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Great Ozzie

Constant Speed Propellers

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Guest addonzealot

I was wondering if someone here could explain to me the proper way to operate an aircraft with a fixed pitch propeller. Do I use a low pith/highspeed at takeoff and a high pitch lower speed during cruise?What about during descent? During my use of certain aircraft in flight simulator I have maintained a low pitch propeller in hopes of ovoiding high manifold pressure and low propeller rpm. Now I strive for little more realism and wish for information on how to correctly operate such aircraft.Onboard the FSD Piper Seneca, my oil temperature stayed high through out the flight. Would leaving the propeller speed high cause this?

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Normal practice is to put the propellor in fine pitch for take-off and landing and in coarse pitch for cruise according the the a/c manual.


Gerry Howard

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From a maintenance perspective... alot of things can result in a high oil temp display but...Did u monitor the temps on the ground/thru-out the climb... and did u use cowl flaps during this time? Was the OAT above standard? Overly aggressive leaning might too but then u should see high CHT's/EGT's. Leaving the props full forward (as long as not past redline) would not be something I would suspect. In the Seminole, for example, the POH recommends using 75% power for climbing... cooling being one of the reasons for doing so. In my POH for Beech 58s/58As, 25 "square" (25 inHg. / 2500rpm) is recommended for normal cruise climb.It's been some times since I have flown a twin but if I remember correctly, mixture and props would go forward on descent and certainly verified when entering the pattern VFR or by the FAF inbound if IFR. Maybe someone else has better advice.Bottom line... check cowl flaps and ALWAYS follow the POH/AFM.Rob O.

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>It's been some times since I have flown a twin but if I>remember correctly, mixture and props would go forward on>descent and certainly verified when entering the pattern VFR>or by the FAF inbound if IFR. Maybe someone else has better>advice.>>Bottom line... check cowl flaps and ALWAYS follow the>POH/AFM.Something of interest, is that POH's might contain the words, full rich for landing or takeoff. While others might say, lean or richer as required.Yet, out here at 4600' msl to start with; we always lean right after engine start, and never go full rich on landing. If a go around was to occur, you'd have less power, than if leaned.However, we'll get pilots from coastal areas, who won't bother to lean for takeoff, because they're use to not bothering till 6000' or so of altitude back at their home flying area.But one thing is for certain. The difference between a leaned engine, and a full rich engine, is very noticeable at this altitude.As to props, it's a decision whether to go towards full forward during the descent for some additional braking effect, or just full forward on final, for the best power in case of a go-around. Items such as shock cooling and the prop forcefully spinning the engine also have to be taken into account.L.Adamson

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That is a good point about mixture, LAdamson. Actually, I would teach to lean mixture just after start and during taxi at our 900MSL airport (i guess i was paranoid about lead fouling... i remember vividly my frustration of cleaning the lead out of spark plugs). Of course I would lean above a certain altitude during enroute climb, but as per the AFM for the plane I was flying.In cases such as "out west" where the airport's field elevation is higher than the altitude we mid-western's use to go to the practice area... well I hope I drilled into my students' heads that they needed a short "mountain flying" course at the local FBO (well, anywhere they went actually, to get checked out locally to familiarize themselves with the area and local SOPs).My bet is if you check the POH for anything typed (type certificated) today under FAR23 (or even the older CAR3) there is going to be something in there about takeoff from "higher" density altitude airports and climbing enroute with respect to leaning procedures... especially if the manufacturer is still in business (one word in that case... liability). It's sad people don't take the time to know what is really in the manual. Like u said, people come out and have no clue about leaning because the only time they had to was with an instructor (I guess the attitude is, "why mess with it?"). But then again, every year people crash due to fuel exhaustion... what to do?My caution re: Always follow the POH/AFM... I would try to drill into my student

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