Propeller Mount

From the 912 Series Installation Manual, Chapter 61-00-00, Page 4, Propeller Shaft System Limit.
Extension of the Propeller Shaft:   Maximum 120mm (4.72")

Sam, I have removed the prop and cleaned the hub in the area of the "crack". I see no sign of a crack now. I did not have my magnifying glass but am going back tomorrow (2/16) and will check again to be sure.

My prop extension and new bolts and self-locking nuts should be here Monday, 2/20.

Thank you Bill,

I have purchased a 1.1in extension and mounting hardware from Warp Drive today and UPS says it should be here in 4 days, 2/20. We'll see.

For anyone following this because you are also new to the amateur built world and are interested in options, the "extension" pictured in this conversation is not an option. I mentally questioned this installation before purchase, but decided that a DAR had approved this and it had been flown for 180 hours. I really wasn't thinking very well that day. I have no way of knowing what has taken place, but I doubt that this installation was approved and that it has operated 180 hours. Anyway, I hope this helps someone else avoid such a dangerous situation.

When I removed the propeller and mounting hardware, the 8mm bolts were bent and the threads in the steel mounting lugs of the drive flange were so worn that the bolts could be shaken when screwed into the lugs. The lugs are supposed to fit into the propeller hub and and take the shear (rotational) forces of turning the prop. The bolts are just supposed to handle the tension load of the propeller's pulling the airplane. In the picture, the propeller hub is sitting a face plate that is sitting on the end of the drive lugs. The bolts do not have nearly the shear strength of the steel drive lugs into which they screw.

In addition, there was nothing to hold the propeller centered on the drive plate.

I have purchased the correct extension and mounting hardware from Warp Drive today and it shipped today (Wed.).  UPS claims that it will arrive Monday. The cost of materials and machine work would be more than I paid for all the correct stuff. Luke, at Warp Drive was extremely helpful and nice.

I greatly appreciate the fact that no one started their comment with a well deserved "Hey, stupid!" Thanks to all.

Bert you did well to trust your instinct and ask for assistance and advice. Next have someone familiar with your plane give it a thorough inspection.