Power setting table O-540-J1A5D

[Joe48]

Thanks Jeremy!
Do you have an email address of a specialist working for the engine manufacturer whom I could ask?

Joe

[aero101]

You can just google the manufacturer you want to speak to tech rep (Hartzell, McCauley, Lycoming, etc) for as telephone numbers of the tech reps are usually in contacts... Bottom line is bottom of green arch is the normal operating range from maule and you need to pretty much abide by that to be in compliance with their data.... When they do the vibration surveys on the props for certification the prop tips can and sometimes do move all over the place caused by harmonic vibrations from engine cranks, balance, etc, etc, etc.. If you stay in one of these harmonic ranges too long, your prop COULD break or separate a blade... And that would not be a pleasant experience, even if you did manage to survive it!!!

[Kirk]

The O540 J and IO540 W engines,
Normal operating range 2050 to 2400 rpm.
Do not exceed 23"MP below 2050 rpm as this a propeller vibratory stress limitation.

That's the bottom of the green arc since for certification the green arc is for 'unrestricted operation'. The only restriction below 2050 RPM is the 23" MP. The AFM, I believe says it's for propeller vibratory restriction. I am sure the McCauley behaves differently, but as Jeremy says, if it wasn't checked during the test flight the restriction may still be there even with the McCauley.

I don't run mine lower than 2000 RPM just because it really dogs along at that low setting and not that much quieter. But I see no problem doing it if you like it, as long as you are below 23" MP

Kirk

[aero101]

Kirk-
I agree fully with you as 20" and 2000rpm is a number I use quite often in a lot of airplanes to slow down, fly down wind at, etc, etc, etc... Some props do have vib restrictions at 1800-2000 and 2000-2200 ranges and you generally can feel that thats not a range the prop wants to run in anyway as they will shake... And as you say, I don't think anyone would want to constant cruz at those kind of numbers anyway as you're kind of just mushing along?

[Kirk]

2000 RPM is my favorite setting for 65%-55% and I run up to about 22" at that RPM. If I need more power I increase the RPM, then increase the MP. I can feel a vibration at the 23"/2000 seting.

That's always made me wonder about prop balancing. If Ihave the prop balanced at 200 RPM, might we be just moving the vibration range to some other unknown area?

Kirk

[a64pilot]

If Ihave the prop balanced at 200 RPM, might we be just moving the vibration range to some other unknown area?

Kirk

No, and I assume you mean 2000. The vibration ranges we are speaking of are a harmonic resonance range. Your not changing that without physically changing something in the prop like the CG of the blades, or stiffness, or length, etc. Everything has several natural frequencies at which excitation at that frequency will result in a vibration of ever increasing amplitudes. Think of the Tacoma narrows bridge for example. Avoid those frequencies, and you avoid the vibrations associated with them.
I think it would be one huge coincidence if two different props had the same avoid range. Many props have no avoid range, and some have more than one avoid range

[gear]

Found this in some paperwork that came with my plane. It is typed on Maule letterhead so I assume it is accurate.

M5 0-540-J1A5D, 235 HP

Power HP RPM MAP Fuel Flow (GPH)
100% 235 2400 27" 19.0
75% 176 2250 23" 14.5
65% 153 2100 21" 11.5
60% 141 2000 20" 11.0
55% 130 2000 19" 10.5

Note: Power setting and GPH are full rich mixture - sea level.

garth