Originally Posted by
deadstick35
per side, right? Didn't you do trend monitoring ,too, for higher TBO's?
Yep, per side. Like I said, though, at 26" and 75 ROP it's more like 14gph when you're at 8 or 9000ft density altitude- the Chieftain will indicate 150 and true out at about 170. Bump it up to 30" and your burn increases to the 18gph, indicated and true increase about 10kts, and time over 200nm is about six minutes more. Blocking out 10 minutes early saves more time than you could ever recover in flight on a medium-length trip.
Yes, we trend-monitor on revenue flights- I don't know of any runs that lack a leg more than 30 minutes. I'm not sure if it's specifically for TBOs, but to keep an eye on stuff to prevent surprises. Theoretically.
Historically, AMF has had very good results with leaning to 75 ROP. Cylinder head temps usually stay under 400, oil temps under 200, so the engine isn't being cooked, and very seldom do the plugs get fouled. I would imagine running higher MPs at 75 ROP might cause problems, though.