Conical engine mount torque

[FORANE]

Wondering what the recommended torque is for the castle nut on a conical mount to engine (o-320). Not the mount to firewall, but rather the bolts through bushings to hold up the motor.

I have googled and come up with references from 40 in lbs to 450-500 in lbs to dimensional specs of 1.84 inches between washers. Just don't know what to think.

 

[Bell206]

recommended torque is for the castle nut on a conical mount to engine (o-320).

What aircraft model? The torque value should be in the airframe MM. I think the 450-500 inch pounds is a Cessna value but not sure.

 

[FORANE]

What aircraft model? The torque value should be in the airframe MM. I think the 450-500 inch pounds is a Cessna value but not sure.

Experimental, Lancair 235/340.

Sure enough, just found chapter 21 of the Lancair build manual. Spec is 1.8 inches between washers - no torque is listed.

 

[Bell206]

no torque is listed.

Just to add, those mount dimensions usually equate to a torque. If they are Lord mounts a quick call to their tech support should get you a torque value if you prefer. Also if Lord there is sometimes a specific stack up by P/N to ensure the best harmonic damping also.

 

[Dan Thomas]

The 450-500 inch-pound figure applies to Dynafocal mounts. They have a steel tube inside them---the bolt goes through it---that the washers seat firmly against. The conical mounts don't have that so the torque is low. Use the dimension.