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Mooney bravo m20m edm indication


pkofman

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I started to hear a really high pitch noise and checked the edm 700.  This is what I see on the monitor.  # 4 is either not firing or something else. Engine is not really running rough and oil pressure seems perfect Anyone understand this. Sorry do not know why they load incorrectly why uploading   Peter

04513FC7-70E5-4D11-A9E6-B463F4CB3D0D.jpeg

6B395AA4-E937-4124-9E51-982311DDEFF7.jpeg

FBD120F2-033E-4E39-84C0-7E4D4C9EF5C3.jpeg

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I did not have a low-voltage alarm if you look at the CHT and Egt neither are showing correctly initially CYLINDER  four is blank. The plane just came off annual only about a week ago I don’t understand what’s going on with this is not normal for this plane so I won’t fly it until iunderstand it

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3 minutes ago, pkofman said:

I did not have a low-voltage alarm if you look at the CHT and Egt neither are showing correctly initially CYLINDER  four is blank. The plane just came off annual only about a week ago I don’t understand what’s going on with this is not normal for this plane so I won’t fly it until iunderstand it

How much power is there, low voltage and low egt makes me think low power. At idle my vopts are low and some egts dont even get above 1000 degrees so it doesnt show up on a bar. Did you do a runnup?

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This was different because I had no bar on number four and I heard kind of a high pitch sound it was different my voltage was not particularly low or lower than normal at low idle I’ve never seen that differential between the cylinders before 

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Did the squeal (high pitched sound) vary with RPM?

Do you download your JPI data regularly or do you have the download capability? If you have the capability, load your data up to Savvyanalysis.com.

Was there anything specific done during your annual out of the ordinary?

Just trying to get some more information to narrow down where to begin looking.

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18 minutes ago, Oldguy said:

Did the squeal (high pitched sound) vary with RPM?

Do you download your JPI data regularly or do you have the download capability? If you have the capability, load your data up to Savvyanalysis.com.

Was there anything specific done during your annual out of the ordinary?

Just trying to get some more information to narrow down where to begin looking.

See above

very high pitch noise did not really change with rpm  it was barely detectable unless you fly the plane allot   I noticed it  

I can’t download data 

I don’t think anything special was done during the annual and all compressions were normal   But @mooneydoc might have an idea 

 

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A couple of thoughts -

1. Could the squeal be coming from one of the alternator belts? Is it that kind of squeal or something else?
2. Just came out of annual - are the plugs torqued properly? Wouldn't be the first time spark plugs were only hand tight. It happens.
2. Are your pictures of the EDM at idle power? They appear to be. That could contribute to the 23.7V indication especially if a belt(s) is slipping.
3. Troubleshooting step for the EDM - select "Normalize" mode (LF depressed for 2 seconds) and confirm that #4 has a level indication with the other 5 cylinders for EGT and CHT. At least you'll get an idea of the status of the #4 sensors. If #4 data looks different than the rest when normalized I'd look at the sensor continuity and the secureness of the harness plug at the EDM as Lance suggested.
4. Do you see better performance from #4 and voltage closer to 28V at a higher power setting? Niko asked about doing a run-up - I have the same question. See #2 first though.
5. If everything else checks ok, a leaned higher power mag check, as lean as you can get it, may also give you an indication of an ignition system problem. Just watch the temps so as not to exceed limits.

From the mind of a man who looks for the simple thing first. Those are the things I would check.

Cheers,
Rick

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43 minutes ago, Junkman said:

A couple of thoughts -

1. Could the squeal be coming from one of the alternator belts? Is it that kind of squeal or something else?

no it was a very very frequency not like a car fan belt squeal 


2. Just came out of annual - are the plugs torqued properly? Wouldn't be the first time spark plugs were only hand tight. It happens.

 

dont know @mooneydoc might have better idea 


2. Are your pictures of the EDM at idle power? They appear to be. That could contribute to the 23.7V indication especially if a belt(s) is slipping.

these taken at idle just after a run up
3. Troubleshooting step for the EDM - select "Normalize" mode (LF depressed for 2 seconds) and confirm that #4 has a level indication with the other 5 cylinders for EGT and CHT. At least you'll get an idea of the status of the #4 sensors. If #4 data looks different than the rest when normalized I'd look at the sensor continuity and the secureness of the harness plug at the EDM as Lance suggested.

Ill try this
4. Do you see better performance from #4 and voltage closer to 28V at a higher power setting? Niko asked about doing a run-up - I have the same question. See #2 first though.

forgot to check the voltage during the run up but everything else checked out
5. If everything else checks ok, a leaned higher power mag check, as lean as you can get it, may also give you an indication of an ignition system problem. Just watch the temps so as not to exceed limits.

I  just had the mags done... maybe that is relevant or not.. Mag check on run up was within Poh limits or better

From the mind of a man who looks for the simple thing first. Those are the things I would check.

Cheers,
Rick

 

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9 minutes ago, pkofman said:

no it was a very very frequency not like a car fan belt squeal

Very high frequency squeal with low EGT and CHT at idle - possible induction leak on #4? I'm not sure how that would squeal though, now that I think about it, but it might? 

