> is reckless and irresponsible.
i still stand by that - cracked equipment is going to fail. there is no
"if", simply "when".
|
| |
Date: 12 May 2007 08:43:56
From: Qui si parla Campagnolo
Subject: Re: mild cracks in right crank
|
On May 12, 6:46 am, jim beam <spamvor...@bad.example.net > wrote:
> Qui si parla Campagnolo wrote:
>
>
>
> > On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
> >> pianofigh...@gmail.com wrote:
> >>> I noticed two very small cracks at the junction between the spider
> >>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
> >>> says,
> >>> "The trailing spider leg adjacent to the crank generally has a
> >>> thin web that connects it to the more rigid shaft of the crank, while
> >>> the three preceding legs are more flexible, stress is concentrated at
> >>> this web. These cracks are relatively benign because they are easily
> >>> seen and rarely progress to failure."
> >>> Should I file and then sand the cracks out before they get worse, or
> >>> leave them? Does anyone have any experience with this? The cranks are
> >>> NR.
> >>> Thanks
> >> thank you for flying self-deception airways, this is your captain
> >> speaking. please ignore the "mild cracks" that are progressing though
> >> our wing roots at this time. when the wings have detached, the cabin
> >> crew will hand out hard candy to suck to assist with cabin
> >> pressurization differences as we re-adjust our altitude. we hope you
> >> enjoy your flight.
>
> > Well Jim, in military aircraft, small cracks are very common, and can
> > be found in everything from wing spars to the aluminum skin.
>
> but with respect, it's a matter of where. if it's just a skin panel in
> a non-critical location [not a leading edge], fine. spars, it depends
> where. definitely not in a root.
base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
panel.
>
> you forget - there's different safety criteria for the military. and
> the equipment is operated on the bleeding edge.
The safety criteria for the military is more strict than the civilian
world, not less. The rigors the A/C are subjected to demands this.
Cracks that would make the mere civilian cringe are not uncommon at
all.
>
> > Small
> > cracks in civilian aircraft are not uncommon either and as you can see
> > from the news, seldom result in wings coming off.
>
> > For the OP, yes, sand or otherwise remove/reduce the cracks..just like
> > aviation wrenches do on aircraft.
>
> i strongly disagree. those "mild cracks" are located precisely where
> they progress into this kind of failure - not something to ignore.
Many of these cranks have been ridden for miles, with cracks, w/o
failure. Many more have had these 'stopped', and ridden for many more
miles. To imply that failure is imminent is not true, any more than a
crack in a ruder or wing spar means that piece is going to break off.
The OP is not ignoring them, he is asking if removing the cracks, much
like A/C cracks are stop drilled, is appropriate and it is.
>
> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
|
| | |
Date: 12 May 2007 11:13:48
From: jim beam
Subject: Re: mild cracks in right crank
|
Qui si parla Campagnolo wrote:
> On May 12, 6:46 am, jim beam <spamvor...@bad.example.net> wrote:
>> Qui si parla Campagnolo wrote:
>>
>>
>>
>>> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>> pianofigh...@gmail.com wrote:
>>>>> I noticed two very small cracks at the junction between the spider
>>>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>>>> says,
>>>>> "The trailing spider leg adjacent to the crank generally has a
>>>>> thin web that connects it to the more rigid shaft of the crank, while
>>>>> the three preceding legs are more flexible, stress is concentrated at
>>>>> this web. These cracks are relatively benign because they are easily
>>>>> seen and rarely progress to failure."
>>>>> Should I file and then sand the cracks out before they get worse, or
>>>>> leave them? Does anyone have any experience with this? The cranks are
>>>>> NR.
>>>>> Thanks
>>>> thank you for flying self-deception airways, this is your captain
>>>> speaking. please ignore the "mild cracks" that are progressing though
>>>> our wing roots at this time. when the wings have detached, the cabin
>>>> crew will hand out hard candy to suck to assist with cabin
>>>> pressurization differences as we re-adjust our altitude. we hope you
>>>> enjoy your flight.
>>> Well Jim, in military aircraft, small cracks are very common, and can
>>> be found in everything from wing spars to the aluminum skin.
>> but with respect, it's a matter of where. if it's just a skin panel in
>> a non-critical location [not a leading edge], fine. spars, it depends
>> where. definitely not in a root.
>
> base of attach points for F-14 rudders, wing spar of F-16...NOT a skin
> panel.
>> you forget - there's different safety criteria for the military. and
>> the equipment is operated on the bleeding edge.
>
> The safety criteria for the military is more strict than the civilian
> world, not less. The rigors the A/C are subjected to demands this.
> Cracks that would make the mere civilian cringe are not uncommon at
> all.
>>> Small
>>> cracks in civilian aircraft are not uncommon either and as you can see
>>> from the news, seldom result in wings coming off.
>>> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
>>> aviation wrenches do on aircraft.
>> i strongly disagree. those "mild cracks" are located precisely where
>> they progress into this kind of failure - not something to ignore.
>
> Many of these cranks have been ridden for miles, with cracks, w/o
> failure. Many more have had these 'stopped', and ridden for many more
> miles. To imply that failure is imminent is not true, any more than a
> crack in a ruder or wing spar means that piece is going to break off.
