Gary Young said: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 <[email hidden]> wrote:
>>> Qui si parla Campagnolo wrote:
>>>
>>>
>>>
>>>> On May 12, 6:46 am, jim beam <[email hidden]> wrote:
>>>>> Qui si parla Campagnolo wrote:
>>>>>> On May 11, 9:37 pm, jim beam <[email hidden]> wrote:
>>>>>>> [email hidden] 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?