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RV-12 accident - August 2017

JRo

Well Known Member
Saturday after a normal gentle touchdown at 5B7 the nosewheel departed the aircraft. After skidding a few feet on the nose strut, the strut folded and the prop struck the surface, resulting in sudden engine stoppage. the separated nose wheel struck the right stabilator, resulting in considerable damage to the stabilator. No injuries. Initial inspection of the recovered wheel shows a clean break in the nose wheel fork at a weld point. No cracks were observed prior to this event, even though fork had been carefully inspected in compliance with SB.
 
How many hours on the aircraft? Rough field operations or mostly paved runways? Any botched landings prior such as nose wheel strike?
 
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No cracks were observed prior to this event, even though fork had been carefully inspected in compliance with SB.

I imagine everyone realizes that it is not possible for a normal/gentle landing to fail the nose fork on an RV-12 unless it already had previous (possibly missed / undetected) damage........
 
I imagine everyone realizes that it is not possible for a normal/gentle landing to fail the nose fork on an RV-12 unless it already had previous (possibly missed / undetected) damage........
That's what I would think... so how do you think people are missing the existing damage/cracks? Is an external inspection enough, or could the cracks be starting on the inner parts of the fork and not be visible from the outside without complete disassembly?

I've inspected mine in detail twice recently, once just after the notification was published and once during the condition inspection. I cleaned it off and inspected closely, but stories like this have me wondering if it's enough. I don't recall ever abusing the nose wheel, but I'm not the only person who's flown it.
 
I am guessing that the crack was at the area where the weld and the base metal join. Often there is what almost appears as a crack there, but is just part of the weld process, when that crack follows the irregular path of the edge of the weld, it is easy to miss unless inspected very closely..
 
Is the fork steel or aluminum? It seems like magnaflux or dye-penetrant inspections might be advisable as part of the annual condition inspection.
 
It is aluminum.

QUOTE=snopercod;1199640]Is the fork steel or aluminum? It seems like magnaflux or dye-penetrant inspections might be advisable as part of the annual condition inspection.[/QUOTE]
 
Best way to take care of the problem is to buy the new heavy duty fork. That's what I did. Years ago I made a bad landing with my Long Ez, broke the lighter duty nose fork that I had not replaced with a new heavy duty one. It flew back and trashed my prop. Live and learn!
 
If I understand this correctly, If the fork is not visible for an inspection as a preflight option and is subject to sometime acquiring a crack or breaking at the weld. Why not replace the fork with the updated version??? The cost of doing so versus the optional outcome seems to be a no brainer?? Just saying
 
I would guess that MOST of the RV12 fleet has a wheel pant on the nosewheel. This looks nice etc, but it keeps the nose fork from being inspected unless you remove the two piece cover.
 
Wow! So many questions that my concern is that we are going to overwhelm Jim with questions. Like, when was the nose wheel purchased, (kit number). Is he the original owner/builder? Was the front wheel balanced. Vibration can be very destructive, even in healthy assemblies. In addition to the earlier posted questions, we need all of the information that we can get to help determine if there are any extenuating circumstances. Anything will help.

I purchased the new, heavy duty updated nose fork, but the thing looked so ugly, that I haven't installed it. Maybe now I will have to rethink that decision.
It just looks like overkill with all of the additional bracing, reminding me of a stock car field repair, instead of an aircraft engineering project.........Tom
 
I think this is a serious problem

I think this is something there should be a recall on.

Doing a visual inspection on all the area of the fork is not something that will insure there is no crack starting.

The fork breaking and not bending is a serious problem and can cause a very expensive repair or maybe loss of life.
I paid for a front fork for my aircraft and now I should not have to purchase a new one to feel safe.

The RV12 is a great little Aircraft and I think this is a serious problem.
Taking off the wheel pants after a landing to do an inspection is not realistic request.

My View

Joe Dallas
 
I think this is something there should be a recall on.

Doing a visual inspection on all the area of the fork is not something that will insure there is no crack starting.

The fork breaking and not bending is a serious problem and can cause a very expensive repair or maybe loss of life.
I paid for a front fork for my aircraft and now I should not have to purchase a new one to feel safe.

The RV12 is a great little Aircraft and I think this is a serious problem.
Taking off the wheel pants after a landing to do an inspection is not realistic request.

My View

Joe Dallas

The proper way to analyze something like this is to look at the data.

520+ RV-12's flying and only a small handful have managed to fail the nose gear fork.

