RPM Guage markings

Ask Questions and Offer Advice Related to the Cessna 120 & 140 Type

Moderators: 6643, 6183, V529

Forum rules
You must be a member of the Cessna 120-140 Association in order to post new topics, reply to existing topics, or search for information on this forum. Use the "Join" link in the red menu bar.
Post Reply
User avatar
simonlowther
Posts: 50
Joined: Sat Mar 20, 2021 10:32 pm
Location: New Zealand
Name: Simon Lowther
Aircraft Type: C120
Occupation-Interests: Airline pilot Airbus 320
Contact:

RPM Guage markings

Post by simonlowther »

Hi all,

My 120 is fitted with a C85-12, it has a yellow range on the Tach at 2075 - 2300; I can not find any reference as to why this is present and what damage is risked operating in this range. Does anybody know what the story is with this.

Much thanks
Si
Simon Lowther

Cessna 120 (11102)
User avatar
6643
Posts: 2326
Joined: Tue May 01, 2018 7:00 am
Location: KLCI
Name: John C
Aircraft Type: 1946 C140/C90
Occupation-Interests: A&P, semi-retired
Contact:

Re: RPM Guage markings

Post by 6643 »

Back when the McCauley 1A90 props were first certified there was a restricted range and a required placard stating to avoid continuous operation in that range. In 1949 McCauley issued Service Bulletin 13 rescinding the restriction and calling for removal of the placard.
8342
Posts: 293
Joined: Sun Oct 14, 2018 11:55 pm
Location: KUSE Wauseon OH
Name: Rick F
Aircraft Type: C-140 (sold)
Occupation-Interests: Captain B-777 (Retired)
Contact:

Re: RPM Guage markings

Post by 8342 »

Does Cessna Service letter SLN-15 apply?

Rick
User avatar
6643
Posts: 2326
Joined: Tue May 01, 2018 7:00 am
Location: KLCI
Name: John C
Aircraft Type: 1946 C140/C90
Occupation-Interests: A&P, semi-retired
Contact:

Re: RPM Guage markings

Post by 6643 »

8342 wrote: Tue Apr 13, 2021 6:58 am Does Cessna Service letter SLN-15 apply?
I would have to say "No, not as of the issuance of McCauley service bulletin 13." Cessna was just passing on McCauley's installation information in SLN-15. Interesting there doesn't seem to be any updated bulletin from Cessna, though.
User avatar
simonlowther
Posts: 50
Joined: Sat Mar 20, 2021 10:32 pm
Location: New Zealand
Name: Simon Lowther
Aircraft Type: C120
Occupation-Interests: Airline pilot Airbus 320
Contact:

Re: RPM Guage markings

Post by simonlowther »

Great info, much thanks.

Si
Simon Lowther

Cessna 120 (11102)
User avatar
simonlowther
Posts: 50
Joined: Sat Mar 20, 2021 10:32 pm
Location: New Zealand
Name: Simon Lowther
Aircraft Type: C120
Occupation-Interests: Airline pilot Airbus 320
Contact:

Re: RPM Guage markings

Post by simonlowther »

Now found the SB in the resources section of the website. All good thanks.

Si.
Simon Lowther

Cessna 120 (11102)
a64pilot
Posts: 319
Joined: Sat Aug 29, 2020 8:41 pm
Name: Jody
Aircraft Type: C-140
Occupation-Interests: A&P former IA, Retired test pilot
Contact:

Re: RPM Guage markings

Post by a64pilot »

Don’t feel bad, for I guess the last 15 years or so that I’ve had the airplane, I’ve been staying out of the avoid range,I only learned it’s been rescinded the other day, now it’s ingrained as habit
Post Reply

Who is online

Users browsing this forum: Bing [Bot], Google [Bot] and 6 guests