O/T Fire

I understand your perspective that the plane is safe and might agree with you if we were talking about a farm implement going 5 mph, but it's an airplane and we really don't if it's safe or not.

Unfortunatly advice like this could kill someone.

I would approach my inspector after I had built a case one way or the other.

Given the length of the fire, I would be very suspect if the worst case scenario is any more than certain skins need to be replaced. I know that is bad outcome, but not as bad as totalling the machine.

Life is about managing risks - ya don't want to take unnecessary ones, but we are all heading west at some point.

Tip

I'm interested in how they do the tests. I'm guessing that they use some sort of eddy current instrument, since directly measuring conductivity would require puncturing the paint and cladding.

Despite the various posts to the contrary, I am optimistic about the outcome. Aluminum is such a good conductor of heat that I doubt the aircraft got that hot. (The cowling, being fiberglass, couldn't dissipate the heat. And plexiglass doesn't have to get very hot at all to distort.)

I don't know anything about materials testing, but I'm pretty sure this would effectively be a destructive test: The part under test would have to be stripped of its coatings and (more importantly) its pure aluminum cladding.

Is there perhaps an inspection plate you could sacrifice in the area you suspect is damaged? Or perhaps one of the wing skins. It seems to me that it would be worthwhile to ship it off to a testing lab. You might not get a conclusive result, but if the lab says the part is still at T3 you could decide then what other testing you want to do. If, on the other hand, the part fails, then you should seriously consider scrapping the airframe.

A static load test is the only way to know if the spars have weakened. Even if you reskin the aircraft, you could have structural members that are annealed. Of course, load testing the wings won't ensure that the empennage hasn't been affected.

Personally, I'd rather collect the insurance, assuming it's insured.

Did you come to a tractor site because you thought you might get a different answer than Van's Aircraft gave you?

You don't want to hear this, but I think you have absolutely NO WAY to know how hot the skin of that plane got, much less the internal structure. If it got over 200degrees, you could end up with am annealed condition O airframe or somewhere in between, which would be like flying a wet noodle. First load would result in permanent deformation of the airframe, knocking everything out of alignment. Whatever pitch, yaw or roll set the wings, tail or horizontal took would be there, all the way to the ground. I may be fine or it may not, are you willing to bet your life on it?

I do hope you had Hull insurance because this is the time to call it up. That's just an absolute crying shame.

From what you given us the plain has been essentially in an oven for at least 10 minutes at a temperature between the melting point of plastic with some parts at the and bubbling point of paint but less than the melting point of aluminum.

I've heard some concerns about power coating aluminum and that the temp required to bake in the powder coating could change the temper of aluminum. In this situation I would think you exceeded that temp on some part of the plane. The problem is how do you physically test an entire plane like this to insure it's safe. I wouldn't rely on one part being a representative sample. Cowling at 500, wing tip at 200 unpainted surfaces at 900, who knows.

You might want to ask the guy that was about to inspect the plane for airworthiness and get his read. He is on site and can guide you better.

I feel for you.

Sorry with the bad news.

Advisory Circular 43.13-1A, Chapt 2, Para 98 c. says "Reheating of 2017 and 2024 alloys at temperatures above that of boiling water after heat treatment, and the baking of primers at temperatures above that of boiling water, will no be considered aceptable without subsequent complete and correct heat treatment, as such practice tends to impair the oirginal heat treatment."

Many steel parts inside the airplane, such as rudder bars, hinge fittings, etc are probably still useful, and I would bite the bullet, strip if of all reusable parts, and scrap the aluminum structure.

Charles

X-ray won't help you. What you need is a temper inspection with hardness & eddy-current testing.
Trust me, I worked with & taught non-de-structive testing for many years at the Boeing Co.
Check around your area for NDT labs.
Vern