flyrotary@lancaironline.net Mailing List Archive

Message

Well, Rusty,

I did mention that the engine was so tight that it would not idle below 2100 rpm the first run up. It gradually got looser as if something that was causing the friction was wearing down. After approx 2 hours the friction was gone and the engine ran and felt normal.

I find it hard to believe as well, but seeing as how the unlikely continues to happen to me I am getting less hard to convince {:>).

I am certainly open to other hypothesis that explains the two hot spots across from one another. I agree it doesn't seem possible, but it sure looks like something was rubbing and then pushing/cocking the rotor over at that point. My nephew took some photos when we disassembled the engine, but I have not yet received them. I'll post them to the list once I do.

Naturally, I should have pulled the engine apart again - but, in too much of a hurry to get the aircraft home - so I got to do it again {:>)

----- Original Message -----

From: Russell Duffy

To: Rotary motors in aircraft

Sent: Friday, June 24, 2005 1:01 PM

Subject: [FlyRotary] Re: Engine Rebuild - Coolant Leak Cause

At this point, it appears that one of the triangular pieces of the apex seal (could not find it anywhere) left its proper position (undoubtedly during my assembly) and got lodged at the end (apex) of one of the rotors. May have been held their by some combination of the corner and side seal.

Hi Ed,

Are you saying you think the little triangle piece came out of the slot, and was wedged flat between the side of the rotor, and the side housing?

The rotor running clearance is supposed to be .0047" to .010", so 2mm (.0787") seal ain't gonna fit between the rotor and the housing, if that's what you were saying. I would bet that you wouldn't be able to turn the engine at all if you bolted it together that way.

OR, were you saying you think the triangle piece of seal was still in the apex seal slot, but being pushed toward the side of the rotor, similar to having a seal that was too long?

In either case, the wear you would see on the opposite side, would be from the rotor gear, or thrust ring (whichever side that happened to be) of the rotor, since those are raised above the side of the rotor itself. The damage to the side housing would be similar to my oil out I would imagine.

If the triangle piece of seal was missing, I'd wonder if that wouldn't let combustion pressure get behind the corner seals (particularly the side with the missing piece), and push outward creating the extra friction.  Of course I'd wonder why that didn't happen at two places, since that apex seal is on the leading, and trailing edge of two faces of the rotor.

Do you have any pictures of these hot spots?

Cheers,

Rusty