Full Power on Your Aircraft Engines

Aircraft under partial power

The Latest in “Stupid Ways” to Operate a Twin Cessna

The moon had to be aligned in some weird ways as we had two weeks of pilots who came in and were taking off with their 340 or 421C with partial power. Each of these pilots told us their “SUPER CFI – ONE OF THE TOP TWIN CESSNA INSTRUCTORS IN THE WORLD”, and one pilot who was supervised “BY A GUY THAT HAS BEEN DOING THIS FOR TWENTY YEARS”, were told to make 35 inch manifold pressure takeoff in a 340 and 421C. Honestly I really do not know what to say. This has to be the dumbest stuff I have ever heard of and the real problem is the pilots who believe this mess.

If you look at the Pilot’s Operating Handbook, on all models of Twin Cessna’s (and other aircraft), it says FULL THROTTLE for take off. This is just after making sure you have full RPM on the propellers. Yet even though Cessna and Continental have worked diligently in studying and preparing these Pilot Operating Handbooks to SAFELY operate these aircraft some people including instructors, have and are teaching “partial power” take offs. 

Years ago, and I mean years ago, I had a A&P tell me if an engine won’t run at full power for the sustained period listed in the manual, GET OUT OF THE AIRPLANE NOW. For instance, in the GTSIO-520, these engines will take full power over and over and over. They are designed for full power. What they are not designed for is partial power “straining” to swing the 90 inch props to get the load in the air. You are actually loading the engine and prop system with an overload. It is straining to do what it needs to do because some “person” (staying away from the word idiot) thinks they are saving the engine. Run the engine. Run the engine where it needs to be run. Don’t try to “save the engine” by underpowering a strong engine that is designed to run. 

Down powering an engine makes it run harder, dragging a load. If you were raised on a farm like I was then you will know that under powering a tractor engine pulling a load harms the engine. It is common sense. It strains the engine components in pulling the load you need to pull. The same goes for an aircraft engine.

Engines have to overcome “drag” thrust. Your engine is designed around the airframe to do what it is supposed to do with the maximum weight in the environment the engine is in. You are hurting the engine if you are straining the engine. Aircraft engines are actually designed to run more than maximum. That is why they have a takeoff rating and a METO rating. This is not hard. This only needs to be addressed with common sense.

Bottom line take off with full power and quit listening to these “know it all about airplanes gurus.”

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