Brief Description: Prop Hub Position - Short Of Spec - Part 1
Before starting the cowling work, I was verifying the engine position with Sonex Tech Support. My engine appeared very well aligned in its position, but my propeller hub face did not reach the proper distance out in front of the measurement reference of the fuselage lower front corner.
I had forgotten that I had not yet torqued the engine mounting bolts/nuts to the Jabiru specified 8 ft/lbs (96 in/lbs). I had waited for this because I did not have any AN-363 nuts, which the plans called for on the engine mount AN4 bolts. I figured I would torque them once I replaced the temporary AN-365 nuts with the final AN-363 nuts.
This also made me realize I would need slightly shorter AN4 bolts rather than the temporary AN4-50A bolts in place right now. Upon a conversation with James Yrineo from Columbus, IN (building an identical Sonex-B), he shared that he and Bill Batten had just received some assistance in properly mounting their Jabiru 3300 engines on the Sonex-B mount from an A&P in their EAA Chapter. It was clarified that the rubber vibration mounts had to be compressed enough to allow the inner sleeve of the mount's T-washer to make contact with the end of the frame's mounting pin tube that is inside the rubber vibration mounts. Once these two pieces are in firm contact, the bolt/nut can be tightened and the specified torque achieved. This allowed me to place these two parts in proper contact, then measure the end points (4.335"), and verify an AN4-47A bolt was indeed the proper size bolt to mount the engine with.
Extra AN-365 washers allowed proper torque to be achieved with AN4-50A bolt temporarily.
