Originally Posted by
EXDAC
To torsional rigidity of Piper rag wings is low. Just like the high wing Pipers, the PA-25 has a one lift strut connected to the front spar and one lift strut connected to the rear spar. The lift struts control the twist of the wing as well as supporting the lifting loads.
There have been several PA-25 AD on lift struts and the fuselage lift strut attach cluster. It will be interesting to learn if this accident aircraft was compliant.
That makes sense, didn't think of wing torsion. I am decent with the classic mechanics, but never got any engineering education. To me it looks like a very sharp pull up, followed by the wing folding up, fold line from the leading edge/fuselage to trailing edge/lift strut, with the wing folding backwards as well as upwards. That would be a failure of the front lift strut. We will find out if the maneuver was outside of the envelope and/or the maintenance was the problem.