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Rotax 447 can't get above 3,000' MSL

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10KFT

New Member
Joined
May 18, 2008
Messages
4
Location
Concord, NH
I'm now stuck with a 3,000' service ceiling. This problem has just recently developed. I need help because I usually fly at 3,500' - 8,500'.

If any of you have suggestions, please contact me at [email protected]. My Rotax 447 (with a 36mm Bing 54 carb and silenced intake) flew fine last summer, all winter, and into the spring. Now, I can't get above roughly 3,000' MSL without having the RPMs drop from 5600 down to 4000 and surge as the EGTs climb to 1200° - 1225°. The 3,000' is density altitude (i.e. if the density altitude at CON is 1,200', I can't get above 1,800' MSL...). I've checked the gas tank vent, fuel pump, fuel lines, etc. I've tried two different (new) carbs with 2.70/2.72 for needle jetting, 155/158 main jetting, 45 for idler jetting, and the e-clip in pos #2... nothing made a difference. I've broken the 3,000' ceiling only once, but then everything went back to the old problems. If I remain below my new "service ceiling" of 3,000', I can fly as long as I want with excellent engine performance and fuel consumption @ 4800-5200 rpm.

I do a top end overhaul every 150 hrs and Lockwood does a complete overhaul at 300 hrs. The engine was completely rebuilt 48 hrs ago and has run fine since the rebuild... until now. It has "failed" the last 10 test flights. Total time on this engine is only 348 hrs.
 
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