engine mount bolt part no. and prop spacers

sanships · Post by **sanships** » Thu Dec 15, 2005 6:21 am

Looking for the engine mount bolt part no. for my series aircraft. I have the old one but my mechanic suggests that we change all with new ones since I still have the originals and showing signs of wear.

I lost the prop spacers, P/N 35954( moisture impervious plate) and 35955( propeller retaining flange). Anyone know where I might find one? Anyone have spares? Thanks!

Post by **GAHorn** » Thu Dec 15, 2005 4:55 pm

Alvin, are you looking for the bolts that attach the engine mount to the firewall? (lower bolts are AN6-33A and upper bolts are AN6-22A, using AN365-624 nuts)? These are airframe parts found as items 2 and 9, in Fig 49, in the Cessna Illustrated Parts Catalog for the B model. You should own a copy. (Your mechanic is required to have one in most circumstances. If your mechanic is unable to identify exact parts on your aircraft, you might want to consider whether he is really qualified to do that work.)

Or are you looking for engine parts? Are you wanting the AN7-27A bolt which attaches the mount at/to the engine? (item 6, Fig 50.) The associated nut is AN365-720 and the washer is AN960-716.

Alvin, you do have a metal propeller? The prop plates to which you're referring are applicable only to wood props.

sanships · Post by **sanships** » Thu Dec 15, 2005 10:13 pm

George, I was looking for the engine mount to the engine bolt. Thanks! I do have the parts catalog but my mechanic is confused on serial number differences. He is not computer savvy and it is left to me to find the proper part numbers thus the reason for these questions. It is costing me a lot more educating myself and my mechanic especially when there are only 2 flying 170's here and the other one has the avcon conversion, but I should have almost all parts and flying soon.

I do have a metal prop but have the skull cap spinner. The mechanic says that the bolt sticks out the back a bit more than expected( about 1/4"). Thus the suspected backplates. Is there a required spacer or washer that can be put on to reduce the space? How much of the bolt can stick out? Thanks!

Post by **GAHorn** » Fri Dec 16, 2005 7:37 am

As long as the bolts do not interfere with adjacent structure (such as the cowl) then there should be no problem. But the bolts for the prop (a different problem than that asked in this engine-mount question thread) that were mentioned elsewhere were for the larger spinner.
If you have the IPC, then all the bolts are listed there. Keep in mind that the prop bolts will not likely retreat towards the cowl inflight. (The engine/prop combination are what pulls the airplane forward. They are unlikely to move aft except in extreme circumstances of deceleration.)
I do not know of any specification for minimum clearance, but 3/4" between rotating parts and the cowl are commonly quoted in data I've read.

sanships · Post by **sanships** » Mon Dec 19, 2005 3:47 am

George, my mechanic needs confirmation that there are no backplates needed for the metal prop installation. Where can i find the data that states that in the IPC or other manuals. Thanks!

Post by **GAHorn** » Mon Dec 19, 2005 11:55 am

Alvin, the IPC illustrates it. See pg 79. and pg. 145. Are you sure your mechanic has seen propellers before? It sounds like you need to obtain the services of another.