Warbird Information Exchange

Sorry Chuck, I know you posted this on another thread, but I thought it warrented a new one..

From ANN

FAA Wants Info On T-6s
Deadline For Submissions: June 4th

The FAA has turned to
members of associations like EAA Warbirds of America and type clubs
to gather information relating to T-6 aircraft in the wake of a fatal
accident caused by an apparent wing
failure in Florida on May 9, reported on extensively by
ANN.

At issue are potential wing failures on the vintage advanced
primary WWII trainers following the fatal crash of an SNJ-6 owned
and operated by Warbird Adventures in Kissimmee. Preliminary
examination of the wreckage shows a fatigue crack on the inboard
lower center wing attach angle, which initiated in the radius of
the angle.

The FAA says it has learned of a similar accident in 1975 on a
South African Air Force aircraft. The SAAF ordered immediate and
subsequent 200-hour penetrant inspections of the wing attach
angles,. The FAA is considering adopting the 200-hour
inspections.

This situation may also have an impact on future airworthiness
issues for other vintage aircraft types.

FAA's Airworthiness Concern Sheet (ACS) asks its Safety
Engineers to coordinate their airworthiness concerns with T-6
owner/operators through associations and type clubs. They're
seeking information about maintenance history of the critical parts
involved (inboard lower center wing attach angle), as well as
proposed alternative inspection/repair procedures and their
associated costs.

Owners/operators are also asked to provide any other specific
comments they feel are necessary, including specific examples to
illustrate comments/concerns.

FAA has not determined what type if corrective action should be
taken, be it an Airworthiness Directive or a Special Airworthiness
Information Bulletin (SAIB), or the FAA could determine that no
action is needed at this time. Final determination will depend in
part on the information received in response to the ACS.
FMI: mailto:elawrence@eaa.org

Where did the plane actually fail? Was it definitely the attach angle?

Thanks,

Chris

That article seems to imply that the FAA is a little unsure of what kind of inspection program that they want to implement and how soon they will start. I have been getting calls that there are T-6 owners over in Tunica that are stripping the paint on the attach angles and are going to perform a zyglo inspenction on the ramp so theye are able to race on the weekend. Apparently there will be an emergency AD that is going to ground all T-6s on Friday. They must have heard somthing the rest of us havn't.
I can't say that I really disagree with the FAA implementing this procedure to strip paint off down to bare metal for inspection. On one T-6 that I license every year we have changed both lower inboard attach angles over the last three years. Ours were due to corrosion (exfoliation). I think that by forcing people to strip and examine this area they will find quite a few bad (corroded) angles. I hope they include into their inspection to replace any bolts that come into contact with paint stripper. There are types of stripper that cause hydrogen imbrittlement in steel.
This is going to be a major inconvienienc to the T-6 community but we have to remember that a couple of guys just got killed by this.

If this is the direction that we're headed I see nothing wrong or excessive about it. Wing attach angles have always been an issue in the T-6, and an area that we look at closely at each inspection. Besides problems with corrosion we've seen other T-6s over the years that had several loose or broken bolts. Obviously if the bolts are loose (or absent) the loads cannot be properly distributed over the attach angle.

Chris, I guess they're referring to the "L" junctions of the wings, the ones with holes that are riveted to the wing surface.

Alex

i dont like to sound rethoric, but I guess our birds are often considered too resistent, and often many ppl think that a hand of paint can solve any problem(I've heard "we'll think about it later" too many times..).

Alex

I don't think that statement is true at all, and in fact I think it's absolutely wrong. I would venture that most of the T-6s and SNJs in the world are maintained to a very high level by owners, pilots and mechanics. In fact, given that many of these airframes have gone through extensive restoration and care as values have risen and supply has decreased (compared to 30 or 40 years ago) I believe that these aircraft have never been better looked after.

well.. I was referring to "birds" in general Steve.. I've seen a lot of crap in GA and ultralights too, I wasnt particularly referring to the T-6.. Btw if memory serves there has not been a single structural failure during the service years in the Italian Air Force, so all in all the military service planes weren't treated that bad. We must remember about the age of the structures, even when the spares we use are NOS (they might be a 60 years old NOS..). The case of the T-6 is really peculiar: as many other training machines she has been used (and abused) for decades, so despite the robustness of the structure we always have to use extra care when operating old and vintage planes. As a ground chief told me once "U'll never be zealant when overhauling an old plane".

Alex

..and u'll agree with me that an improper mantainance operation on a part of a plane can cause more damage than benefit. Btw, u would be amazed by the conditions of certain machines flying around europe..