The nose gear fork as designed easily meets the load requirements for the LSA ASTM. I think the data easily shows that a small percentage of the RV-12's have had occurrences that acceded what the ASTM load requirements are.

Because there is data to show that a small percentage have done that, a redesign was done to give the fork more strength margin way beyond what the design requirements are. It is up to individual owners/builders to decide whether the cost of the updated part is worth the extra margin to them.
 
Taking off the wheel pants after a landing to do an inspection is not realistic request.

Taking the wheel pant off after any hard landing as well as at regular inspection intervals to ensure the aircraft is safe, especially knowing a replacement part is available should the owner wish to beef it up, seems to me to be a very reasonable request. Neither nose fork design fails under normal use/load.

I paid for a front fork for my aircraft and now I should not have to purchase a new one to feel safe.

I disagree with that one. By definition, aircraft must be maintained in safe condition, and part of owning an airplane includes the understanding that sometimes changes are made that cost money. Especially problems caused by over-loading a part, which is what we're talking about here, I think. At some point that fork must have been stressed beyond its limits, either all at once or through repeated over-stressing. I think that's a safe assumption given the data, per Scott's comments.
 
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considered an upgrade ?

Scott is the new fork now included in the new kits
Or is this considered an upgrade

Joe Dallas




The proper way to analyze something like this is to look at the data.

520+ RV-12's flying and only a small handful have managed to fail the nose gear fork.

The nose gear fork as designed easily meets the load requirements for the LSA ASTM. I think the data easily shows that a small percentage of the RV-12's have had occurrences that acceded what the ASTM load requirements are.

Because there is data to show that a small percentage have done that, a redesign was done to give the fork more strength margin way beyond what the design requirements are. It is up to individual owners/builders to decide whether the cost of the updated part is worth the extra margin to them.
 
Fork

I'm waiting for the someone to offer a titanium or stainless reinforced doubler to wrap around the fork as a backup when the fork decides to separate. Not sure if it will help, but it may make some feel better. :)

On a serious note, fairings on our wheels give us additional speed but I wonder if folks don't look under them more often than they should. Things like cracked forks, brakes getting ready to fail, brake lines compromised, and other things may not have the occurances if those fairings aren't removed more often. Just my thoughts. Sorry to hear about your incident. Hope you can get it repaired and back in the air soon.
 
Add me to the list of people who would really, really love to see detailed, close-up pictures of one or more failed forks. I haven't seen one yet.
 
I would guess that MOST of the RV12 fleet has a wheel pant on the nosewheel. This looks nice etc, but it keeps the nose fork from being inspected unless you remove the two piece cover.

I actually do all my local flying with the wheel fairings off just so I can do a better preflight. It lets me see the brake pads, tire condition, brake lines in addition to the nose wheel fork.

To tell the honest truth, I don't care about the speed with local flying, only when I take an extended trip. It only takes about 45 min to put them on.
 
I agree with the "pants off" decision. Since the inspection notice came out, I have not put my wheel pants back on, making it very easy on preflights to take a look. So far, all is well........Tom
 
Agreed! This is a safety issue that costs less than 1% of what you paid for the plane. Suck it up and replace it even if you haven't even used the original yet.
 
Scott,

This begs the question as to whether the ASTM landing gear loads requirements are adequate. Do you think they are?

If you mean to prevent a nose fork failure from ever happening in any single airplane in the fleet, probably.
That is why a reinforced fork was designed and incorporated.

Food for thought though.....

Does the outcome shown in THIS VIDEO indicate that the load requirements imposed by FAR 23 are inadequate?
 
Clearly, the Piper Warrior "wheel barrow" accident does not say that the Part 23 landing gear requirements were/are inadequate.

I agree.
My point is that regardless of what standard you design to, there will be situations where something can still be made to fail depending on how it is treated.
I don't mean to imply that a landing such as this caused the failure that is the subject of this forum thread.
As you know there are a lot of different ways things can fail. A single overload event as in the posted video, or progressively over time because of numerous events where the component was only slightly overloaded .

At the time that the new design nose gear fork was installed on the red prototype/demonstrator for flight test and long term durability testing, the original fork had well north of 1000 hrs. A lot of those hours were doing transition training so it was not because it was babied by a few highly experienced pilots.
It had no evidence of any cracking or developing fatigue failure.
 
Pants off, hubcaps on.

