The International Cessna^® 170 Association

...if you ever operate any aircraft with a variable-pitch/constant-speed prop you might wish to know what the following, recently-issued FAA Information Bulletin advises:

P ponk has a site where you can determine the maximum you can turn a given diameter prop and expect to have efficiency. Most engines can stand some overspeed for a relatively long time. I was always taught to slow the airspeed down to maintain a given RPM and airspeed to mainintain level flight.

I agree, bluEldr, however this particular reference illustrates a peculiar anomaly of which some pilots may be unaware.... unless you slow down considerably...maybe even LESS than "best" or "recommended" glide speed... the prop may be at such fine pitch as to produce no thrust. The recommendation in such case is to slow the aircraft still further in order to overcome the peculiarity. (The condition described in the article reminds me of the theory-of-operation of the old Aeromatic props. Be sure to read the article completely in order to understand the concern.)

I find it incredibly ridiculous that a pilot flying an airplane with a constant speed speed prop would crash the plane only because the prop is set in the takeoff position. Unbelievable!

hilltop170 wrote:I find it incredibly ridiculous that a pilot flying an airplane with a constant speed speed prop would crash the plane only because the prop is set in the takeoff position. Unbelievable!

Richard's comment reminded me of how I felt after learning about the Air Florida 90 crash.... It was pretty difficult to imagine two pilots of any aircraft failing to advance full throttles when the stall warnings commenced.

In this case, I can only imagine that the person failed to corelate the rpm indications with the lack of thrust at regardless of glide speed.