Alex

Seems to me like a one time inspection might be warranted of SOME airframes for the purposes of data gathering (maybe the type clubs could suggest volunteers?), but I doubt that a recurring fleet inspection would accomplish much except to keep the dye check companies in business.

The article doesn't note whether it was the right or left side that failed or what the aircraft's damage history was, so you don't know if maybe a groundloop caused the damage or perhaps some other event.

Removing the attach angle covers and inspecting for loose bolts or corrosion should be part of every annual inspection already, right?

I for one would like to see the metallurgy report for the failed angle and the damage/maintainance history of the aircraft.

Alex, I have no idea what you're trying to say. This thread is about the T-6 accident in Florida, and more specifically what inspection actions might be required to try and prevent an accident like this from occuring again. Please limit your comments to that subject and refrain from the "Oh, I've seen some terrible maintenance in GA and ultralights". Sorry, but I don't care about ultralights at the moment, and certainly not in this thread. Comments like yours do nothing to help the warbird movement.

The Concorde had a 100% safety record until it was discovered that if you ran over a sharp piece of metal at high speed a tire could shread and puncture the wing fuel tanks. If testing shows that the T-6 has a fatigue problem at the wing attach angle we'll fix it and go on. Now, do you have anything specific or germane to that issue?

..ok steve, I didnt mean to go off topic or something, my point was about the fact that sometimes we are not 100% careful, otherwise such accidents wouldn't occur. As u said the wing junction on the T-6 is one of its most delicate areas, and such accidents are just a sad reminder that we always need to pay extra care when operating and overhauling such old machines. There's nothing much to say I think, if u dont agree with me I can't help it, but I guess this doesnt allow u to define my points as "absolutely wrong".

Alex

Alex, you are absolutely wrong. Your statements that "many people think that a hand of paint can solve any problem" and "I've heard 'we'll think about it later' too many times" suggest that negligence is a contributing factor to this accident. You're wrong. There's no evidence to support your statement, and lots to support the opposing viewpoint.

Your statement that "sometimes we are not 100% careful, otherwise such accidents wouldn't occur", is an insult to both the owner and the victims of this tragic accident. This is the same bullsh*t we had a few months back, when people were trying to tell warbird pilots we were unsafe for flying without helmets. I don't need penguins on the ground telling me the risks I take flying warbirds, I'm well aware of them. And for that matter I don't need you telling us that this accident could have been avoided if only we had been more careful. What would you suggest? Ground all aircraft? That would keep them safe (although a tad dusty).

Alex, you are absolutely wrong. Is that clear enough?

While it is tragic what happened, this the the first T-6 I have ever heard of having structural failure of the wing. The airframe is built to handle alot more than what most operators have put them thru. The Brazillians used to routinly exceed VNE when they were doing thier large formation loop and the only failure they had was front windscreens letting go. I read the inspection procedure that Warbird Adventures is recommending and I find it to be VERY excessive and in some respects scary. Jacking a 6 with half the lower wing attachbolts removed is scary, since the jack points are on the outer wing panels, not to mention wear on the bolts, in my shop a wing attach bolt is never reused, nor is the fiberlock nut. The Airframe is all ready covered by a corrosion inspection AD, and the attach angles are inspected at each annual/condition inspection, also removing the paint is asking for more corrosion, either from leaving the attach angle unprotected by paint or by the chemical action of paint strippers used to removed paint, or improper paint removal. With the average 6 being flown 25-50hrs a yr, there is no need for a inspection that might occure every 4 yrs or more, and in that 4 yrs, the attach angle would have been inspected 4 times or more.

I have worked on and restored over a dozen T-6/SNJ/Harvards,from the AT-6 and SNJ-2, thru the T-6G and Harvard IV, and of all those I have found 1 attach angle with exfoliation corrosion, and no cracks, and all are flown in acrobatics.

I would like to know where the Warbird Adventures 6 failed, was it at the bolts holes or rivits, cracked in the radius of the angle ? Was the plane ground looped, over G'd ? How many hours on the frame and how many in air combat ?

Matt Gunsch,
A&P,IA,Private Pilot
Crew Chief of TBM-3E, DC-3C, B-25J, PBY-5a, T-6, T-28, PT-17
Riding member of the
2003 world champion drill team
Arizona Precision Motorcycle Drill Team

I inferred from the recommended inspection of removing half of the bolts, doing a dye pen, and then reinstalling and repeating with the other half of the bolts that the area of concern is in the bolt holes themselves. I don't think you would need to remove the bolts to get a good look at the radius.

By jacking the aircraft with half of the bolts you should be in no danger. You are only at one "G." The shear loads should be taken by the attach bolts on the spar while tension loads go into the lower attach angle bolts.