Tom,
I'm with you on this. I took my wheel pants off and put on a couple of hubcaps. When I decide to go on a 400+ mile trip, I'll put them back on but for all the local stuff, those huge puppies are staying off. Some may disagree, but Im not seeing a lot of difference between hubcaps and wheels pants. There is no doubt the pressure recovery wheel pants are more efficient, but not as much as you would think. Especially for local stuff.


I actually do all my local flying with the wheel fairings off just so I can do a better preflight. It lets me see the brake pads, tire condition, brake lines in addition to the nose wheel fork.

To tell the honest truth, I don't care about the speed with local flying, only when I take an extended trip. It only takes about 45 min to put them on.
 
I agree.
My point is that regardless of what standard you design to, there will be situations where something can still be made to fail depending on how it is treated.
I don't mean to imply that a landing such as this caused the failure that is the subject of this forum thread.
As you know there are a lot of different ways things can fail. A single overload event as in the posted video, or progressively over time because of numerous events where the component was only slightly overloaded .

At the time that the new design nose gear fork was installed on the red prototype/demonstrator for flight test and long term durability testing, the original fork had well north of 1000 hrs. A lot of those hours were doing transition training so it was not because it was babied by a few highly experienced pilots.
It had no evidence of any cracking or developing fatigue failure.

Scott, a failure is a failure. It should not have happened.

But it did and it is not appropriate to minimize it.

Like a crankshaft failure, it is unacceptable. The original struts should have been recalled and except for cost, would have been.

Sometimes it is pound foolish to be penny wise. That's what this is all about.
 
Welding

Scott also it could be a problem with the welding on only a few Weldments or quality control

Joe Dallas




I agree.
My point is that regardless of what standard you design to, there will be situations where something can still be made to fail depending on how it is treated.
I don't mean to imply that a landing such as this caused the failure that is the subject of this forum thread.
As you know there are a lot of different ways things can fail. A single overload event as in the posted video, or progressively over time because of numerous events where the component was only slightly overloaded .

At the time that the new design nose gear fork was installed on the red prototype/demonstrator for flight test and long term durability testing, the original fork had well north of 1000 hrs. A lot of those hours were doing transition training so it was not because it was babied by a few highly experienced pilots.
It had no evidence of any cracking or developing fatigue failure.
 
Cracks can be hard to spot on a visual inspection. Is there an additional inspection aid to be had economically/locally?
 
When checking the nose forks on the RV's I have found that cleaning them really well first, and then using a bright flashlight with some 2X "cheater" glasses has enabled me to find the cracks. When I see something suspicious, I will double up on the cheaters and the crack becomes really visible.

Vic
 
Dye Penetrant?

When checking the nose forks on the RV's I have found that cleaning them really well first, and then using a bright flashlight with some 2X "cheater" glasses has enabled me to find the cracks. When I see something suspicious, I will double up on the cheaters and the crack becomes really visible.

Vic

Vic, is dye penetrant a feasible aide?
 
Scott, a failure is a failure. It should not have happened.

But it did and it is not appropriate to minimize it.

Like a crankshaft failure, it is unacceptable. The original struts should have been recalled and except for cost, would have been.

Sometimes it is pound foolish to be penny wise. That's what this is all about.

Landing gear, crankshafts... could be built not to fail under almost any circumstances but I doubt you could get it off the ground at less than 90kts and climb it'd like a 1968 150hp Cardinal :rolleyes:
 
Dye Penetrant Kit

For locations such as this, where a crack is known to have formed, I recommend a dye penetrant test. This is a very simple to perform test that takes only a few minutes and is essentallly:
1. Clean the affected area with included cleaner
2. Spray die on affected area
3. Wipe off excess dye
4. Spray developer
5. Use a nice, bright light and look for signs of cracks.

This should be added to your annual inspection for the nose fork, and possibly the horizontal stabilizer ribs, and whatever else you think might be susceptible to cracks.

Although there are fancy, schmancy kits, this one from Amazon is more than effective at the job: Dye Penetrant Crack Finder Kit by Silver Seal
http://a.co/9ExqvCx
 
In all circumstances anytime the plane undergoes stress beyond what would be normal operation, inspection needs to be performed.

I do realize that this thread began with "nothing abnormal" however it's not the last crack of the hammer that breaks the rock - it's the thousand hits before it. I'm sure most of us would admit to coming close to a limit, be it airspeed, rpm or poor landings.

