My Adventurer is equipped with a 3 blade Ivoprop Medium in flight adjustable prop, and the thing is becoming the bane of my flying existence. I have had dramas with it ever since I got it, and I would be interested to know if anyone else has had these issues.
Firstly, after I brought the prop I discovered that there is a requirement to re-torque the mount bolts every 10 hours, and inspect movement strips before very flight. Not a biggie but additional maintenance that I hadnt considered initially. Fortunately I have a Maintenance approval for this aircraft, otherwise NZ regs say a LAME has to do the retorquing - which would be pretty expensive after a while.
I'm also really disappointed with the design philosophy, which is frankly agricultural. You know when the prop reaches its travel stops because the circuit breaker pops. You then wait a few seconds, reset it and carry on - standard operating practice! No limit switches or anything like that... The bare ends of the wires from the pitch change motor just slip in between nylon washers as you assemble the prop - no terminations etc. If you put the blades on 30 degrees out of index the wires get pinched by the pitch change cams - no warnings or notes to this effect in any of the brief assembly documentation. Whilst the aircraft was sitting for several months the factory grease in the pitch change motor's planetary gearbox turned into something like hardened chewing gum - I couldnt get the RPM I required as the CB kept popping, indicating full travel, but in reality popping because the motor wouldnt move! I had to totally pull the gearbox apart and regrease with Aviation grade grease. The requirement for re-torquing probably comes from the use of soft nylon as insulating spacers in the hub assembly - over time it compresses which changes the bolt torque loading - at the same time the material gets squeezed out between the contact rings, and the odd frayed end will destroy the contact blocks... Its happened several times to me.
I've done several 100hr inspections now, which generally dont require anything much on the prop other than the normal re-torque and cleaning bugs off the blades, but each time now I have found the pitch change not working when I do the post inspection runs. I'll have to pull the prop apart this weekend to find the latest issue... I'm getting real good at that now!
If I had known the Ivoprop was so troublesome I would have tried an alternative, Although there arent many suitable options in this instance. I really need the variable pitch to get decent takeoff performance without overspeeding the geared engine in the cruise (I'm running a 140hp geared Subaru) and the locally built Airmaster is only rated for 100hp max. any changes now would mean huge changes to the cowling and possibly gearbox config, so I'm stuck with it for now. To be fair, when it is working it is a great unit and certainly behaves well, I just don't know when it will decide to misbehave again. Is it me, or are these props normally this crap?