RV-12 accident - August 2017

[Fearless]

There was a failure on a 12 based out Bowman Field here in Louisville recently. His failed making a turn off the runway at a different airport. Fortunately the wings come off to make transporting the plane back less painful. He suffered damage to more then just the nose wheel. I don't think he follows this forum.

[Jim T]

Originally Posted by snopercod

I'm just a nobody, but to me, the nose wheel assembly shown in that first photo appears really under-designed. I realize the the RV-12s only weigh...what?... 750 lbs. but even so.

What I see in that first photo is a nose gear that has had the living **** beat out of it. Lots of paint missing and what appears to be grass stains on the front.

Jim

[waterboy2110]

The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000 providing the engine is OK (it should be). That's cheap insurance if you're using craggy airports like Rensselaer.

[BigJohn]

Originally Posted by waterboy2110

The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000 providing the engine is OK (it should be). That's cheap insurance if you're using craggy airports like Rensselaer.

I agree with above. Jim is a good and smooth pilot, but Rensselaer's runway has been in terrible shape for years. I speculate (there, I said it!) that this failure was the result of metal fatique induced by many many stress cycles. I agree that anyone who operates routinely from rough fields ought to consider the "cheap insurance". Even though I only visit grass or rough fields occasionally, I think I will replace the fork at the next CI. JMHO.

[JRo]

530 hours on the aircraft. I'm the only one who's ever flown it, and it's never had a hard landing or nose wheel landing. Seems to me like the fork is a really weak point & poor design. Damage resulting from this failure is extensive. Had the aircraft pole-vaulted as the strut dug into the runway, I'd have been trapped upside down and likely unable to evacuate the aircraft as the canopy rested on the surface with the full weight holding it shut.

[snopercod]

Originally Posted by waterboy2110

The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000...

I'm old, so I've noticed along the way that some people are funny that way with their money. The guy in the hangar behind me owns a Lightning with similar nose gear. On a test flight he muffed a landing badly - ended up in the weeds - and curled back the lower part of the gear. I advised the guy to buy a new fork from the factory but instead he just had a shop beat it back into shape. That kind of thinking (or non-thinking) is foreign to me.

[BillL]

Originally Posted by Steve Melton

fracture mechanics

FATIGUE CRACK GROWTH ANALYSIS
=============================

I am not sure what this means precisely, Steve, but would certainly agree that running some 2-3-4 cycle drop test is not adequate for evaluation of a fatigue failure. Fatigue loading tests, FEA, and Weibull analysis of field failures to indicate percent of population that will fail is the way to properly address this as an issue. Being aluminum they will all fail eventually, but the design life here is not known. Even the design targets are not known, but I doubt the target is ZERO for an infinite life.

It looked like that test began with a crack and ran 180 cycles, did it then fail?

[BillL]

Originally Posted by rvbuilder2002

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.

As for Scotts comments here, in this forum - - in my view:

Scott posts here as a courtesy to we builders and owners. He is not to represent the official engineering analysis and decision making of Vans as a whole. I take his comments in that context and not as an absolute or complete justification for the Vans official position. Some of his arguments are clearly insufficient to make this engineer happy, but that is beyond expectations for his participation on this forum. We politely take what we get and if we don't like it, pick up the phone and call Vans, or send an email. It just seems rude to attack our only source of any enlightenment here and cause his blood pressure to rise.

Something to think about, put yourself in his position.

I have nothing more to add

[joedallas]

My View
This forum is a great way for all of us to present our view and concerns.

Scotts participation is impotent to help understand a different view.

His view is of his opinion only and not necessarily those of his employer ( he has made that clear )

This is a great way to communicate with vans and let them know our concerns.

The community on the whole is better than anyone persons view.

I am sure that vans is aware of the problem and only they can decide the extent.


MY view

Joe Dallas

Originally Posted by BillL

As for Scotts comments here, in this forum - - in my view:

Scott posts here as a courtesy to we builders and owners. He is not to represent the official engineering analysis and decision making of Vans as a whole. I take his comments in that context and not as an absolute or complete justification for the Vans official position. Some of his arguments are clearly insufficient to make this engineer happy, but that is beyond expectations for his participation on this forum. We politely take what we get and if we don't like it, pick up the phone and call Vans, or send an email. It just seems rude to attack our only source of any enlightenment here and cause his blood pressure to rise.

Something to think about, put yourself in his position.

I have nothing more to add

[Piper J3]

Originally Posted by waterboy2110

The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000 providing the engine is OK (it should be). That's cheap insurance if you're using craggy airports like Rensselaer.

I looked up New Version WD-01230 12 NOSE FORK CONVERSION and it appears the going price is $325.00

Oh well...