Having said that, I'm concerned that the immediate response is "user error". This tends to stifle any root cause failure analysis that leads to safer aircraft and engines. It also keeps the community from knowing about a problem and making their own best judgement on how to address an issue.

I see that at rev 3 in 2016 it appears that the "stronger" fork has been incorporated into the kit. My concern is that if it's worth incorporating it into the kit there must have been concern internally and thus the change. So I don't really understand the push back from the manufacture.

I've experienced this on several aspects of the 12.
 
I didn't read Scott was "minimizing", I understood from his post that the nose fork was designed to a standard. The reinforced fork is designed to far exceed that standard I think that is a sign of a great manufacture, we get an ever improved and more robust product.

What I would take away from this is that when buying a plane we should verify with a local A&P that all the service bulletins are complied with. Who knows maybe that would have provided evidence of a few hard landings in this case.
 
I see that at rev 3 in 2016 it appears that the "stronger" fork has been incorporated into the kit. My concern is that if it's worth incorporating it into the kit there must have been concern internally and thus the change. So I don't really understand the push back from the manufacture.

As has already been mentioned, the original design was considered adequate and has proven to be on the majority of the RV-12 fleet.... some airplanes with many hundreds of hours with no failure (The original prototype going well beyond 1000 hours with no sign of failure).

Even with that being the case, the nose fork was still redesigned. I don't see that as a negative. I see it as one more example of effort to make a great airplane even better.
 
As has already been mentioned, the original design was considered adequate and has proven to be on the majority of the RV-12 fleet.... some airplanes with many hundreds of hours with no failure (The original prototype going well beyond 1000 hours with no sign of failure).

Even with that being the case, the nose fork was still redesigned. I don't see that as a negative. I see it as one more example of effort to make a great airplane even better.

I could name several AD's where only a couple planes in the fleet showed a specific problem. That's how it works in the certificated world. We fix them all. Making a statement that most are OK negates the investigation to some extent.

IMO it really doesn't matter if no one saw the problem if it's my airplane that breaks. I want to know why.
 
I could name several AD's where only a couple planes in the fleet showed a specific problem. That's how it works in the certificated world. We fix them all. Making a statement that most are OK negates the investigation to some extent.

IMO it really doesn't matter if no one saw the problem if it's my airplane that breaks. I want to know why.

By we you have to mean it is usually the owner picking up the tab for a fix being forced upon them (and they are not always relevant to all aircraft).
The books are full of AD's that were issued because of just a few high time or heavy use aircraft developed a problem. The books are also full of many that after public comment were converted to periodic inspection and then repair if a problem is found.

In this instance the owner/builder gets to decide.
In the majority of instances where Van's issued a design change as mandatory for compliance, the parts were supplied at no cost
 
For locations such as this, where a crack is known to have formed, I recommend a dye penetrant test. This is a very simple to perform test that takes only a few minutes and is essentallly:
1. Clean the affected area with included cleaner
2. Spray die on affected area
3. Wipe off excess dye
4. Spray developer
5. Use a nice, bright light and look for signs of cracks.

This should be added to your annual inspection for the nose fork, and possibly the horizontal stabilizer ribs, and whatever else you think might be susceptible to cracks.

Although there are fancy, schmancy kits, this one from Amazon is more than effective at the job: Dye Penetrant Crack Finder Kit by Silver Seal
http://a.co/9ExqvCx

I 2nd this advice, the $50 for the kit surely is pennies to check for a crack the way industry would. Visual is ok, but has limitations for sure.


As far as revisions to parts, anybody that has designed a system of any nature, I would surely call an airplane a fairly complex one will understand things are found later that can be improved. If the expectation from consumers is a new design would always come out perfect with no room for improvement, I am not sure anything would ever be done and we would still be riding horses. I personally think Van's does a great job of keeping us informed, offering fixes for free to affordable. This is experimental kit built and I don't remember seeing any warranty being issued. I know that going in, but get the same airplane that cost 3-4x the price in the certified world that still has issues.
 
The books are full of AD's that were issued because of just a few high time or heavy use aircraft developed a problem. The books are also full of many that after public comment were converted to periodic inspection and then repair if a problem is found.

That's simply not true. Airworthiness Directives and Service Bulletins are derived from observations and failures in the field. When warranted through objective data, changes are incorporated into these documents. While AD's may be seen as over-reaching in some instances the goal of these documents is to save lives and protect property.

