Pat wrote:
Just out of curiosity, with the advent of the recent wing attachment Airworthiness Directive, what are the costs of the new parts required under this AD? How many hours of labor would a reputable shop need to complete it?
Currently there is an AMOC for the upper attach angles allowing for inspection every 1000 hours after the initial 200 hour inspection. The lower angles still have the 200 hour inspection interval.
We have replaced close to two dozen attach angles on T-6s in the past year. All of these have been from intragranular corrosion and not from cracking. In fact, I do not believe that additional cracks have been found in the fleet that underwent the initial AD.
There is a long standing AD on the attach angles for corrosion. In my opinion this has been long ignored, based on amount of bad ones we have found. In my opinion, and this is based only on the ancedotal data that I have from watching my crew tear down a number of T-6s this last year, NAA had a heat treating problem. This has led to a lot of their extrusions having intragranular corrosion problems. We are finding this in the wings and center section as well.
I think there will eventually be a change in the interval for the attach angle inspection. I am not sure how I really feel about that given the amount of corrosion that has been found on the angles. Would everyone be taking such a close look at the angles if we weren't forced to do this 200 hour inspection? Before I bought Midwest Texans I was one of those who was convinced that the wing attach AD was completely overblown. After what I have seen in the last year, I am a true believer that they need to be examined carefully corrosion...as do a number of other extrusions in the airplane.
Yes, I realize there is an AD already covering the corrosion issue, but as I mentioned above in my opinion it has been largely ignored over the years. I have personally seen a number of T-6s over the years where it was obvious the wing attach angle covers hadn't been off the airplane since it was painted. The recent AD, of course, changed all that. But we have found corrosion on angles that passed the recent AD, but the corrosion issue was still not addressed.
There are no 'new' attach angles at this time. The only ones available are sixty year old NOS parts. It is a time consuming process to replace the angles.