sd330 sherpa very pt6a-45r illusive problem
Hello guys, let me start with a little background(obviously). Anyway I'm flying the shed for 4 years now. Some time last year (2014) was when i first experienced it. Here's what happened on the first occurence:
My right rpm dropped to around 900rpm then it stabilized right away. I was maybe in the final phase of takeoff. Then i requested for landing. Then right before touching down it did it again.
So the maintenance checked it but unable to find the cause(just assume that they did everything to try and troubleshoot the problem). So it was released for flight ( we have a term here in the Philippines.....it fixed itself up).
So after a few weeks of flying it it happenwd again but a bit longer than the first. Procedure dictates that i shut the engine down but, yes, it stabilized again so went on with the landing.
It was checked and still nothing seems to be causing it. Fcu, fuel nozzles, prop govs, overspeed , (accesory gearbox) all was checked but seems to be ok. Then one of our pilots met with another shed pilot and was told "oh that's normal, all we do is reduce the torque reset the prop and it'll be fine after".
So the maintenance released the plane for flight.
For 5-6 months now, it keeps doing it and i've come very accustomed to it (ye i know it's wrong, that's gen-av flying for us here). But this time it doesnt only happen during the initial phase of flight. It happens in cruise, descents and even during approach. BUT NEVER when the aircraft's on ground.
Earlier today something very different happened. It did a very little change in rpm but this time the fine pitch(ground fine/prop disc) illuminated. It did it 4 times but very little drop in rpm like it just coughed or something.
Here are the things that is being indicated when it happens:
Most of the time(3/4 of the time) the rpm drops then the torque increases but all other parameters stays the same (the fuel flow, ng, oil press, everything else stays the same).
But sometimes the rpm drops ahead of the torque but instead of increasing, the torque decreases as well and again the other readings stay the same.
And finally, in what happened earlier, the rpm dropped then the torque increased, all else stayed the same but this time the fine pitch illuminated.
So that's the case. So basically my question is any of you guys ever experienced this? Maybe on a king air or whatever thag has a pt6 engine?
Also the right hand has a newly overhauled props, just replaced the blades as well, new FCU, forgot the other stuff. And the engine still has 224hours remaining.
Hope you guys could ask around regarding my annoying problem.