Red zone for RPM's?

[Moonbat]

2 hours ago, takair said:

I’m curious. Where were you able to find the counterbalance type for your A1A?. I had thought they cut in with the A1B6. I’m very possibly looking for the wrong thing. 

I am going to retract that statement until further notice. I looked back into where I saw that, and it was the (mostly) unreliable Wikipedia. Sorry. I'll keep digging. 

[Ragsf15e]

6 hours ago, EricJ said:

The STC for the new prop would be more correct since it is supplementary to the TCDS.   I'm in the same boat, as my JPI is marked per the TCDS but the STC for my Hartzell Top Prop carries no yellow arc limitations.   I can still feel that the vibration is different in the yellow arc, so I try to minimize time spent there.

Thanks that makes sense.  I guess I assumed the yellow zone was for the engine, not the prop, but that’s what I get for assuming.

[Guest]

I thought that the A1A engine has no floating crankshaft counter weights?  From the IPC item 15 is the counter weight.

Clarence

[M20F-1968]

The A1A is not a counterweighted engine. 

John Breda

[markgrue]

On 3/11/2020 at 2:16 PM, carusoam said:

When looking for the rest of the hot prop parts...

There should be a ring mounted on the front of the engine...

And something connected to the shaft or prop that runs against the ring...

This would be the important system required to transfer electricity to a spinning prop.

Best regards,

-a-

Just to clarify...  The ring is mounted on the prop spinner backing plate and there is a brush assembly on the front of the engine.   Any engine with counterweights will have  a number in the 4th position of the engine number suffix.  The number will denote the type of counterweight.  They will be different for different props.  

 

Mark

[carusoam]

Thanks for the details Mark!

I couldn’t think up a third of the details while writing the post.

The brush assembly was visible for one prop I had a slight memory of... 

Best regards,

-a-

[PT20J]

Per attached:

Counterweight Applications:  On 4 cylinder models – the #6 as the 4th suffix character indicates one sixth and one eighth order counterweights.

SSP-110-1 Certificated Engines.pdf

Skip

[Bruce E]

Answers for red zone limitations, for stock configurations are in the TSDS. Type Certificate Data Sheets. If you have a non stock configuration the answer will be in the STC for that installation. TSDS have both model specific from the beginning and end with applicable to all. 

[M20F-1968]

On 3/10/2020 at 12:28 PM, Moonbat said:

The JPI EDM930 in my plane came with the settings between 2100 and 2350 RPM designated in RED. So I have studiously avoided continuous operation in that range. The plane has a turbo-normalized IO360-A1A engine and an MT-Prop (3 blade). Before I owned this plane, it had two different Hartzell 2-bladed props on it (no - not at the same time!), and, of course, at one time it was not turbo-normalized. I have read all the STC's related to my equipment, and find only that the current MT-PROP has a limit: No continuous operation above 2700 RPM. I see in the older Hartzell prop STC's, there are limits on ranges similar to the 2100-2350 range that is marked in RED on the JPI digital tachometer. 

There is also a "Power Plant Limitation" noted in the original POA. On page 45, it says "No Continuous Operation in this Range": 2100-2350. This is the likely reason for the "Red Arc-Wide" limitation on continuous operation between 2100-2350 RPM. 

Does anyone know the "why" of that limitation? 

(I am aware that most props on planes like this run more efficiently at around 2400. Efficiency is not what I am asking about. I am asking if there is some other reason that the 2100 - 2350 RPM zone might be RED. I've never noticed any vibration in that zone as I transition through it.) 

I would also be careful running your MT Prop with a Turbo-normalized IO-360A1A.  I have a 1968 F model and looked into using an MT Prop with a Turbo-normalizer.  Both STC's allow for use with the original Hartzell propeller that came with the IO-360A1A.  A Propulsion DER stated to me that if I used the MT prop I would need to prove to the FAA that there is no incompatibility between the MT prop. on the turbo-normalized engine.  

You may safe, you may be unsafe, you may be illegal, and you are a test pilot.

John Breda

[Pinecone]

Red/yellow zones are for the engine and prop combination.

Change the prop and the zone may move or go away.   

The also exist with fixed pitch props.  The Grumman/Gulstream Tiger (O-360-A4K) had a yellow zone on the early ones.  There was an STC to change to a Sensenich prop and you lost the yellow zone for RPM.  And also gained some 8 - 10 knots cruise speed.