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Cowl Piano Hinge starting to Zipper

K

keijidosha

Member
Pulled the cowl for an oil change and found the first three tabs on the upper front side of the upper/lower cowl piano hinge broken off. I heard them clatter into the bottom cowl as I pulled the wire pin out the front.

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I'm the second owner. Can the hinge be replaced? If so, can the damaged segment be replaced or does the whole hinge have to go?

Airframe has 130 hours TT. Also have a call out to get the engine/prop dynamically balanced (better late than never I guess).
 
Last edited:
piano hinge

Matt
you can probably cut off just the damaged section and replace, however alignment will be important. Try to keep it straight by inserting the pin and the other half of the piano hinge when you drill the rivet holes. Drill one hole, cleco it, repeat. You may want to put a doubler over the joint to reduce flexing.
 
Not that big a problem!

Both my RV's have done this. It just screws up the paint job a little. Bean counter has it right. Be sure to use a mini rat tail file and file the inside square corners of the new segment of hinge (stress risers).

Steve
 
Might be worth getting the more expensive extruded piano hinge for this. Van's sells it and so does Aircraft Spruce and probably other vendors. You can get it in the same size.

Dave
 
Pin Size ??

Assuming you are using the undersize hinge pins. The larger ones that come with the hinge put a lot of stress on the eyelets in any kind of curve ....

Bill
 
David Paule said:
Might be worth getting the more expensive extruded piano hinge for this. Van's sells it and so does Aircraft Spruce and probably other vendors. You can get it in the same size.

Dave
Click to expand...

+1
I put an extruded hinge on the left bottom cowl for the same reason. Problem solved.

Carl
 
Hard or Soft Rivet?

To attach the hinge, plans call out AN426AD3-4 (Hard) Rivets. Instructions have a note saying ?when setting solid rivets in fiberglass, use soft (AN426A3-4?) rivets or do not fully set normal rivets." Any advice on preference?
 
Steve Barnes said:
I would use the regular rivets and under squeeze them so as not to stress the glass.
Click to expand...

Also drill 1/4 inch holes in between the rivet holes and embed the hinge material in epoxy when riveting. The epoxy will flow up through the holes and add some strength.

I could hear the glass "creaking" hand squeezing rivets in the old white cowls, but didn't get the same effect in the new, much harder epoxy Pepto-Bismol colored cowl.
 
This tip is more for new builders than repair but it comes to mind because of the above recomendation to buy extruded hinge.

When I was building, I had some 1" long flange extruded hinge in the parts bin. I installed on the lower cowl with epoxy holes per Gil above. I had heard the tip about angling the hinge line for easier install but with the long flange available I decided to raise the complete lower hinge well above the cowl split line. I installed Vans provided curled hinge on the top cowl bedded in epoxy.

After 500 hrs and observing, I think this is a lifetime install. The rolled hinge eyes are supported by top cowl and epoxy vs being free to flex and vibrate at the cowl split line.

Pictures here
 
A little late to the party, but I really like G-Loc epoxy for the hinges, in addition to rivets. It's a bit more flexible than the standard stuff.
 
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