> The OP is not ignoring them, he is asking if removing the cracks, much
> like A/C cracks are stop drilled, is appropriate and it is.
>> http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
>> from:http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
>
>
ok, there's repaired as in to proper spec and there's repaired to a
standard considered battleworthy. stop drilling is the latter. for an
air frame with maybe 1,000 hours life expectancy, that might be
acceptable. for a 747 with an airframe life expectancy measured above
100,000 hours, it's not.
returning to the crank, filing the surface to make the cracks invisible
isn't going to make them actually disappear. or prevent reappearance.
the solution is replacement, pure and simple. you see these cranks at
swap meets, with cracks, all the time. if you personally want to buy
and ride, go ahead. i think recommending their continued use to others
is reckless and irresponsible.
|
| |
Date: 12 May 2007 05:30:51
From: Qui si parla Campagnolo
Subject: Re: mild cracks in right crank
|
On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net > wrote:
> pianofigh...@gmail.com wrote:
> > I noticed two very small cracks at the junction between the spider
> > arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
> > says,
> > "The trailing spider leg adjacent to the crank generally has a
> > thin web that connects it to the more rigid shaft of the crank, while
> > the three preceding legs are more flexible, stress is concentrated at
> > this web. These cracks are relatively benign because they are easily
> > seen and rarely progress to failure."
> > Should I file and then sand the cracks out before they get worse, or
> > leave them? Does anyone have any experience with this? The cranks are
> > NR.
>
> > Thanks
>
> thank you for flying self-deception airways, this is your captain
> speaking. please ignore the "mild cracks" that are progressing though
> our wing roots at this time. when the wings have detached, the cabin
> crew will hand out hard candy to suck to assist with cabin
> pressurization differences as we re-adjust our altitude. we hope you
> enjoy your flight.
Well Jim, in military aircraft, small cracks are very common, and can
be found in everything from wing spars to the aluminum skin. Small
cracks in civilian aircraft are not uncommon either and as you can see
from the news, seldom result in wings coming off.
For the OP, yes, sand or otherwise remove/reduce the cracks..just like
aviation wrenches do on aircraft.
|
| | |
Date: 12 May 2007 06:46:16
From: jim beam
Subject: Re: mild cracks in right crank
|
Qui si parla Campagnolo wrote:
> On May 11, 9:37 pm, jim beam <spamvor...@bad.example.net> wrote:
>> pianofigh...@gmail.com wrote:
>>> I noticed two very small cracks at the junction between the spider
>>> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
>>> says,
>>> "The trailing spider leg adjacent to the crank generally has a
>>> thin web that connects it to the more rigid shaft of the crank, while
>>> the three preceding legs are more flexible, stress is concentrated at
>>> this web. These cracks are relatively benign because they are easily
>>> seen and rarely progress to failure."
>>> Should I file and then sand the cracks out before they get worse, or
>>> leave them? Does anyone have any experience with this? The cranks are
>>> NR.
>>> Thanks
>> thank you for flying self-deception airways, this is your captain
>> speaking. please ignore the "mild cracks" that are progressing though
>> our wing roots at this time. when the wings have detached, the cabin
>> crew will hand out hard candy to suck to assist with cabin
>> pressurization differences as we re-adjust our altitude. we hope you
>> enjoy your flight.
>
> Well Jim, in military aircraft, small cracks are very common, and can
> be found in everything from wing spars to the aluminum skin.
but with respect, it's a matter of where. if it's just a skin panel in
a non-critical location [not a leading edge], fine. spars, it depends
where. definitely not in a root.
you forget - there's different safety criteria for the military. and
the equipment is operated on the bleeding edge.
> Small
> cracks in civilian aircraft are not uncommon either and as you can see
> from the news, seldom result in wings coming off.
>
> For the OP, yes, sand or otherwise remove/reduce the cracks..just like
> aviation wrenches do on aircraft.
>
i strongly disagree. those "mild cracks" are located precisely where
they progress into this kind of failure - not something to ignore.
http://technology.open.ac.uk/materials/mem/images/images_cc/ccf11_2.jpg
from:
http://technology.open.ac.uk/materials/mem/mem_ccf4.htm
|
| |
Date: 11 May 2007 20:37:01
From: jim beam
Subject: Re: mild cracks in right crank
|
pianofighter@gmail.com wrote:
> I noticed two very small cracks at the junction between the spider
> arms and the crank, no more than a 1/16" to 1/8" in length. Jobst
> says,
> "The trailing spider leg adjacent to the crank generally has a
> thin web that connects it to the more rigid shaft of the crank, while
> the three preceding legs are more flexible, stress is concentrated at
> this web. These cracks are relatively benign because they are easily
> seen and rarely progress to failure."
> Should I file and then sand the cracks out before they get worse, or
> leave them? Does anyone have any experience with this? The cranks are
> NR.
>
> Thanks
>
thank you for flying self-deception airways, this is your captain
speaking. please ignore the "mild cracks" that are progressing though
our wing roots at this time. when the wings have detached, the cabin
crew will hand out hard candy to suck to assist with cabin
pressurization differences as we re-adjust our altitude. we hope you
enjoy your flight.
|
|
