Bending Aft Fuselage Sides

[WaiexN143NM]

hi all,
just read the sbpf newsletter for sept. jeff mentioned a mentorship program. i think its great.
relative to the post in this thread from sam sp1. about bending alum. by heating it first. he bought a partially built sonex. on other threads hes showed pictures of extra holes, misdrilled holes, no rivets etc. ive reached out to him in a PM. i believe any parts that were heated then bent need to be replaced. thanks ryan(and bryan) for offering good advice. ive offered to take a look at sams project.
what do the rest of you think? maybe the factory will chime in on this issue too. are you of the advice of us that these parts NEED to be replaced?

WaiexN143NM
Michael

[peter anson]

As several people have pointed out it is a bad idea to heat structural parts for forming. Heating 6061 at above 200°C will eventually get the material back to something like T-0 temper. Higher temperatures will do it faster. T-0 yield strength is around 55MPa compared with T-6 yield strength of 276MPa, so you can lose around 80% of the strength. The only way to get the strength back is to go through the whole heat treatment process again: heat the part in a furnace at around 500°C for a period followed by a water quench after which the part will naturally age to T-4 strength followed by around 10 hours in a furnace at about 200°C to artificially age it to T-6 condition. Since most of us don't have the equipment to do that Michael's advice to bin the part is correct.

Hope we don't have any heat treatment experts here to tell me I'm wrong, but that process is roughly right.

Peter

[racaldwell]

Sorry folks if you wanted to heat treat your parts yourself. Last month I just sent our last age oven to the scrap yard. It was 50 ft x 10 ft so size would not have been an issue. I tried to give it away with the new owner taking the removal costs but no luck with that.

Rick Caldwell (proj. eng. at Hydro Aluminum)
Xenos 0057

[SP1]

Hi All,
Greatly appreciate you guys chiming in and looking out for me.

My new rivet removal tool is getting its workout, though I'm fitting it in between a very busy work schedule.