flyrotary@lancaironline.net Mailing List Archive

Subject: [FlyRotary] Re: Fwd: Question on RD2-C

I agree that steel rivets would be better than the bolts. I am not certain of the difficulty in squeezing them, but they would provide a “press fit” where the bolts would not. The strength would be similar in shear which is where most of the forces would be. They would also be a lighter, important in a rotating mass.

The difference in mass of the bolts is a small matter and should not be a factor; the assembly is a ‘flywheel’.

The idea of putting something like “Proseal” in before assembly makes sense as well.

Which Pro-seal product do you have in mind? I was thinking maybe JB weld. If you are riveting/bolting this together you don’t want flexibility.

The combination should ensure that shear forces would never move it. In the current situation it must be moving else the rivets could not loosen???

Bill B

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen
Sent: Sunday, March 21, 2010 11:53 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Fwd: Question on RD2-C

The rivets are aluminum.

I find this surprising, as well as disappointing.

I checked the rivets on my RD2-C damper assembly and was able to confirm that they were in fact beginning to loosen as evidenced by the radial streaks on the damper plate. I picked four rivets at random, approx. 90 degrees apart, and grabbed the shop heads with vice grips and tried to spin them. All four would spin with little effort, thus confirming that they were beginning to loosen. After a phone call to Tracy, we decided to replace the ring of rivets with AN3 bolts, which I've now done.

One advantage to rivets is that they fill the holes to zero tolerance. The bolts will be MUCH stronger, but I’m wondering about the potential for some very small amount of ‘play’ to begin with, which would not be a good thing. I don’t know much about steel rivets, but maybe that’s the way to go.

Mark; what nominal length and grip length on the bolts? Are you using standard AN bolts or are there ‘true’ diameter or ‘close tolerance’ bolts available.

Hum-m-m; I just decided I could change schedules in order to fly to the Jean, NV gathering next week. Now I’m wondering whether to fly anywhere before changing out the rivets. I’m thinking that since I see no movement between flange and plate after 180 hours, it should be good for at least a few more hours.