T-34 to be flying soon

[Dave Siciliano]

At 04:05 PM 4/17/2005, George Braly wrote:

Late on Friday, after an enormous 3 month engineering effort and

multiple many-partied (more than 12, at times) conference calls with

the FAA, we are advised that the FAA has submitted a limited proposed

AMOC for signature approval. Probably Monday or Tuesday.



This will have the effect of getting virtually all (but not all) of the

fleet flying again under maneuver load and speed restrictions.

As a note to the Bonanza Baron world - - if you think for an instant

that these issues are not specifically relevant to your aircraft, which

have nearly identical center spar and wing structures - - you are badly

deceiving yourselves.

>

Frankly, 260 domestic flying T-34's are out there acting as FFL's - -

- 'Fleet Fatigue Leaders' for the entire fleet of Bonanzas and Barons.



Of those, maybe around a dozen (or fewer) T-34's are now in the high

time/high usage category that qualifies them as "fleet leaders" for

the entire fleet of aircraft that share these structural designs and

implementations.



The next time you run into Julie Clark or the Lima/Lima guys, thank

them, will you?



Regards, George

 

[wsuffa]

Dave,

What's the upshot going to be for the Baron and Bo? Is it just going to be a matter of high-time, or are aerobatics a factor?

bill

 

[Dave Siciliano]

Bill:

I'm certainly not the guru on this, but the Bo and Baron have the same type spar carry through assembly as the T-34. Many T-34's have really been over stressed (the warbird encounter birds seem to be working the spar and carry throughs pretty well).

Some with high time show no cracking at the point of past failures (one could presume they've been flown within limits). What George at GAMI did was a lot of testing that found cracking in a manner that had not shown up before. I'm sure We'll get more information soon, but would think at the very least there would be some new type testing and repair under more conservative conditions than in the past.

What's interesting is that a lot of folks have been for limits for the T-34 that would narrow the aerobatic envelope or at least have limited the life of the birds doing aggressive fighter encounter work. The FAA didn't do that. Now that there have been failures, they are taking the position all birds need to be grounded. This seems to include aircraft that have never been used in such aggressive programs. The concern when it comes to Bos and Barons is the FAA will over reach. Birds that have been flown well within limits shouldn't have a problem, but there is fear the FAA will treat these as defective aircraft. Guess we'll see. And I have been focusing on Beechcraft, but, as you know, they are also looking at the Cessna 400 series; if you don't believe the T-34 fix could well affect how they look at the Cessnas, you're whistling while passing the graveyard.

Best,

Dave

 

[John J]

Dave

Thank you for the post. We are going through our spar inspection now and so far so good. Have a C-33 with 3780 tt on it. Got the fingers crossed.

John J

 

[Richard]

Dave wrote,

"The concern when it comes to Bos and Barons is the FAA will over reach. Birds that have been flown well within limits shouldn't have a problem, but there is fear the FAA will treat these as defective aircraft."

Conversations I've had with certain individuals is that there is a strong case that the above will not happen. I am eagerly waiting for the day when George goes public with his evidence.

 

[wsuffa]

Dave,

Well, on newer aircraft - including Commanders - there are life limits. On the Commanders, it's a wing life limit (the one I have has a limit 11,000 hours plus). I suspect that folks asking for that to be lengthened will meet even more FAA resistance....

Thanks for the info. I've been following this and the Cessna limits for a while.

bill

 

[Dave Siciliano]

Bill:

As you are aware, the life limits that were obtained by some manufacturers at initial certification were fairly conservative. Several manufacturers had early limits raised after conducting additional testing and going through the time consuming, expensive FAA approval process. Of course, many models are flying much longer than envisioned by the early design engineers. A lot has been learned about metalurgy and fatigue.

Unfortunately, the P-Baron had an initial certification life of 10,000 hours. With the limited number of planes out there, it is hard to believe anyone would spend the time, money and energy needed to increase certified life even if it has merit. Hope the Commander is the exception.

Dave

 

[gismo]

I'm sure Dave is well aware of this, but for you non-Beech types, the ABS is working very hard to keep the FAA (and Raytheon) from blindly applying the same criteria and burden on Bonanza and Baron owners. There have been a couple of careful analyses done on behalf of the ABS by qualified structural engineers and both concluded that Beech's ideas about most of the existing cracks found in the structure are flat out wrong. Furthermore these analyses suggest pretty strongly that the proposed fix (a doubler applied where the wing attach fittings connect to the carry through) will aggrevate rather than cure the problem. Hopefully this will all get sorted out correctly before the FAA adopts Beech's MSB mandating doubler installation whenever any cracks are found regardless of location as an AD.

I've been kinda holding my breath on this one since the doubler installation runs around $7500 and the supply of kits available from Beech won't cover more than a small fraction of the potential need.

BTW, AFaIK the T-34 failures were all in the wing spar itself, not the carry through, and that spar is quite different than what's in the Bonanzas and Barons.

 

[Dave Siciliano]

Thanks Lance.

You have are much better versed in the way of technical understanding of the issue. You refer to ABS (American Bonanza Society), and they are very involved, but George Braly at GAMI (who is both an attorney and engineer) has dedicated a great deal of time and effort as well as providing testing facilities to isolate the problem and help reach agreement with the FAA. George has some well earned credibility with key folks at FAA and was very instrumental in reaching an agreement (not to take away from the effort of others). There were some folks on a very different track from where this finally wound up. Many of us in the GA fleet that are not on the design, engineering side of things, owe a lot to folks like this.

Dave

 

[John J]

It is a great relief to have our plane, (C-33) pass inspection. Time to celebrate with a nice flight early in the morning.

I know from an inspection on a close friend's B55 Baron 7 years ago. He had to have the doubler kit put in. 12k later and so many calls to Raytheon to get it right. The plane was down for over 3 weeks. His was one of the early ones that was found with cracks. His plane had close to 5k tt a 1965 model. No hard landings or gear ups or any skin damage. How the crack appeared is anyones guess.

John J

 

[Dave Siciliano]

Great news John.
I have a doubler kit installed on my A-36. No notation as to why it was installed in the log book. (This happened before I purchased the plane.) Now, I'm concernted that the doubler kit may not be the proper fix. Guess we're all in flux: those without kits wondering what the preventivie/fix measures will be and those with kits wondering if a change will be required.

Dave

 

[John J]

Great news John.
I have a doubler kit installed on my A-36. No notation as to why it was installed in the log book. (This happened before I purchased the plane.) Now, I'm concernted that the doubler kit may not be the proper fix. Guess we're all in flux: those without kits wondering what the preventivie/fix measures will be and those with kits wondering if a change will be required.

Dave

Dave

Thank you for your note. I would look at the TT and if there is "anything" in the logs that gives a "reason" to put the doubler kit in. Might have been a "hard Landing" some where I know the my friends Baron they found a very small crack on the left side. There was a Hard landing in the book. some 8 years before he bought the plane. I feel like you the doubler kit is not a proper fix. I am going to dig into this as much as I can. When I first saw the kit I felt this is not the way but then again I am not an engineer. I am only a person whp looks at loads and attachment points( must be the farmer in me)

You are so right for we all are in a "fix" The T34 as we know has been around since the 1950's and was used in varioius training roles and in later life became used in some sort of way in aerobatics and instrument upset training. T-34s have had a hard life.

As I look at the plane I too like you am waiting for the next step. I am so glad to have made it this far. I do "soft field landings' as much as possible. Maybe when flying a 39 year old plane I baby it.

Thanks again for your post

Best

John J