No matter what the design, engineering, modeling, testing or standards to which a part is created, if it is failing in the field, it is failing in application and warrants scrutiny. A perfectly functioning part is not redesigned and / or re-enforced without good reason. That simply doesn't happen.

My point was to simply expose the callous attitude taken WRT these failures. My entire career was based around Quality Assurance and Failure Analysis. It was my job to champion the concerns of our customers. Thus my bias for safety.
 
No matter what the design, engineering, modeling, testing or standards to which a part is created, if it is failing in the field, it is failing in application and warrants scrutiny.

At what level? Does Michelin revamp their entire tire lineup because one guy has a blowout? You know that doesn't happen - there has to be a certain level of field-failures that can be laid at the feet of the part unequivocally and not on the user before you start a recall/SB/AD procedure. Sticking with the tire example, the Firestone debacle some years ago on Ford vehicles was a good one - the number of failures in the field definitely exceeded "normal wear and tear" limits and we saw the result. Without hard numbers being presented about total units in service, time in service, and failure RATES per thousand hours, there is simply not enough data currently in evidence for anyone to rationally stand up and say there has to be a revision/SB/AD.
 
While AD's may be seen as over-reaching in some instances the goal of these documents is to save lives and protect property.

I wasn't debating the goal, just pointing out that there is often times a failure in the system (and that it seems you are implying that any component failure on an aircraft deserves an AD and correction on all aircraft of the same Make/Model...that is simply not true), but this is getting way off track from the original point of the thread.
I have nothing more to add.
 
I have a couple photos of two different failures, my photo service won't let me post. EMail me at Dongeneda at rgv.rr.com and I will email one to you.
 
Don - I just sent you my email address. If you send me photos I can post them in this thread.

Photos from Don below...

k32a1f.jpg


-

2ise0zs.jpg


-

2h651n7.png
 
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welded alum cracks are bad

fracture mechanics

sc01_zpsad7zrfqq.png


FATIGUE CRACK GROWTH ANALYSIS
=============================
DATE: 29-Aug-17 TIME: 21:04:12
NASGRO(R) Version 8.20 (DLL), January 2017
Final Version
Copyright(c) 2017 Southwest Research Institute(R).
All Rights Reserved.


PROBLEM TITLE
-------------
[no title given]
U.S. customary units [in, in/cycle, kips, ksi, ksi sqrt(in)]

Crack Growth Model: Non-Interaction
Ratio of growth increment to current crack size = 0.0050

Mode of Computations: Regular
(Beta factors computed cycle-by-cycle, if the block is such)

Equation/Table: NASGRO Equation

Material Data Source: User-entered


GEOMETRY
--------
MODEL: SC01 -Surface crack (2D) in finite width plate.

Plate Thickness, t = 0.2500
Plate Width, W = 3.0000


INITIAL FLAW SIZE (user specified)
----------------------------------

a (init.) = 0.1000
c (init.) = 0.2500
a/c (init.) = 0.4000


MATERIAL
--------

Material File Name: NASMF.XMLZ
Material File Description: NASA data/NASGRO eqn (single temp)

MATL 1: 1000-9000 SERIES AL
6000 series
Material 1, Data ID: M6ABA1AB1
Alloy Description: 6061-T6,T62 Al

Alloy Cond/HT: Weld (unk); weld/parallel/as welded; LA
; Room temp


Material Properties:

:Matl: UTS : YS : K1e : K1c : Ak : Bk : Thk : Kc : Keac :
: No.: : : : : : : : : :
:----:-------:-------:-------:-------:-------:-------:-------:-------:-------:
: 1 : 26.0: 23.0: 35.0: 26.0: 1.00: 0.75: 0.250: 45.4: :

: Matl :------- Crack Growth Equation Constants -------:
: No. : C : n : p : q : Alpha: Smax/:
: : : : : : : Flow :
:-------:-----------:-------:------:------:------:------:
: 1 : 0.110D-07 : 3.500 : 0.50 : 1.00 : 1.50 : 0.30 :

:Materi-:---------- Threshold & Small-Crack Constants ---------:
: al No.: DK1 : Cth+ : Cth- : Alpha: Smax/: Small Crk Constts :
: : : : : : Flow : a0 : DKth(s)/:
: : : : : : : : DKth(l) :
:-------:------:------:------:------:------:---------:---------:
: 1 : 1.28: 2.20 : 0.10 : 2.00 : 0.30 : 0.0015 : 0.20 :
da/dN multiplicative factor for matl No. 1: 1.0000

