My Acro II is powered by a Lyc O-320 160 HP swinging an aluminum Sensenich 74DM6-0-57. The prop was bought used without a logbook with questionable pedigree but it looked fine. There was a sticker on it from an out of state prop shop hinting that it had some work done to it. Visual inspection showed that the hub had been drilled for 7/16 prop bolts rather than the model numbers specified 3/8 bolts. Other than that the prop looked okay with the exception of some minor leading edge erosion and paint issues. I planned to test it on the plane and at some later date return it to Sensenich for inspection and reconditioning.
325 hours later the prop had provided great service. The plane climbed at 1300 FPM @ 85 MPH at 2700 RPM (solo) and cruised at 115 at 2450 RPM. I had planned to send the prop for service earlier, but I was having too much fun. At this point the prop needed some cosmetic work and I wanted Sensenich to formally inspect the prop to baseline the actual pitch and recondition it. $750 dollars later the prop came back as a 74DM7-0-57 with a logbook entry and tag. It looked like a brand new prop.
Apparently there is significant drag in leading edge erosion and paint chips on the prop tips. The plane now has 25 hrs on the reconditioned prop. The plane has gained another 100 FPM in climb (1400) and a few more MPHs in cruise (117). If I hold the plane in my old 85 MPH initial climb it will exceed redline so a little more back pressure is needed to get the most out of the engine. This performance was in the heat of summer, so I'm hoping to get even more performance in cool air.
My question to those of you who have more experience - is this gain out of a reconditioned prop typical? I'm satisfied with this performance - I'd rather have the climb performance. Should I expect more? The factory work was quick, well done, and worth every bit of the cost knowing there isn't a hidden flaw in the prop. The performance gain was a bonus.
John
325 hours later the prop had provided great service. The plane climbed at 1300 FPM @ 85 MPH at 2700 RPM (solo) and cruised at 115 at 2450 RPM. I had planned to send the prop for service earlier, but I was having too much fun. At this point the prop needed some cosmetic work and I wanted Sensenich to formally inspect the prop to baseline the actual pitch and recondition it. $750 dollars later the prop came back as a 74DM7-0-57 with a logbook entry and tag. It looked like a brand new prop.
Apparently there is significant drag in leading edge erosion and paint chips on the prop tips. The plane now has 25 hrs on the reconditioned prop. The plane has gained another 100 FPM in climb (1400) and a few more MPHs in cruise (117). If I hold the plane in my old 85 MPH initial climb it will exceed redline so a little more back pressure is needed to get the most out of the engine. This performance was in the heat of summer, so I'm hoping to get even more performance in cool air.
My question to those of you who have more experience - is this gain out of a reconditioned prop typical? I'm satisfied with this performance - I'd rather have the climb performance. Should I expect more? The factory work was quick, well done, and worth every bit of the cost knowing there isn't a hidden flaw in the prop. The performance gain was a bonus.
John
