Airworthy?

It looks like a fairly easy repair by cutting out the wrinkled area and splicing in a new piece, WTF anyone would be flying it that way or admitting they flew an unairworthy airplane is beyond me.

$20 in metal, $400 engineering, $150 paint, and a bunch of elbow grease.
 
Henning said:
Can you cite where that is an option?
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any ACO could help you out with that. :D

If conformity can not be determined with the original cert basis....a re-test of an article can be an "acceptable means of compliance".

Part 23 reads (but this is probably a CAR 3 aircraft)
§23.681 Limit load static tests.

(a) Compliance with the limit load requirements of this part must be shown by tests in which—
(1) The direction of the test loads produces the most severe loading in the control system; and
(2) Each fitting, pulley, and bracket used in attaching the system to the main structure is included.
(b) Compliance must be shown (by analyses or individual load tests) with the special factor requirements for control system joints subject to angular motion.
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There is no mechanism or technical data to use a load test to verify structural integrity of a damaged component. Load tests are only used to verify structural integrity of repaired or altered structures, such as when shoulder harnesses are installed using AC41-13-2B as reference. Or when moving batteries to new locations.

This is a simple situation and there are typically six steps to follow:

1- We have an obviously damaged airplane.
2- Evaluate the damage in accordance with approved methods
3- Formulate a repair in accordance with approved data, or with an engineer.
4- Perform the repair exactly as the data specifies
5- document the repair
6- return the airplane to service.

Forgot to mention...hammering aluminum back into shape causes work hardening. You have weakened skin where it was bent, hardened skin where it was hammered, and the intersection of those points is where the failure will begin. Now the 2024T3 is no longer in the strength range it was intended to be, because you have a mix of high and low strength areas in close proximity. Along with uneven thickness due to the hammering. Remember, this skin is only .025" thick to begin with.

Loosely translated, you have an area with a high probability for failure under load, for stress concentration cracking, and most likely death of the occupants when it does fail in flight.
 
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Geeze....you all are wayyyyyyy to technical!!!

Fly it until the tail falls off.....then u can fix it!!!:dunno:
 
Perform this simple experiment to convince yourself this plane is unsafe.

Take two identical beer cans. Empty them. Dent the side of one, then fix the dent.

Place them side by side in a vertical position. Stand on the undamaged one. It will hold about 150-180 pounds evenly distributed.

Stand on the damaged one. It will fail under the same load.

The Ercoupe empennage is no more complex of a structure than the beer can.
 
Okay, I just drank a dozen beers to make sure I had plenty of cans sitting around to experiment with.

What's the next step again?
 
timwinters said:
Well,

I've decided that it's not a concern regardless of what all you engineers and airframe experts say. In fact, I went flying in it yesterday and it flew fine! I mean, after all it's

"only skin"

Cosmetic only IMO.
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rbridges said:
Just my 2 cents. Not an engineer or mechanic. IMO the skin adds strength to the structure. Even in dentistry, there are restorations that in themselves are pretty brittle but become stronger when attached to the structure below it.

I'm not saying it's not airworthy, but I would assume the plane is not as resistant to flex/deflection (whatever the proper term is) than it was prior to the accident.
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But it flew just fine! The only thing I noticed is that if you let go of the yoke, it would immediately enter a standard rate turn to the left!
 
timwinters said:
Okay, I just drank a dozen beers to make sure I had plenty of cans sitting around to experiment with...
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Me too but wait... he said cans?

Darn, I'm gonna have to start over.
 
so, let me get this straight.....you drank a dozen beers and went flying.....and it kept turning to the left? :eek:
 
Yeah, but I wasn't the anonymous poster over in Medical Matters!!!!

I've never been uncoordinated, rather just mis-coordinated!
 
timwinters said:
Yeah, but I wasn't the anonymous poster over in Medical Matters!!!!

I've never been uncoordinated, rather just mis-coordinated!
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Yep, and I've never been lost, I have occasionally temporarily misplaced myself though.:D
 
timwinters said:
The side of the empennage on a local Ercoupe. It was initially damaged when a hangar collapsed on it and appears to have simply been "beat back out" into shape.

The damage is on one side only.

Considering the monocoque construction...is this airworthy?


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OK, let's say it's heat treated aluminum alloy, such as 2024-T6.
being bent will weaken the overall structure. being beat back out will stress the area that was bent and allow cracks to develop. I would suggest replacing that portion of skin.
Now, if that skin were properly anealed, beat out, and then re-heat treated, all would be well. But I seriously doubt that's what happened here.
 
timwinters said:
Okay, I just drank a dozen beers to make sure I had plenty of cans sitting around to experiment with.

What's the next step again?
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taxi around the airport and see if you get arrested. then you can answer another question for someone.
 
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