Bulent Aliev wrote:

I had a conversation this morning about that with the owner of Fighter

Enterprises in Ft

Lauderdale. He maintains and repairs Mustang P-51's  mostly. He thinks even

5/16 is over kill.

Also in the Cozy the thrust forces are against the Barry mount, and not against

the bolt, like

the tractor config. Also I looked at a Mooney mount. Again 1/4" bolts  on the

firewall and the

thrust works against the threads on the same bolts?

Wow. My Cessna uses 3/8 or 7/16 I don't remember exactly which.... maybe 1/2
inch.

Push or pull matters not in a six G pull up or a hard landing.

Are you using the "rubber bushing in the firewall trick" Bulent? If not
then are we talking about the bolts holding the steel mount to the firewall
or the bolts going through the rubber bushings mounts out near the engine?
If out near the engine the bolts are in a bit of bending mode while the
ones holding the steel mount to the firewall are mainly in shear and
tension. That makes a difference. I personally would not use 1/4 or 5/16 bolts
anywhere in the engine mount. Not worth the risk for such a small increase
in weight.

Paul Lamar

Bulent Aliev wrote:

The Barry mounts are on the firewall [Image]

I added the loads that cause bending in the bolt.

Paul Lamar
 
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