New AD for wings.

[Denhamblin]

Originally Posted by larry bowdish

We appreciate the comments made by anyone who has any involvement with Skymasters.
Thank you for sharing with us.

A couple of comments, questions.
First, The New Jersey accident, I thought, involved a Super Skyrocket, a pressurized airplane. I would have assumed that it had the strengthened wing. Do you mean that all pressurized Skymasters don't have the same strengthened wing?? In other words, they are not all created equal.
Second, the straps on top of the wing are only for those aircraft that do not have the 150 gallon capacity wing, and have Flint tanks? Do aircraft that do not have the 150 gallon wing, and don't have Flint tanks going to need this reinforcement?
I have seen on other types of aircraft, a need for a spar inspection. This frequent, and frequently expensive inspection is waived, if there is a spar replacement. Would not a spar replacement, incorporating spar used in the stronger wing, be a better solution than straps on top of the wing??

Thank you,

Larry, the aircraft involved in the NJ incident was a T337G manufactured in 1973. The 150 gallon tanks were offered later though I am unsure as to when. It may have been an option in 1974 and may have been a standard in 1975. I have one customer who operates a fleet of 24 Skymasters and they only fly those with the long wing. From my records they fly both the G and H models. The "long wing' aircraft have "hat" stringers that extend out to WS177. On the "short wing" aircraft these "hat" stingers extend to WS150. Outboard of the "hat" stringers is a spice to a "J" stringer. Additionally, the spar caps on the "long wing" aircraft have a "T" configuration of the spar cap which extends to WS177 and from that point outboard they become an "L" shaped cap. On "short wing" aircraft this transition happens at WS150.

The upcoming AD for aircraft modified with Flint Aero extended wing tip fuel tanks will only be for "short wing" 337s modified with Flint Aero extended wing tip fuel tanks as far as we can tell right now. Until the FAA signs off on our findings we can only speculate but I can say that I am very comfortable with the work of my engineer and the feedback I have received from the FAA on our preliminary findings.If you don't have the Flint Aero tips you would not be effected by this AD. If you have wing tip extensions manufactured by Aviation Enterprises you would be required to follow the instructions in that AD. However, the accident in Avon Park may bring into question the non-modified 337 wing. Since the accident in New Jersey the focus has been only on 337s with extended wing tips.

A replacement of the spar will not be required in addressing the issues incorporated in the forthcoming AD for 337s modified with Flint Aero tip tanks. There may be other ways to address the issue but we think our solution is one that addresses the issue in the most economically feasible way. According to my engineer, and he has been in this trade for many years, this has been done before on other aircraft.