Teller1900
En-Route
We have a FBO (AvaintAir) full of those P-180's. They are noisey on the ground and you can hear them on a 4 mile final. A friend works on them, he tells me stories of carbon build up on the props and replacing the door seals for pressure is common.
I am VERY well familiar with that FBO! Your friend is correct. They are exceptionally loud on the outside; yet it is THE quietest plane I have ever flown, on the inside (and one of the quietest I've ever ridden in).
The carbon build up on the props is due to the fact that the props are only about 6 inches behind the exhaust stacks. We used to have to clean them ourselves at the end of every flight day. Fortunately that's a maintenance only problem now! On the other hand, the benefit of having the props there is that we don't have to have prop heaters, or any other form of prop deice - the exhaust does it for us. One less thing to break! (The only way the exhaust isn't going to deice the props is if the engine is shut down. In which case, we probably have bigger issues).
Ahhh the door seals. Gotta love the door seals. This plane is just like the 1900 in that way. On the Piaggio, it's because they did the two part door (top half swings forward, bottom half drops down and becomes stairs) instead of going with the Citation design of a single forward-swinging door and a separate fold-down stair. The seal is USUALLY fine around the outside, it's the horizontal joint where the two halves overlap that is the recurring problem. That, and a really stupid nose steering design...