(Leon McAtee) wrote


It's probably not carrying any loads. A basic tenet of structural
design is that the stiffest load path carries the load, and the bolts
through the angle and into the case (secured with nuts and washers
inside the sump, before the engine is assembled) seem a bunch stiffer
that the epoxy.

Been there, done that.

Oooh, that's what I like! Experience...

The epoxy is more of a feel good thing. File
the sides of the sump flat, spot face the inside surface and bolt the
thing together with the bolt heads inside (no washers). Use some blue
Locktight on the heads and torque to the normal specs for the
fastener used and it won't leak.......at least that's been my
experience. A bit of Ultra Grey silicone doesn't seem to
hurt, as long as you get things torqued before it sets. You want good
metal to metal contact so things don't move around.

Why no washers? The little bit of radius at the root of the shank of
the bolt needs somewhere to go, yes? And may I assume you're putting
these bolts in a reamed hole?

That got me to thinking. Taper pins.

http://assist.daps.dla.mil/docimages...3/28/54217.PD4

Threads on the outside. I'll have to run the reamer in from the sump
side, through the aluminum angle and control the depth pretty
carefully.

I need to measure the thickness of the case walls to get the grip
length right, but I'm thinking an AN-386-2-9A from AS&S should do the
job. http://www.aircraftspruce.com/nsearch.php?s=taper

Another way to make the metal carry the load would be with locator
pins in reamed holes (called Shuffle pins when they're used on the
split line) to take the shear loads. I think with the tools and
tooling I have, the taper pins will be easier.

As for the corrosion issue, I haven't had any problems and I've
adapted this method to my ground bound VW's for attaching home brew
block heaters to the side since the old style oil sump things are so
hard or impossible to find anymore. If the corrosion isn't a real
problem driving on salted roads it shouldn't be a problem on an
aircraft.


All the above based on my personal experience only
==========================
Leon McAtee
Still looking for Aeronca C-2/3 factory drawings