New Prop

[flynlow]

I sent my M76A M-2 50 pitch Sensenich to a prop shop to have repitched to 48 and got a call that the shop couldn't legally work on the prop.
It was explained that my prop needed to be replaced because of age. The prop looks great and the cub only has 1000 hours. The logs don't reflect when the prop was installed.
The cub is a 1952 PA-18-125 with a o290 D. I believe I could install a Sensenich 74DM6 48 pitch prop. My M76A weighs 24 lbs and the 74D would weigh 32.
What are the options....i don't believe the Borer prop is available for the O290. I want a climb prop and live at 2500' .

[S2D]

For starters, the PA-18-125 with that prop is only is only approved with a 50 pitch.
Did the Shop say they couldn't overhaul it either.
Try Jim Fix in Lincoln NE.
You don't say where you are, but I've never heard of a prop shop say they couldn't work on one cause it was too old. ( maybe they meant they couldn't repitch it without a complete overhaul.)
but if you do get it repitched, remember you won't be legal without saome type of approval for the pitch change.

[flynlow]

I talked to Jim Fix as he was driving up I 24 somewhere on his way back from Sun and Fun.

The prop shop (not Jim Fix) did say the prop was too old, he was a bit vague. I wanted it pitched from 50 to 48 but that wasn't the issue. The manager was going to fax me some material about the problem.

Jim told me my prop was a early prop with thin tips. He was driving and I didn't want to get too involved but I got the impression that the prop may be have been too light (thin) and had some failure problems I'll contact him again in a few days when he gets home. I here that Jim is a very good source for prop issues.

I just was wanting to know if any one knew of any options other that the 74D sensenich prop for a good climb prop.

[flynlow]

I found the AD pertaining to my prop, at least it concerned the O290D2 and I am sure the O290D is included . The 76AM2 prop was to be removed from service due to reoccurring tip failures. That is basically what Jim Fix was telling me as he was cruising down I 24. This directive was obviously missed or ignored by numerous annuals on this airplane.

[Pilk]

I have the76am50 on my 0290d this air craft is exp cub. I also did not know about the AD mY BOOK shoughs a74dm for an 0290 our in amcauley it has a GM8241 . I asked about this once and iwas told igould put aGM7448 ON .if anyone knows weather this right or wrong lit us know.

[n4873a]

I have a 52 pitch for sale. 11.6 hours on it since overhaul. I removed it for a Borer. $1000 plus shipping.

[S2D]

I have the76am50 on my 0290d this air craft is exp cub. I also did not know about the AD mY BOOK shoughs a74dm for an 0290 our in amcauley it has a GM8241 . I asked about this once and iwas told igould put aGM7448 ON .if anyone knows weather this right or wrong lit us know.

McCauley has an STC for putting their prop on the O-290. Last one I did, McCauley just sent it to us Free. course that was quite a few years ago.

[flynlow]

S2D
Is the STC for the GM7448 prop.
Jim Fix told me the O290 didn't have the power to swing a borer prop.

[S2D]

S2D
Is the STC for the GM7448 prop.
Jim Fix told me the O290 didn't have the power to swing a borer prop.

I can't remember the exact prop, but it was 74" and not the borer prop.
As far as the AD:

Regulatory Information

54-05-02 SENSENICH: Applies to All Model M76AM-2 Propellers Installed on Lycoming Models O-290-D and O-290-D2 Engines.

Compliance required by March 15, 1954, and at intervals not to exceed each 25 hours operation thereafter.


To eliminate the possibility of blade tip failures on Model M76AM-2 propellers installed on the above Lycoming engines, all nicks, gouges and scratches within 8 inches of the blade tip should be removed. Care should be taken to be sure all trace of the damage is removed. Minor damaged areas may be removed by using coarse emery cloth. The repaired area should then be polished with fine emery cloth. Rebalancing is not necessary when repairing minor damage areas as defined in Civil Aeronautics Manual 18 (18.30-15)

(Sensenich Service Bulletin No. R-2 covers this same subject.)


Don't see anything in this AD about removing the prop from service.

[flynlow]

I just got this from sensenich as a response from my question concerning why my prop shop wouldn't work on my 76AM prop.
My question was why the prop wasn't legal on my cub, esp. since this was the original prop installed when new.





Steve,

Actually the propeller is legal, just not recommended any longer. I have two Service Bulletins and one Airworthiness Directive for you to see here:

http://www.sensenich.com/service_r2.htm

http://www.sensenich.com/service_r3.htm

http://www.sensenich.com/ad540502.htm

The bottom line is that you absolutely must keep those leading edges free of any stress risers. I can also say that switching over to the 74DM6 series propeller is not only safer, but it is a more efficient propeller. Most customer stay with the same pitch as their 76AM series propeller for better across the board results.