Manifold Pressure Gauge

[nightsta1ker]

We have two S300s. On one of them the MP gauge responds very quickly, almost instantly to changes in collective, and the other is very slow, sometimes taking up to 10 seconds to stabilize. Both of these ships have been like this for as long as I have flown them, and since I did all of my recent training (last two years) in the R22, I don't remember how the S300s I trained in back in '03 behaved. Honestly, compared to the way a 22 MP gauge behaves, both of these gauges on the S300s we operate seem funky. They do the job, and I have no reason to think that they are inaccurate, they just stabilize at very different rates.

 

Any insight?

[eagle5]

Maybe they just need a little WD40!

[Mikemv]

Have you discussed this with your maintenance provider or onsite A&P?

Edited June 30, 2012 by Mikemv

[Pohi]

No worries about the manifold pressure indication, just raise collective until you hear the rotor rpm droop and then you will know you are at max power. :-D

[nightsta1ker]

Mike, Yes to both. Everyone seems to think it is fine. But it has been bothering me for a long time.

Edited June 30, 2012 by nightsta1ker

[nightsta1ker]

No worries about the manifold pressure indication, just raise collective until you hear the rotor rpm droop and then you will know you are at max power. :-D

 

That only works if you have a governor. I know I am running out of power when my wrist starts to hurt!

[apiaguy]

Possibly an inline restriction from the #3 cylinder port to the gauge....

Maybe carbon deposit around the intake port blocking the line

Maybe hose deterioration leasing to constriction of the line while operating

Maybe the gauge bellows has issues

[nightsta1ker]

Thanks that gives me several places to start looking.

[zippiesdrainage]

Have you been feeding the Leprechaun under the cowling? Usually a delay in the MAP gauge is an early warning that they have been under fed lately (unicorn in the Schweizer).

[nightsta1ker]

Have you been feeding the Leprechaun under the cowling? Usually a delay in the MAP gauge is an early warning that they have been under fed lately (unicorn in the Schweizer).

 

Sure, I feed it. I feed it 15W 50 and 100LL.

[Btshanigan]

I know this is an old post but anyway...from my experience it is usually because the plug is too tight. I figured this out because we had a mechanic tighten one because that was his response to a fluctuating needle, which was actually a governor problem.

 

[nightsta1ker]

I know this is an old post but anyway...from my experience it is usually because the plug is too tight. I figured this out because we had a mechanic tighten one because that was his response to a fluctuating needle, which was actually a governor problem.

 

Thanks for the comment. It turned out to be a problem with the gauge itself, which was fixed by a repair facility. In any case, we no longer have that aircraft.