----- Original Message -----
Sent: Wednesday, July 13, 2011 8:30
AM
Subject: [FlyRotary] Re: RD-1B
failure
There's a lot of history of this type of drive
plate failure. It occurred on the Lou Ross psru with some frequency. I did
measurements and analysis of the Lou Ross, then some experiments to prove
cause and effect. Here's what I learned:
The drive plate has tremendous strength in the
rotational axis, but very susceptible to fore/aft movement. All of the cracks
are consistent with fatigue failure fore aft direction. In addition, the Lou
Ross had symptoms which forecast drive plate risk. The width of the
spline wear on the input shaft was a direct measure of how far the shaft moves
fore aft. So if the spline on the drive plate had 1" of contact with the
mating spline, yet you saw spline wear on shaft to be 1.25" wide, that was
proof of 1/4" movement. In addition, this movement rapidly caused grease to be
extruded from the little pilot bearing at the end of the input shaft. So you'd
see grease streaks after only 5 hours of use. Looks like you don't have these
same predictors, but I thought it was valuable to explain all of the
supporting evidence.
Fuel combustion causes explosion which sends high
energy pulse to drive train. Since the gears are helical, a portion of that
energy is transferred into fore aft movement of the input shaft. Excessive
clearance at the end of that shaft allows greater inertia of shaft. Beating on
drive plate like a hammer. The input shaft is steel, the psru housing is
aluminum. They don't expand the same amount when heated. As a result, the Ross
psru had excessive clearance during operation. Getting rid of this excess
clearance dramatically improved Ross design. No more loss of grease on that
little pilot bushing. No more wide wear pattern on the input shaft spline. No
more failure risk.
I think you guys are using a pretty good psru.
Very likely you have this same problem.
----- Original Message -----
Sent: Tuesday, July 12, 2011 4:17
PM
Subject: [FlyRotary] Re: RD-1B
failure
David, I
have seen this multiple times in the auto repair business, as far as a
cause, on cars that someone had removed trans & did not reinstall
all the retaining bolts, improper alignment of trans/eng., guide pin
missing, trans bolts loose, damaged when trans installed (pry bar nicks all
over the flywheel caused cracks) found a rag installed between trans &
eng., & also on NEW cars with low miles no previous repairs
performed. I also found
three Mazda auto trans flywheels as Tracy did, with very fine cracks around
the lightening holes ( not the bolt holes ) when we were looking for
one to use on our RV6A rotary. I even asked the salvage yard guy
to check for me & he missed them & shipped me that junk
flywheel. David R. Cook
RV6A Rotary, Lansing MI.
From: "David Leonard" <wdleonard@gmail.com>
To:
"Rotary motors in aircraft"
<flyrotary@lancaironline.net>
Sent: Tuesday, July 12, 2011
6:27:57 PM
Subject: [FlyRotary] Re: RD-1B failure
Left over
pieces of flex plate - we being held together by ???
--
David
Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.nethttp://RotaryRoster.net--
Homepage:
http://www.flyrotary.com/
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