Rear lift strut failures???

[Benbell4140 0]

Hello, I've read of two cases where the rear wing strut threaded attach rods have failed on avids. The rear strut on the left wing is the only strut that I see that has a threaded rod end where it connects to the rear wing spar. Is this something to be cautious about? Anyone have any problems? Is there any way to fix this potential problem? Just trying to be aware of things like this. I know they say no structural failures ever recorded but this seems structural to me.

Thanks for any info!

[dholly 718]

Hello, I've read of two cases where the rear wing strut threaded attach rods have failed on avids. The rear strut on the left wing is the only strut that I see that has a threaded rod end where it connects to the rear wing spar. Is this something to be cautious about? Anyone have any problems? Is there any way to fix this potential problem? Just trying to be aware of things like this. I know they say no structural failures ever recorded but this seems structural to me.

Thanks for any info!

Well, I would submit any nut or bolt is a 'potential' problem waiting to happen. Two failures of a single part in probably 2000 aircraft is inconsequential IMO. And, at least in the case of the UK Avid, I think it is well documented the part likely failed as a result of some other prior 'bending' causal effect:

"The lift strut is effectively pin-jointed at both ends. Therefore, the flight loads can only induce either a tensile or a compressive load in the threaded rod. However, this rod had failed in bending. The rod had therefore either failed due to impact loads or it was bent prior to flight. If the rod had been bent prior to flight, then a compressive load acting during the takeoff roll could have caused the rod end to buckle, resulting in a bending failure."

The most important take-away from the accident report for me was that the compressive and tensile loads necessary to snap a rod end are so high there is a very large safety factor. The deadly culprit it would seem is bending load and the most likely cause (absent a hard landing or ground loop etc.) might be from improper tie down, particularly when trailering. Since many trailer their Avid and Kitfox, it is definitely something to be aware about. As for the odds of in-flight failure out of the blue, I sure wouldn't loose any sleep over it unless the aircraft has a prior damage history. Be thankful your Avid has only one adjustable rod end, my KF III has four!

Avid Lift Strut Rod End Failure.pdf

[jackak 20]

Check out the Avid flyer site on Yahoo, Steve Winder discussed this some time back. You'll have to research the messages.

Jack

[Benbell4140 0]

Thanks guys, just wanted to make sure no AD's were issued for this.