200 rpm drop is outside the limits in the flight manual/ poh!!!
I would say the aircraft needs looking at asap, sounds like exhaust gases are leaking into the carb heat collector not just hot air, if this is the case you are putting exhaust gases back through the engine - not good
Get it looked at before it flies again.
JL.........
Last edited by JUST-local; 9th October 2007 at 20:05.
Reason: fight manual?