Propeller Help

[akchamp]

I was planning to install a Sensenich M76AK-2 on my 7AC Champ with an 65 Continental. This is an approved prop for an A-65 and according to the Champ type certificate (TC-A-759), it is also listed as approved for the 7AC with the provision that the static r.p.m. and diameter limits are the same as for the fixed wood pitch props (NTE 2250 r.p.m. and be between 70 and 72 inches long). My Sensenich is a stock 74" long. Does this mean I have to cut this prop down to use it and be legal? I sure don't want to butcher the prop. I know some of the 74" McCauley's are legal. Maybe I'm going to have to trade this one off.

Thanks.

[sevenacjack]

According to the sensenich tech's at the metal prop plant in Pa. on a M76AK-2, the -2 means you can cut it down two inches and make it a M72AKXX, but to be on the safe side why don't you call them at: 717-569-0435, and ask for doug ?, I did mine that way and now have a A65 7AC with a M72AK44 that performs great!!!, much better than the three wood props I had on it before. Jack

[Al Hatz]

I was planning to install a Sensenich M76AK-2 on my 7AC Champ with an 65 Continental. This is an approved prop for an A-65 and according to the Champ type certificate (TC-A-759), it is also listed as approved for the 7AC with the provision that the static r.p.m. and diameter limits are the same as for the fixed wood pitch props (NTE 2250 r.p.m. and be between 70 and 72 inches long). My Sensenich is a stock 74" long. Does this mean I have to cut this prop down to use it and be legal? I sure don't want to butcher the prop. I know some of the 74" McCauley's are legal. Maybe I'm going to have to trade this one off.

Thanks.

Do not cut it down. You want all the diameter you can get. The 74" M76AK-2 is the ideal prop. When they talk about the 72" to 70" limits they're talking about the wood propeller limits. They're only talking about the rpm range limits on the M76AK-2.

[Al Hatz]

According to the sensenich tech's at the metal prop plant in Pa. on a M76AK-2, the -2 means you can cut it down two inches and make it a M72AKXX, but to be on the safe side why don't you call them at: 717-569-0435, and ask for doug ?, I did mine that way and now have a A65 7AC with a M72AK44 that performs great!!!, much better than the three wood props I had on it before. Jack

The (-2) on the M76AK-2 prop means it was already cut down 2" from the standard M76 propeller at the factory. It came from the factory at 74", that's all it means.

[sevenacjack]

Yes, I stand corrected, thats what I intended to convey, mine started life as a Sensenich M76AK44 and I had it cut to a "M72AK44-4" this puts it in the proper A-759 TCDS RPM range for all operations, a longer prop could limit the RPM's according to the folks at the Sensenich propeller plant in PA. which makes sense to me. FWIW, Jack

[Al Hatz]

Yes, I stand corrected, thats what I intended to convey, mine started life as a Sensenich M76AK44 and I had it cut to a "M72AK44-4" this puts it in the proper A-759 TCDS RPM range for all operations, a longer prop could limit the RPM's according to the folks at the Sensenich propeller plant in PA. which makes sense to me. FWIW, Jack

Sensenich model number assignment can get confusing.
As for the Champ, the range allowed for 74" M76AK-2 is 2250-1960 and most A65 should be able to static that unless you're trying a 48" pitch. Even if it doesn't quite make it to 1960 you're still better off with the 74" prop on an A65.