RPM Restrictions

[Newmooneyguy]

What is the reason for the prohibitive operating range in regard to propeller RPMs? I'm assuming it has something to do with vibration.

[OR75]

yes it does. even if you don't look at the rpm gage, you get reminded if you end up in that range.

[Chimpanzee]

However, you seem to have a three blade prop on there which has different ranges. I have a M20C and the prop on it is no longer the blade but a Hartzell three blade. If I understand the log entries correct, then I have to avoid only continuos ops in the specified range below 15 Inch MP and the initial restiction, eventhough stil coded on the tach is cancelled.

cheers

Norbert

[Hank]

I also have a Hartzell 3-blade on my C [bought it that way], and I avoid the 2000-2250 range redlined on the tach. I thought the face was redone when the prop was changed out? There is also the placard about "sustained operation below 15" MP" too.

[rbridges]

I don't see any placards for my prop. It's a "b" hub. Does that matter?

[Hank]

You don't have one of these? Ignore the Brittain stuff, see the little placard at the top, just below the tach.

I avoid it simply by not "operating continuously" below 15". A friend's F starts the gear buzzer below 15", and it doesn't stop when you push the throttle up--you've got to drop the gear; on my C, the gear horn squalls below 12", and politely stops when the throttle is advanced.

It's only part of the beauty and simplicity of the power-on descent.

[FloridaMan]

I know it's a bit off topic and related more to Hank's post, if you want to silence your gear warning and keep your power pulled back, finger your johnson's hole.

[jetdriven]

del

[1964-M20E]

OK so I understand it is vibration that is the reason for RPM restrictions but I have heard different numbers stated above 1950 - 2350. My old plane had 2100 to 2350 RPM my current plane has 2000 to 2350. Is it just the different prop models both are Hartzell? It seems that 2350 is pretty common but the lower number varies.

[Hank]

I know it's a bit off topic and related more to Hank's post, if you want to silence your gear warning and keep your power pulled back, finger your johnson's hole.

Oopsie, Antares . . .

[craigsteffen]

OK so I understand it is vibration that is the reason for RPM restrictions but I have heard different numbers stated above 1950 - 2350. My old plane had 2100 to 2350 RPM my current plane has 2000 to 2350. Is it just the different prop models both are Hartzell? It seems that 2350 is pretty common but the lower number varies.

Yeah, I'm curious about this too. The F model that I bought has a tach that originally had 2100-2350 marked in red, but then someone apparently colored in the 2000-2100 range in red also. I'll have to look in the paperwork to see what the official avoid range is.

[N201MKTurbo]

The vibration is tortional vibration it is the twisting of the crankshaft. You cannot feel it very much, but it is incredably stressful to the crankshaft and propeller. I have an article somewhere about the development of the R2600 crankshaft that goes into a great deal of detail on the subject. If anybody would like to read it let me know and I'll find it and post it.

[Stefanovm]

My 2009 Hartzell Top Prop manual and STC paperwork say NO 25/25 in bold. Guess upon what the seller insisted on my demo ride?

I printed the new prop's restrictions upon reading them and taped right below the tach. I ignore the old coloring and tried adding my own colored tape on the tach glass. Luckily it was almost a new prop (<10 hrs.), so hopefully not much damage from that OWT operation before I read the manual. The original, still there, tach markings do not come close to what the new prop paperwork lists as the restriction:

Yellow caution area is 2350 to 2550 above 24"

Red do not operate area is 25/25

Green normal operation area is 2100 to 2350 and 2550 to 2700

My engine seems to run the smoothest at 2100 to 2300 at low altitude and 2600 at altitudes where 65% is only available using the higher RPM

[Marauder]

I think the rpm limitations apply to the original Engine/prop configurations. In my 1975 F model, I have the F666-2 blades and have the 2100-2350 limitation to avoid continuous operation. I always thought if you changed out the prop to a 3 blade or different design, the limitations would either change or be eliminated. Correct?

[N201MKTurbo]

My insturment shop remarked the color bands on the face of the tach for $50.00.

