Whenever I run at high manifold pressure I get a kind of buzzing in the left engine. The sound repeats itself every few seconds and last a few seconds. But when I drop the MAP and the rpm's to cruise the sound either goes away totally (29.5-31.5 MAP) or becomes signifantly reduced in the 35-39 MAP range.What is this sound? I ask because yesterday I was in mid-flight when I wanted to climb a bit and I heard this sound, but then my engines crapped out on me and I had to restart in flight :). Thinking maybe this sound is a warning or something.

Oh-oh! Sounds like it's time for an engine rebuild! As Russ can tell you, having just gone through one replacement and one overhaul on BT, you are going to be eating beans for a while to afford it. ;-)My advice is never run above the METO (Maximum Except Take Off)RPM and manifold pressure settings on the engines. You'll find the numbers in the reference pages on the kneeboard.Be kind to those old mills! They don't come cheap! :-) Bill Rambow MAAM-SIM - Rambow, Visser, Banting, and Younghttp://www.fssupport.com/maam_sim/maamsim_logo.gif