Thanks Ed, yes I have a tail-dragger and situation is as you stated … will reconsider the gasket.
I have a new tube of Ultra-Grey.
Any comments on the aluminum Front Cover thread repair?
Jeff
(For blind holes).
Where practical, tapping out to 1/4" 20 can be used. Or for the purest, a Helicoil in metric.
(For holes where the back of the hole will be exposed if it were deeper)
If you have a TIG machine, build up behind the damaged hole (inside the cover) flycut the upper end of the hole open. Slip in a metric nut covered with epoxy, tension the nut with with a scew dipped in oil with the excess blown off, and let the epoxy set up.
(For holes where the upper end is clearly open)
Flycut or die grind a flat above the threaded end and just use a nut and a stud. Tension the stud and nut with another nut and epoxy the stud and nut in place.
You could also TIG the hole shut, redrill and retap.
Aluminum is not good at holding onto small diameter screw threads, as you may have noticed. The metric screw threads are just a bit too fine, and can be over torqued with no difficulty. Larger diameter course threads work better. Course threaded studs are best because they eliminate the wear problem of the the screw going into and out of the aluminum hole. This is also why nutserts steel liners and helicoils are better. There wear is between the screw and the steel hole liner.
If the engine is being held into the airplane by just the oil pan screws, I would go over sized on all of them. All studs, epoxied
in place. Course threads in the engine and fine threads through the mounting plate.
I have had to repair many front covers. If you weld on one, bolt it to a front iron, as they are very flexible.
I can make drawings if anyone needs them.
Lynn E. Hanover