Sparrowhawk vs. RAF PSRU Prop Pulley

dunc

RAF/Sparrowhawk/SC 2.5 FI
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Crawford, CO
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1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
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Although my pulley bearings have a "tight" fit into the pulley, there seems to be a few that suggest that the pulley be machined for a steel sleeve be installed to prevent possible wear and dissimilar metal corrosion between the outer race and the pulley. These include:

Mike Burton: https://www.rotaryforum.com/forum/k...sparrowhawk-gyroplanes/24068-sh-psru-upgrades

Brian Willis: https://www.youtube.com/watch?v=CYXftOzQ-AU

This seems like a good "preventive" measure and I am likely going forward. However in the video, a external sleeve is stalled for strength for the internal bearing. My SH pulley shaft is tapered, per the attached rough sketch, making this external sleeve problematic for the interior bearing area. Of course the taper could be machined to square for adding the external steel sleeve, but this would weaken the aluminum assembly and possibly make a stress riser. A good view of a RAF pulley is seen at 2:02 into the video. This looks like the RAF pulley shaft is square throughout, and possibly welded to the pulley wheel portion?

??? My question to your gyro experts is whether this is another difference between the SH and RAF pulleys. Your overall opinion on this sleeving modification is also requested.
 

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CLS447

Platinum Member
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Reading, PA
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Air Command 503 & Air Command SxS /EJ2.5
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Aprox 400 gyro
Rob !!!! Read my post under the engine thread......Don Parham has his info posted there.....Please support him .....he is a world of info. Always happy to chat about gyros & Subarus..
 

dunc

RAF/Sparrowhawk/SC 2.5 FI
Joined
Aug 1, 2016
Messages
177
Location
Crawford, CO
Aircraft
1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
Total Flight Time
5000
Don and I had a good chat last week, and identified my engine so i could purchase the proper manual. He is "fully retired" per his words, but does not mind talking a bit.
 

CLS447

Platinum Member
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Messages
6,321
Location
Reading, PA
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Air Command 503 & Air Command SxS /EJ2.5
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Aprox 400 gyro
That's great , Rob ! Could you share what you learned & give us an update on the progress ?

Thanks !
 

dunc

RAF/Sparrowhawk/SC 2.5 FI
Joined
Aug 1, 2016
Messages
177
Location
Crawford, CO
Aircraft
1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
Total Flight Time
5000
No Title

I was told that any PSRU pulley with a circumference notch, like mine, was fabricated by RAF. Those without are SH. So my pulleys are fine as their anodizing is nearly perfect, thus no bearing spin. However due to negligent prior maintenance, my prop/jackshaft is about - 0.0005" undersized and RAFSA allows for - 0.0000 so I will be purchasing a new shaft for $152 and eccentric for $95. Shipping and delivery schedule is currently TBD. If I want them anodized, that will cost more and delay shipment by at least another two weeks. I will likely keep the majority of my progress, questions and concerns posted on the RAF forum thread. At least I get some responses there and I suspect most of my issues will be stock RAF issues.
 

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CLS447

Platinum Member
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Messages
6,321
Location
Reading, PA
Aircraft
Air Command 503 & Air Command SxS /EJ2.5
Total Flight Time
Aprox 400 gyro
I'm glad that you can get the parts ! I wonder if SH parts are available ?
 
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