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Broken Cowl Pin

Bud K

Well Known Member


I was pulling the cowl off to perform maintenance when the end of piano hinge pin holding the upper cowl to the bottom broke off. I have to twist hinge pin from the stowed position in order to pull it out. It broke off just as the pin enters the hinge. Fortunately, the end of the pin extends beyond the hinge at the firewall. I was able to reach around and push it out enough to grab the broken end and pull it out. Dodged a bullet. I wasn't sure how I would remove the pin otherwise.

Anyone else have this type of problem?
 
McMaster-Carr

My pins were to tight so I ordered a few thousandth smaller pins from McMaster-Carr. Been working great for the last 5 years.

Multipurpose O1 Tool Steel
Tight-Tolerance Rod, .0850" Diameter, 3' Long
88645K78
__________________
 
A bit of graphite on mine, and they go in and out without problems.

- mark
 
In our shop, we polish the pins with scotchbright and then rub them with Boelube on a regular basis. Keeps them operating smoothly.
 
20 years without a snag here.

Mine don't have those somewhat sharp angles in them except at the very ends, and they look smoother. Your pins are stainless, right? Depicted pins almost look like aluminum from here.
 
Mil Spec or SkyBolt

I HAD problems with Hinge pins in general......
Installed new cowl and used all 1/4 turn fasteners.
Looks so much more professional...Love it!
The hinge pins now look kind of homebuiltish...(is that even a word?):rolleyes:
 
I have pins and love the "CLEAN" look! I can have all 4 of my pins out in less than 5 min but I clean them every time and rub Boe Lube on them!
 
I have the side pins come out via the cockpit. Keep them clean and a very light lube and they go in/out with hand pressure. Make sure you have a locking device.

Carl
 
A couple of thoughts:
- you can "bore out" the hinge loops to make pin insertion easier. Take an extra hinge pin, heat one end to red hot, and then beat it flat - enough to make its dimension larger than the pin diameter. Then grind it off to flats (with sharp corners) on two sides. Insert and spin it with a power drill through the entire length of each side of the hinge connection (top and bottom in your case). I used this approach on both of my horizontal cowl hinge pins and it solved the tightness problem.
- use Boelube every time you reinsert the hinge pins. It helps a LOT.
 
Lube

My cowling pins are stainless. I always install them with lube to ease installation. The end that broke off was because I have to bend it to unlock it from inside the cowl. I am just glad it wasn't the left side. I don't want to think about how I would have gotten that out. It certainly would have caused some fiberglass repairs. :(
 
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