Cruise Prop on a 1956 Cessna 172

[Bill G.]

I have a fantastic 1956 Cessna 172 thanks to Steve Johnson and my wife working together last year to buy it for me as a surprise.

I use the plane for short (less than 300 mi) cross country travel.

I suggested to my mechanic that I could install a cruise pitched prop. He suggested that I simply send my old prop off to be re-pitched.

My questions is this: Since re-pitching a prop requires bending the metal, doesn't this cause some weakening of the prop which would make it more likely to fail? Wouldn't purchasing a new cruise pitched prop be a safer option than bending a 50 year old prop?

Finally, the current prop on my airplane is polished, as I understand it, that is a no, no as far as the FAA is concerned.

Thanks in advance for your thoughts.

Bill Gilbirds

[Steve Pierce]

I asked the owner of the local prop shop about fatique in bending a prop. He said they are soft enough that it won't effect them. The polish debate is about the manufacturers overhaul procedures calling out etching, alodineing and the proper painting procedure. The prop shop can do all the work and call it a repair and not an overhaul and you can keep your polished prop. They are pretty but a lot of work to me since everyone wants to touch them.

[SJ]

Bill,

Frank Spatz up at Atchison does a good repitching job, I've had a couple done. 913-367-1872. I was just up there the other day dropping off a prop that I sold. Which BTW, would not fit in a husky due to the baggage configuration, but would have fit fine in my supercub...

sj

[zane]

What is your prop currently pitched to? I think the stock MacCauley is is 53", with the cruise prop being 56". Makes for a faster plane in cruise but I'm not sure I'd want to give up what takeoff performance the 145hp 172 has.

[WWhunter]

I agree with TripSlip38. I have either a climb or cruise/climb on my 1960 172 with an 0-300. I had thought of doing the same as you but changed my mind. And I'm glad I did. I have flown mine over quite a bit of the US and on a long cross country it would make a differnce but I really enjoy the flying and scenery. If your trips are normally less than 300 miles I really see no sense in changing it. It will not make that big of difference, plus, just think, you get to spent a little more time flying.
Enjoy that 172. Even though I lust for a SC you can do so much with that 172. They're easy to fly, economical, and anyone can fix it.

[CraigH]

Bill,
I'd wholeheartedly agree with the two post above. I had a '56 170B with a standard pitched prop. While climb was decent solo, it left something to be desired loaded on a warm day. Climb is not something I'd want to give up for the few mph you'd pick up with a cruise prop.

[behindpropellers]

Bill-

What is your cruise right now?

100 kts is typical for ours, 95KTS without the wheelpants on.

Tim

[Bill G.]

The reality is my cruise at 2400 RPM without wheelpants is already 100 Kts. I think the comments about preservation of climb are very good. I am going to try flap gap seals and aileron seals first. I'm not big on wheel pants, but I realize that I would gain a few knots that way. I will report on my improvement in speed after the modifications.

Bill Gilbirds

[CraigH]

Bill,
My 170B had 8.00 series tires with no pants. 115mph was about it for me in cruise. I've heard mixed reviews on the flap gap seals. Supposidly you'll pick up some speed, but the flaps won't perform like they did before the seals. Several of the guys on the 170 site mentioned that they didn't care for them. However, I'd HIGHLY recommend the Horton aileron gap seals. I put the tape seals ($105 with STC) on my bird and it made a tremendous difference in low speed aileron feel. Best $100 I ever spent on the plane!