You've already got one of the finest on it if  @mooneydoc is engaged so I'll stop guessing now... :) Good luck, please let us know what you find.

Cheers,
Rick

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High pitched noise and a missing EGT sensor...

They may be related...

In an odd way...

Do you have a CO monitor on board?

I think if my EGT sensor got loose, it may start giving some bad data.... and my CO meter may start working in overdrive....

 

Can you swap two EGT sensors temporarily to see if the problem follows the sensor...?

PP thoughts only, not a mechanic...

Best regards,

-a-

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What is belt driven on the affected Bravo?

Only the spare alternator?

Only the primary alternator?

Does it sound like a belt squeal?   
 

Slipping belts have a capability to squeal...

 

 Makes you want to take the cowl off and see what may have come loose...

PP guesses only, not any PP logic involved... :)

Best regards,

-a-

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Last piece of logic I can get out of the pictures...

One pic shows the CHT #4 with its corresponding EGT... (a missing bar in the graph)

EGT#4 is the one asking for a check-up...  (the missing CHT bar doesn’t show when the graph has gone missing)

 

does the EGT wire go anywhere near a moving part?

Best regards,

-a-

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18 minutes ago, pkofman said:

I don’t know if the second alternator is belt driven or not. Someone here will  know. 
 

it was not a squeal or a sound like a lose fan best in a car.  Very very high frequency sort of sound 

Both alternators on the M20M are in front and are belt driven.

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Any updates, PK?

1) Seems like the pics of data are from a low MP setting...

2) the low MP is probably causing a few secondary issues like the low V....

3) Lots of interest in the high frequency sound....

4) Lots to expect with the low EGT on one cylinder...

  • Things that alter the compression like a leaky valve....
  • Leaky spark plug... CO and fire hazard...
  • fuel not burning in the cylinder, may show up in elevated TIT readings...
  • Of course... a loose EGT sensor will cause some low readings and possible odd sounds...

5) Nothing obviously connecting the squeal to the low EGT... unless the exhaust valve isn’t getting oil, and it’s Screamin’ for some... :)

6) If you want to get data downloaded out of the JPI... jpi  sells the various wires and plugs and converter to make it happen...

PP thoughts only...

Best regards,

-a-

 

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1 hour ago, carusoam said:

 

 

 

see below. thank you for checking in.

 

Any updates, PK?

No updates as I left town and cancelled my trip via the mooney so im not back until tomorrow but the shops are all pretty much closed until the 6th but we have  tons of bad weather and ice in the forecast for the coming days so the plane is going to sit in the hangar and im not flying it until I know that it is safe to fly.. I reviewed the manual sent earlier to me and it says it might be a light or compression but the compressions were all in the high 70's a week ago. Btw I had the magnetos o/h on this annual , I dont know if that could be the issue

1) Seems like the pics of data are from a low MP setting.

PK Yes except for one that I took right after a run up..

2) the low MP is probably causing a few secondary issues like the low V....

PK most likely ( they are going to check the alt's)

3) Lots of interest in the high frequency sound....

PK Me too. it was new and not mechanical in nature

4) Lots to expect with the low EGT on one cylinder... this is all very strange in that the annual did not show and of the issues below. Ive only flown 1 hour since annual @M20Doc may know better

 

Quote
  • Things that alter the compression like a leaky valve....
  • Leaky spark plug... CO and fire hazard...
  • fuel not burning in the cylinder, may show up in elevated TIT readings...
  • Of course... a loose EGT sensor will cause some low readings and possible odd sounds...

5) Nothing obviously connecting the squeal to the low EGT... unless the exhaust valve isn’t getting oil, and it’s Screamin’ for some... :)

 

6) If you want to get data downloaded out of the JPI... jpi  sells the various wires and plugs and converter to make it happen...

PK I dont get data from the jpi..

PP thoughts only...

PK Happy New Year to all and I will report back once I have some idea as to what is going on,.could not have happened at a worse time of year!!!!!!

Best regards,

 

Quote

-a-

 

 

Edited by pkofman
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So here is a little update.

Firstly   its the holidays ( everyone is back Monday ) so im hoping to get the  plane  to the shop to get the edm looked at , however Ive flown the plane a few times because the gauge is not required equipment ( a advisory only)  and although I have an odd indication on #4 ( reading  a delta of 350) below all of the other cylinders the plane is running and "runs-up" perfectly. everything seems normal. I also spoke to JPI. They said , get it checked  ( probably probes or a wire ) and if that is not the case it is a faulty  screen . 

I dont know much but I do know that if one cylinder was offline it would not sound good at all. Further I am developing about 36.8 in of MP at 0C and that is consistent with prior indications.So ill fly the plane to the shop and ill let everyone know what the tech guys find out.

Then there was the odd issue of the high pitch noise. It  turn out that it was the T&B  indictor gyro. Perhaps it was not enjoying the canadian cold  weather. Ill have to watch it but I was able to isolate it and pull the breaker and I could  start and stop this really super high pitch annoyance. It was just strange that it started at the same time as the edm700 went sideways.

 

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