1952 PA22-135 Prop Change Needs a Spacer?

[tankman]

Backing_Plates_20231114_132250.jpg

Replacing the damaged prop with a M76AM-2-57. The previous prop was a M74DM. The issue is that the previous prop was approximately 3 1/4 inches thick at the hub. Uses 4 1/8 inch bolts. Replacement prop is approximately 2 1/2 inches thick at the hub. Acquired 3 5/8 bolts. The issue is the thinner prop hub is moving the front backing plate back 3/4 inch and the front spinner screw holes will not align.

What are the options?
1. Acquire a spacer plate 3/4 inch thick to go between the front of the hub and behind the front backing plate?
2. Fabricate a spacer plate 3/4 inch thick to go between the front of the hub and behind the front backing plate?
3. Do I have the wrong prop?

Thanks,

[Gilbert Pierce]

Both of those props are eligible under PROPELLORS and PROPELLOR ACCESSORIES, item #2 in the PA22 TCDS O-290 and O-290-D2.
https://dyzz9obi78pm5.cloudfront.net...23d5/n/1a6.pdf

[Vagabondblues]

Backing_Plates_20231114_132250.jpg

Replacing the damaged prop with a M76AM-2-57. The previous prop was a M74DM. The issue is that the previous prop was approximately 3 1/4 inches thick at the hub. Uses 4 1/8 inch bolts. Replacement prop is approximately 2 1/2 inches thick at the hub. Acquired 3 5/8 bolts. The issue is the thinner prop hub is moving the front backing plate back 3/4 inch and the front spinner screw holes will not align.

What are the options?
1. Acquire a spacer plate 3/4 inch thick to go between the front of the hub and behind the front backing plate?
2. Fabricate a spacer plate 3/4 inch thick to go between the front of the hub and behind the front backing plate?
3. Do I have the wrong prop?

Thanks,

That prop is thinner because the cord is longer, 76 inches rather than the 74 inch on the DM. The -2 following the 76 means it was reduced to a 74 inch diameter at the factory. The thinner cord profile is why the hub is also thinner. The 76AM is subject to many service bulletins and one AD for cracking due to the thin profile or cord. If you have it installed with either 290 engine, D or D2 you are subject to a repetitive AD and a required to have a placard restricting RPM. The 76AM also uses the shorter stubby spinner.

[Steve Pierce]

You need the spinner for the M76AM-3 prop.
https://www.univair.com/piper/piper-...ly-fits-piper/

[dgapilot]

Don’t forget that the 76AM prop has an AD that is required each 25 hours to inspect and repair any nicks, gouges or scratches within 8” of the tip.


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[smcnutt]

Backing_Plates_20231114_132250.jpg

Replacing the damaged prop with a M76AM-2-57. The previous prop was a M74DM. The issue is that the previous prop was approximately 3 1/4 inches thick at the hub. Uses 4 1/8 inch bolts. Replacement prop is approximately 2 1/2 inches thick at the hub. Acquired 3 5/8 bolts. The issue is the thinner prop hub is moving the front backing plate back 3/4 inch and the front spinner screw holes will not align.

What are the options?
1. Acquire a spacer plate 3/4 inch thick to go between the front of the hub and behind the front backing plate?
2. Fabricate a spacer plate 3/4 inch thick to go between the front of the hub and behind the front backing plate?
3. Do I have the wrong prop?

Thanks,

You need the spinner for the M76AM-3 prop.
https://www.univair.com/piper/piper-...ly-fits-piper/

Don’t forget that the 76AM prop has an AD that is required each 25 hours to inspect and repair any nicks, gouges or scratches within 8” of the tip.


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Sounds like that may be a "maybe". While not legally, but from a practical and financial aspect. YMMV

[tankman]

Thanks for the quick replys!
Univair is out of stock.

Anyone have a u13661-a spinner?
thanks,

[dgapilot]

Wag aero sells a Colt spinner that will work. That’s what I got for my Clipper.


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