[1964-M20E]

OK so I understand it is vibration that is the reason for RPM restrictions but I have heard different numbers stated above 1950 - 2350. My old plane had 2100 to 2350 RPM my current plane has 2000 to 2350. Is it just the different prop models both are Hartzell? It seems that 2350 is pretty common but the lower number varies.

I heard back from Hartzell and they said for my configuration and they said to avoid continuous operation between 2000 and 2350 which is what was on the placard. I’m still not sure why it would be so different on the lower number but until I hear something different that is it for my plane.

Prop Model: HC-C2YR-1BF

Blade: F7666A-2

Hub SN CH40600B

Blade SN D26023 / C94917

[Marauder]

I heard back from Hartzell and they said for my configuration and they said to avoid continuous operation between 2000 and 2350 which is what was on the placard. I’m still not sure why it would be so different on the lower number but until I hear something different that is it for my plane.

Prop Model: HC-C2YR-1BF

Blade: F7666A-2

Hub SN CH40600B

Blade SN D26023 / C94917

I do find it interesting that your range is a little different than mine. We should both be running the A1A engine. Wonder if there are other variants that affect the rpm limitations.

[1964-M20E]

Yes the IO-360 A1A engine. I'm at a loss for the different values as well. Hartzell was a bit short with their reply to my email.

[Kevin]

Ask me anything you want about this topic. I'm the guy who responded to John. What prop/engine/model Mooney do you have, Marauder?

[Marauder]

Ask me anything you want about this topic. I'm the guy who responded to John. What prop/engine/model Mooney do you have, Marauder?

I have the IO360-A1A with a two bladed Hartzell (F666-2) in/on a 1975 F. My prop limitation is for no continuous operation between 2100 and 2350. Why is mine different than someone who has the same engine and blade configuration but in an E model? Theirs is a continous operation limit of 2000 to 2350. Why the difference?

[1964-M20E]

Ask me anything you want about this topic. I'm the guy who responded to John. What prop/engine/model Mooney do you have, Marauder?

Kevin

Hi welcome on board. It is nice to have manufacturers lurking around to help with questions and theories.

[rbridges]

Ask me anything you want about this topic. I'm the guy who responded to John. What prop/engine/model Mooney do you have, Marauder?

my plane doesn't have a placard. Do some engine/prop combos NOT have an RPM restriction?

[Kevin]

It shouldn't be. You should have the same placard as John - no continuous operation between 2000-2350. Where are you getting the placard you claim to have? If it's from the Mooney POH or Operation Manual, I believe they changed that limit.

Just for the record, let's look it up ourselves, shall we? Follow this link: (from FAA Website)

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/45911b31a312cf79862576e8004c87c7/$FILE/P-920.pdf

This is the Type Certificate Data Sheet for the propeller. Go almost all the way to the end of the TCDS (page 8 of 13), and you will find a find a paragraph called "Note 9." This shows the propeller/engine combinations that are approved, and any placards that apply to that propeller/engine combination. These placards are applicable on your Mooney, Piper, homebuilt, golf cart, you name it. If those propellers are used on those engines, those limits apply.

Your prop will appear on page 9 of 13. You should be operating an HC-C2YK or HC-C2YK propeller with F7666(A)-2 blades. Find your prop model in the first column, then the blade in the second (note that the -2 is missing, but that's not important right now). Find your engine in the third column (it's the fourth set of engines from the top on page 9 of 13). Read the placard in column 6:

"Avoid continuous operation between 2000 and 2350 RPM."

That's all there is to it.

[1964-M20E]

Kevin

Thanks again. I guess my former plane had the wrong information.

One more thing I would think cruising for 30 minutes or longer would be considered continuous operation but is there a definition of what constitutes continuous operation?

[BigTex]

For whatever it's worth, my 1965 M20C is marked "No Continuous Operating in the Range 2000-2250 RPM". This is also what my Owners Manual states. I'm running a HC-C2YK-1BF Prop.