Calling all A&P's...What are your thoughts on this crack?

stevenhmiller

stevenhmiller

Pre-takeoff checklist
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Steve's Archer
I pulled the door off my 77 Archer to replace the door seals. After cleaning it up and painting it, I tried a dry fit without the seals first. I noticed the door was not closing and was binding at the bottom hinge area. When I proceeded to close it, it would kind of feel springy as if the inner door frame were pressing against the door opening and not allowing it to close. Upon closer inspection of the door, I found this stress crack. So, apparently it's been like this for a while.

What are your thoughts on the door? Any way to fix the crack, or do I need to replace the door all together? Also, I need to find out what is causing the binding, otherwise it will happen again, I'm sure.

20151025_124014.jpg
 
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Stress crack caused by work hardening of the area. As the door was opened and shut for the past 38 years it flexed that edge. Work hardening causes the metal to get stronger and harder, but it also make it more brittle, less ductile, and less tough. The aluminum no longer likes to bend and it eventually fractures (cracks) when flexed.

But that is not what you are asking. You are asking what you need to do about it. I'm not an A&P and cannot answer that.
 
what to do?.....well the crack will not get any smaller and left alone will continue to grow until the stress is ultimately relieved.

I have no idea how long that door will go....but eventually it will need to be replaced or patched. I can't tell by the picture if it's repairable.
 
Does the crack appear anywhere on the other side?

Also, I always like to play the mind game, WCS: worst case scenario. If that is a crack, and it rapidly elongates, was is the worst that could happen? Just in case someone continues to fly it. I have no idea in this case...can't see the crack real well, don't know the associated structures.
 
If it weren't an airplane, I'd be drill stopping each end of the crack, JBWelding it, sanding it flush, and then partying on while keeping an eye out for further running of the crack. But, it's an airplane.
 
Thanks for all replies. I'm replacing the door. not worth the risk. It's at the hinge and only going to get worse.
 
inclined to agree if it's at an attach point, WCS means the door could depart.
 
When you say " it's been like this for awhile" do you mean springy and not closing right? Because it's entirely possible that you didn't get it put back on right and created that crack right then and there. It looks kinda new in the picture.
 
The area around the crack is very clean. Was there fretting residue? Other than that, it doesn't look new to me, it is black down in the crack. If it were new you'd see aluminum.
 
GlennAB1 said:
The area around the crack is very clean. Was there fretting residue? Other than that, it doesn't look new to me, it is black down in the crack. If it were new you'd see aluminum.
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The picture was taken after I had removed the old door seal, cleaned with adhesive remover and sprayed with zinc chromate. During all that, I hadn't even noticed the crack!
 
Not to be nit-picky but you should realize that spraying zinc chromate over existing paint is a complete waste of time.

As for the crack, and I believe you already mentioned this, you need to find what is causing the binding or you're just going to crack your new door as well. Just be careful when test fitting because you can induce a lot of stress on that spot without realizing it due to the large lever advantage you have. What may feel like a slight bind could be putting an unacceptable amount of force on the hinge attach point.
 
Silvaire said:
Not to be nit-picky but you should realize that spraying zinc chromate over existing paint is a complete waste of time.
Click to expand...
I know that. I had bare metal, so that is why the zinc chromate. I simply taped and just did the whole rim.

Silvaire said:
As for the crack, and I believe you already mentioned this, you need to find what is causing the binding or you're just going to crack your new door as well. Just be careful when test fitting because you can induce a lot of stress on that spot without realizing it due to the large lever advantage you have. What may feel like a slight bind could be putting an unacceptable amount of force on the hinge attach point.
Click to expand...

I know what caused the crack. The bottom hinge is bent outward. This was apparently existing damage, as nobody uses the door to balance when getting in or out of the plane. And the door was carefully removed, so not bent by me.
 
Sounds like you are going down the right path.
Now you just have to decide what to do with the old door. I vote for using it as the door for a kids fort or playhouse!
 
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