Cth+ = 0, Cth- = 0 are used throughout


FATIGUE SPECTRUM
----------------
[schedule title]

[Note: Stress = Input Value * Scale Factor]

Stress Scale Factors for Block Case: 1

Scale Factor for Stress S0: 1.0000
Scale Factor for Stress S1: 0.0000

Schedule info. was input manually

Total No. of Blocks in Schedule = 1

Block Number and Case Correspondences:
Block Number Block Case No.
From - To
1 - 1 1

Stresses: Remote tension, bending or pin load


FATIGUE SCHEDULE BLOCK INPUT TABLE
----------------------------------
[schedule title]

SINGLE DISTINCT BLOCK


S : M: NUMBER : S0 : S1 :
T : A: OF : : :
E : T: FATIGUE : : :
P : L: CYCLES : (t1) : (t2) : (t1) : (t2) :
----:--:-------------:---------:---------:---------:---------:
1: 1: 10000.00 : 0.00: 20.00: 0.00: 0.00:

Environmental Crack Growth Check for Sustained Stresses (Kmax < Keac) Is NOT Enabled.

FATIGUE SCHEDULE BLOCK STRESS TABLE
-----------------------------------
[schedule title]

SINGLE DISTINCT BLOCK


S : M: NUMBER : S0 : S1 :
T : A: OF : : :
E : T: FATIGUE : (ksi) : (ksi) :
P : L: CYCLES : (t1) : (t2) : (t1) : (t2) :
----:--:-------------:---------:---------:---------:---------:
1: 1: 10000.00 : 0.00: 20.00: 0.00: 0.00:

Environmental Crack Growth Check for Sustained Stresses (Kmax < Keac) Is NOT Enabled.


ANALYSIS RESULTS
----------------

Cycles Crack a Crack c F0(a) F0(c) F1(a) F1(c)

0 0.1000000E+00 0.2500000E+00

# ADVISORY: Net-section stress > Yield and failure is imminent
# (Unless (a) UTS > 2 YS, or
# (b) KIc/YS > 0.5 sqrt. in.(2.5 sqrt. mm.) and bending dominates.)
# at Cycle No. 180
# of Load Step No. 1
# of Block No. 1
# of Schedule No. 1
# Crack Sizes: a = 0.102270 , c = 0.250469 , a/c = 0.4083
# Total Cycles = 180

1.2966945E+03 0.1199672E+00 0.2549738E+00 0.100145E+01 0.826871E+00 0.420013E+00 0.693875E+00
2.3530976E+03 0.1400266E+00 0.2623188E+00 0.964617E+00 0.874795E+00 0.304297E+00 0.701604E+00
3.2677681E+03 0.1602117E+00 0.2728431E+00 0.932899E+00 0.919647E+00 0.192276E+00 0.699955E+00
3.4360837E+03 0.1642572E+00 0.2753987E+00 0.927587E+00 0.928584E+00 0.170470E+00 0.698955E+00

# FINAL RESULTS:
# Net-section stress (Sn) exceeds flow stress.
# Flow stress = 0.5*(yield+ultimate).
# Sn by fatigue load = 24.51, Sn by limit stress = 0.00. Flow stress = 24.50.
# at Cycle No. 3436
# of Load Step No. 1
# of Block No. 1
# of Schedule No. 1
# Crack Sizes: a = 0.164257 , c = 0.275399 , a/c = 0.5964
# Total Cycles = 3436


Execution time (hh:mm:ss): 00:00:00.0
Note: this is elapsed wall-clock time, not CPU time!
 
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This is the old style nose fork? But if I'm correct the NLG leg has not been modified in any version?
 
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direct replacement

I think you are missing the point?

If Michelin stopped making that exact tire ( after the blowout )and replaced it with a direct replacement , there may be a concern ( maybe they learned something ) ( this is where we are at )
My view

Joe Dallas




At what level? Does Michelin revamp their entire tire lineup because one guy has a blowout? You know that doesn't happen - there has to be a certain level of field-failures that can be laid at the feet of the part unequivocally and not on the user before you start a recall/SB/AD procedure. Sticking with the tire example, the Firestone debacle some years ago on Ford vehicles was a good one - the number of failures in the field definitely exceeded "normal wear and tear" limits and we saw the result. Without hard numbers being presented about total units in service, time in service, and failure RATES per thousand hours, there is simply not enough data currently in evidence for anyone to rationally stand up and say there has to be a revision/SB/AD.
 
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