Skin Tear

B767Driver

B767Driver

New Member
I have a '75 PA28-151 that's in for an annual. Mechanic found a 4" skin tear between rivets between the landing gear strut and the cabin. (Probably from an airline pilot flaring high and landing hard in a small airplane. Or from 30 years of abuse from student pilots.) Anyway, the mechanic said it is not structural damage but it must be fixed.

This mechanic says that the wing must come off and new skin must be installed ($400). However, I see tons of airplanes around the country with patches covering up this type of tear. (It's a hairline tear separating from 3 rivets). Does anyone here know if this type of skin tear can be patched or does new skin have to be installed? I'll be paying the FAA a visit tomorrow to hear their interpretation, but thought I'd ask your experiences as well...and possible levels of repair.

Thx.
 
Although I am not a mechanic, I think that for $400 I would rather remove the damaged wing skin and replace it than cover the damage with a patch. If you patch the wing, you will still have to pay labor which would be something around $100 (I am guessing here) if it takes an hour to drill holes, fabricate a patch, and rivet the patch in place. And all you will have is a patch to cover your 4" crack. There is no guarantee that the crack will not continue to grow, even if stop drilled (and you will not be able to see it if it does). Reskinning is still relatively inexpensive as repairs to aircraft go and is a permanent fix.

If the crack was to the engine cowling or some other non-structural part, I would say stop drill the crack and cover it with a patch. Since it is on the wing and is a stressed part, I would fix it right.
 
By "tear" do you mean a crack, or something else?

A short crack in the skin running along a line of rivets isn't a big deal if it ends in one of the rivet holes. After the crack reaches the rivet hole, it useually dosent grow any more. You'll need to monitor this carefully for a while.

Your example sounds like it's too long to just let go, and needs a patch. If it is an area of high stress, (ie. right around the gear strut) it may require a patch and/or a doubler.

Pulling the wing and reskining a large area definatly sounds like overkill. Go to a diffrent mechanic and get a second opinion.
 
USMech,

Thanks for the reply. Do you know if the FAA has disallowed the use of blind rivets for exterior skin repair? My mechanic states that the FAA no longer allows them, however, AC43.13-1b makes mention that the FAA can approve on a case by case basis.

The area in question, basically looks like the skin is "pulling loose" from an area of about 3 rivets. It's not actually a crack or a tear....just pulling away from the fasteners.

I have no problem making repairs to an airplane...I just have a hard time believing this item needs a complete re-skinning.

Thx
 
You can use blind rivets in any area where the backside isn't accessable.

Basicly if you can get the bucking bar in an area for a solid rivet, then you should.

It's pretty comon to use a blind rivet before taking off a major piece of the airplane. In your case I personaly wouldn't have a problem useing 3 or 4 blind rivets in order to not take off the wing.

In the end it's mostly up to the mechanic's judgment.
 
If the skin has pulled away from the rivets then the damage actually spans a rib and is considered a major repair. If the skin has pulled away from several rivets there is most likely more wear and damage that can't be seen. It's best to remove the skin to repair any elongation in the rivet holes through the rib or cap strip. If the rivets have sheared, than it is best to remove the skin to determine what other stress damage may exist, and it would be unwise to use blind rivets to replace rivets that have failed in shear.
Second opinions are a great idea, though $400 is pretty darn cheap for a completely new skin that eliminates the damage entirely, expecially on a wing surface under stress.
 
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