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RPM Limitations

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RLCarter Grand Master

RLCarter

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In the process of redoing a few of the placards in my M20-E and researching to verify the correct wording but I cant seem to find one that is on the panel now. The one in question is printed on a clear label that a previous owner installed / or had installed, the first line reads “AVOID CONTINUOUS OPERATION BETWEEN 2000 AND 2350 RPM” which I have found and verified, the second line reads “ABOVE 2600 RPM IN FULL THROTTLE LEVEL FLIGHT”. I have looked everywhere I can think of and can’t seem to find anything referencing the second line of text “ABOVE 2600 RPM IN FULL THROTTLE LEVEL FLIGHT”. I have looked in the POH and the Type Certificate Data Sheets for Mooney M20E, Lycoming IO-360-A1A, Hartzell HC-C2YK-1B (Blades are 7666A-2), Airworthy Directives and Service Bulletins. I called a buddy that has a M20C and his does not have “ABOVE 2600 RPM IN FULL THROTTLE LEVEL FLIGHT”. I have also search here on MS with no luck, has anyone ever seen this and if so can you point me in the direction of the document that has it.

Info:
1965 M20E
Lycoming IO-360-A1A
HC-C2YK-1B

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RLCarter Grand Master

RLCarter

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7 minutes ago, PT20J said:

Required placards are listed in TCDS. 

Yes I know, but the plane currently has a placard that I can not find listed. I want to make sure it was placed there in error and not something I have overlooked 

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takair Grand Master

takair

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4 hours ago, RLCarter said:

not sure where they got the info from for the placard....i'm stumped too

I did some digging, but can’t even come up with a remote explanation.  2600 just doesn’t seem to tie into any particular requirement. The thinner green arc is 2500-2700.  All of the charts allow for a variety of combos.  

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carusoam Grand Master

carusoam

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I don’t recall that from my 65C days...

But Maybe... I Was following the OWTs of the day...  climbing out at 25/25... I never got anywhere near that stated limitation...

Follow up with your prop manufacturer... See if they have any limitations for the prop and engine combo...

I just checked the C POH... all the rpm limitations are described as painted on the tach...

thin green arc from 25-2700 rpm is in the rated category, recommended is the 23-2500 rpm range...

so it may be an interpretation of the recommended range?

Nothing found in The limitations section related to WOT or 2600rpm..

The phrase sounds oddly familiar, but not sure where it comes from...

PP thoughts only, not an engine expert...

Best regards,

-a-

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RLCarter Grand Master

RLCarter

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2 hours ago, pmccand said:

Actually, you can find an RPM limitation as an Airworthiness Limitations listed in the Hartzell Owners Manual ( page 19) on certain props used on A1A O360’s.  In short, RPM is limited to 2700 RPM for takeoff only, after which must be reduced to 2600 RPM for continuous operation. 

That is for the O-360 and the HC-C2YR-1BF/F7666A-2, I have an IO-360 and Hartzell HC-C2YK-1B/7666A-2

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Prior owner Experienced

Prior owner

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Possibilities from left field :P:

1) Prior owner had his teeth coming loose at 2600 because it needed a prop balance but he made a placard instead.

2) Prior owner discovered that tach was reading 100 rpm low so he made a bad placard.

3) Prior owner needed to remind himself to conserve on fuel.

4) Plane was in a partnership or flying club and someone didn’t want it flown at 2600 pm for some reason....

 

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Cody Stallings Experienced

Cody Stallings

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22 hours ago, carusoam said:

Want to see if MS’s prop guy is familiar with that 2600rpm, full throttle, level cruise limitation?  @Cody Stallings (Asking Cody now)

Best regards,

-a-

I haven’t seen any documentation on this.

My 67F Model has no placarded limitations on the upper end of the Tach.

I know both Engine an Prop are rated at 2700 rpms Continues.

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RLCarter Grand Master

RLCarter

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All the replies pretty much confirms my suspicion. Old placard has been replaced with one that now reads correct. The previous owner sometimes shows up at the QB meeting which is this coming Tuesday, I'll see if he remembers anything about it

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