RPM

by Frank Barker in 912 / 914 Technical Questions 5 years ago

Roger,
Installed a new 912 ULS, (now 100 Hrs.) I’ve been told,or read somewhere, the engine should be operated not less then 5000 RPM for effency and longevity. In fact 5500 ALL DAY or considered a realistic MAX Continuous. Comment? FB

Re: RPM

by Roger Lee » 5 years ago

Roger Lee

127 5.21k 4.79k

You really should do the majority of your cruise time above 5K. Most these days seem to be in the 5k - 5.3K rpm range. This is for fixed pitch and ground adjustable props. I wish we all could use CS props. Yes it can run at 5.5K all day. Save the 4K range for pattern work and circling something you want to look at.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: RPM

by Douglas Engel » 5 years ago

Douglas Engel

2 6 0

Why isn’t this in the operator manual? I have been cruising around all day at 3800 to 4200 rpm. This is not recommended? Am I damaging my 912 uls?

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Re: RPM

by Garrett Wysocki » 5 years ago

Garrett Wysocki

1 572 1.45k

The intake manifolds are tuned for smooth operation between 5000 and 5500 rpm cruising below that will increase vibration damaging/wearing the gear box components including increased wear on engine mounts, exhaust system, wiring harness and air frame components that are susceptible to vibration related wear and tear. If you are new to Rotax there are classes available around the USA that I would highly recommend that teach how it operates in detail and what and what not to do to ensure your motor makes it to TBO.

Thank you said by: Douglas Engel

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Re: RPM

by john gunn » 4 years ago

john gunn

4 29 221

Holas & howdies, im surprised their isnt a bit more discussion on this, Like Doug, i normally fly my s-lsa "e-fox" 912uls at 3750-4250 and it purrs like a cat. In fact the only time i push 5k is on t/off ! I find there to be less vibration & certainly alot less noise (DUC swirl prop). Oil & CHT temps are lower too, typically 145-165 depending on ambient. Lastly, it seems to sip ~ 25% less fuel/hr in that mode ?

25142_2_IMG_0715.JPG (You do not have access to download this file.)

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RPM

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