Pretty excited. As some of you may know, I have a 1956 PA-22 tailwheel conversion. In an ongoing effort to improve takeoff performance, I wanted a bigger prop.

The folks at Sensenich were kind enough to sponsor BCP on this one (video in the works), and provided a new W80DM. If you buy one direct, please mention BCP.

This propeller is not STC'd for the PA-22, nor is it approved under the common blanket of "any wooden propeller" that some CAR3 aircraft are. What is STC'd is the W80CM (8-hole version) on the 180hp PA-22 (engine STC by Eddie Trimmer of Willow, Alaska.) What's also STC'd is the W80DM (6-hole) on the Lycoming O-320 on a PA-18 Super Cub. My 337 basically asked the FSDO to interpolate these combinations to arrive at the conclusion the O-320 powered PA-22 tailwheel conversion is a safe modification. They did send it to the Seattle ACO for a coordinated field approval though.

A big question from the ACO regarded prop clearance with one flat tire; I'm on bushwheels, so I had to air down one and measure the prop clearance to the ground.

I can't guarantee your effort will be met with the same level of reason as the Portland FSDO, but I wish you luck. Here's the 337. Not as good as STC but it should get you there with patience.

From the KB page for the PA-20 and PA-22:

https://backcountrypilot.org/knowledge-base/aircraft/162-piper-pa-20-22#modifications

Field approval:
https://backcountrypilot.org/images/kb/aircraft/piper-pacer/337-PA22-Sensensich-W80DM-N6956B.pdf

Also, a big thanks to my mechanic Brian at Steve's Aircraft. Those guys are Pacer gurus and he pretty much walked me through all 3 of the field approvals I've gotten in the last year.

Fantastic news to get that approved!

Come on Zane, you know the rule, no pictures, it didnt happen.

Kurt

Zzz wrote:....This propeller is not STC'd for the PA-22, nor is it approved under the common blanket of "any wooden propeller" that some CAR3 aircraft are. ....

I was kinda surprised about the TCDS.
Interestingly, "any wood propeller" is approved on the 290 powered PA20 & 22,
but not on the 320 powered PA22. Bummer!
Hats off to you for getting that field approval.
What FSDO did you work with?
I got a field approval recently at the Seattle FSDO, but it took 11 months and many emails & calls.
And this was for something simple (26" GY's on my 180)-- much more of a no-brainer than a propeller.
I guess results can vary between individual inspectors at a FSDO,
as much as between different FSDO's.
What are your other two FA's?

Why did you not want to go with the McCauley 82/41or2or3or4 that is STCd for our Pacers? I don't have one on my Pacer mostly because of the expense. Right now I have a Sensenich 74/54 that I really like. I used the McCauley in the past and didn't like the slow cruise speed. I feel the Sensenich that I have now is a good compromise.
Charles

MontanaT-craft wrote:Why did you not want to go with the McCauley 82/41or2or3or4 that is STCd for our Pacers? I don't have one on my Pacer mostly because of the expense. Right now I have a Sensenich 74/54 that I really like. I used the McCauley in the past and didn't like the slow cruise speed. I feel the Sensenich that I have now is a good compromise.
Charles

The Borer is great, and it's longer, but it's twice the weight and a little more expensive.

FYI...don't go any finer than 54 on that 74DM. I was at 56" and it was pretty good, I wish I'd stayed there. I was tempted to eek more takeoff performance out of it, so I asked the prop shop for 100 more rpm. Ended up at 52", which redlines at Vy. Nice climb but it sucks for going straight, and you have to run fairly high rpm to get the aircraft to trim correctly.

I got some neat video footage at NW Propeller of the repitching process though.

hotrod180 wrote:.
What FSDO did you work with?
I got a field approval recently at the Seattle FSDO, but it took 11 months and many emails & calls.
...
What are your other two FA's?

I worked with Portland FSDO, who coordinated with Seattle ACO. It took about 6 months.

My previous field approvals were for gear leg modifications recommended for running Bushwheels (see below), and for a Sutton exhaust. Both were follow-ons. The Sutton was particularly easy because the manufacturer got some sort of blanket letter stamped by the FAA saying that this exhaust was a safety improvement. I'll have to dredge that up.