Heat Treatment of 7075 3

[FieldTeam]

I have a leading edge chord made from 7075 .080. It was formed in 0 condition and heat treated to T6. After installing this piece it was found that it was not fitted correctly and required adjustments that should have been made while in 0 condition.
Does anyone know if it is possible to bring this piece back to 0, reform, then reheat treat back to T6?
The question was posed during troubleshooting where it was felt that the adjustment could be made as is, cracked the piece and a new piece manufactured correctly. Many manhours and expense later with lessons learned .... I'm sure a few of you have been there!
Any suggestions would be used in training and debrief.

 

[Aconnell]

I am an engineer at a repair and overhaul facility where we do this quite often. As you stated in your post you need to anneal the part prior re-working and then reheat treat it. The applicable heat treatment spec is SAE AMS-2770G "Heat Treatment of Wrought Aluminum Alloy Parts". If you require I could provide you with the spec.

 

[Aconnell]

I didn't mention it in the last post, but the airworthiness authorities of most of our customers will not accept parts which have been formed in the wrong condition even if no cracking is evident.

 

[Stache]

I have worked with 7075 material several times and it seems to never fit right after the heat treatment. Before the aging process have your tech put it back in the forming mold and reform it, this helps. In the oven the metal will move and twist about changing the part. Reforming should take care of the problem.

Second when installing the part you should have your tech's install it wet with liquid shim. Let it set up 24 hours before installing the hardware.

Stache