Brodhead Pietenpol Association

I am fab the 0200 engine mount on section AA on the drawing it shows a 7/16 dia bolt my engineer thinks it is 3/8
This is the mount to the engine bolt. John New Zealand.

I have an O-200 on my Air Camper. Your engineer is correct, they are 3/8”. Download Continental Engine Manual Form X-30010 from the internet. You will find the bolt size called out on page 36.
My O-200 case was built to use very expensive Lord Mount isolators but I was able to buy a set of adapters that made it so I could just use the regular cheap conical ones. I’m not sure if Lord isolators need a different size bolt.

What is that crack all about?

It’s a flaw in the casting mold. The lighting from the picture sure does make it look like a crack though.

Whew..

Interesting. Continental definitely recommends a 3/8 bolt here. On my Piet with the O-200, the engine mount is built to the plans with a 7/16 bolt. The mount is extended 3”. Thinking I’m an idiot who built the airplane wrong, I went to check my Aeronca 11ac with an a65. Also uses a 7/16 bolt. Hmm. Both airplanes use the conical rubber bushings as shown above. Aircraft Spruce lists the rubber bushings as .377 id and are a snug fit over the 7/16 bolts. So what then? I guess both sizes work, my Aeronca has 3000 hours since it left the factory, and as of today, my O-200 has survived 12 hours of lugging a Pietenpol around with 7/16 bolts. I’m sure there are other Pietenpols built with 7/16 bolts per the plans as well. Or use 3/8 as recommended by the engine manufacturer.