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Ovation 3GX Manifold Pressure Indication Failure


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Fellow Mooniacs, looking for you’re help identifying this problem.  On prior occasion, the MP indication on my G1000 has gone erratic to the low side at higher altitudes.  Yesterday when flying at 10,500 in some very warm temps (high density altitude), the gauge became erratic again enroute to the SF Bay Area.  On my return flight, the gauge indication basically crapped out.  As I was l on final approach at my home airport, the MP began to read properly again, so lower throttle setting 10.5” MP, it was working.  On departure out of the Bay Area, it was working.  Again, conditions causing the malfunction are high altitude, or perhaps high pressure altitude.  Density altitude on my arrival was around 8,500’. This morning, when checking the MP in static conditions, it is now reading 23.7, which would be about right considering the current density altitude of 8,700,.   So engine running, MP indication errant and not functioning properly. High density altitude and hot ambient temps.  Engine running fine considering the hot weather.  Any thoughts on the source of the problem would be appreciated.  MSC says bad connection.  I think bad sensor.

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Did you get a new MP sensor with the G3X?

when the engine is not running… what were MP and altitude…. (Basic test of the MP system)

If you have an MP leak… the MP typical reads higher than actual…

A big leak and it will read the outside pressure at altitude.

It would be hard to produce power and get a low MP reading… other than a failed sensor…

PP thoughts only…

Best regards,

-a-

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MP indication gets screwy on occasion.  Just check the cannon plug and make sure it's clean and tight.  That fixes 99% of the problems.  I hope your sensor isn't bad, because I have learned that Mooney doesn't supply them anymore so it becomes a challenge to swap that out.

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Good news/bad news on this.  The MP line is fine, the fittings haven't moved and are not loose.  The canon jack plug appeared to be seated properly.  it was clean.  I am going to clean it anyway with contact cleaner and re-connect.  Haven't checked the wire harness connections to the plug yet, but they appear to be solid.  Looks like both transducers have never been touched since installation on the aircraft at time of manufacture.  there is no corrosion anywhere on the plug or sensor.

I have the part #, and that's where the bad news starts.

The part is no longer manufactured, and there is no replacement part.  it's a Kulite Air Pressure Transducer, p/n APT-20G-1000-25A

I am crossing my fingers that the contact cleaner will solve the issue, reconnect and I am on my way.  If not, we have a major problem.

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possibly good news…

You won’t be the first to have a Kulite sensor go awry…

A search around here should reveal what other people have done to find a different sensor…

Fortunately, the sensor isn’t a very unique device…

https://mooneyspace.com/search/?q=Kulite MP&updated_after=any&sortby=relevancy&search_and_or=and

Best regards,

-a-

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When I was wrestling with a balky MP again this spring, I told the A/P to clean out the plug but he also did some research on the transducer.  Apparently this came up in Beech-land as well, and they seem to have uncovered a solution he found on the web, but it was going to be pricey.  If Maxwell has an answer that would be good, and if you find this out please post to the group so we know.

Luckily for me, just cleaning the plug fixed it again. That's twice I've done this in  7 years of ownership.  I should just add it to the check-off list on the annual.

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I cleaned both sides of the plug today with electrical contact cleaner.  Reassembled.  Worked fine in static and run-up, but haven't flown it yet.

I am guessing that it is failing at high altitude and high ambient temps.

Interestingly enough, the MP was 24.4 static subsequent to cleaning, 23.7 prior to cleaning, altimeter 30.11 on both occasions.  Density altitude was 8,000' after cleaning.  The other day when it was 23.7, the DA was 8,700' with the same altimeter setting.

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