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What should I have a competent A&P check?


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I put about 80 hours on 3RM before she went to Random A&P Referred by a Local M20J Guy. I've never had any issues starting her, I've never had a fouled plug, and I've always bounced off the rev limiter on take-off. Until now.

 

Now:

 

(1) Full rich at sea level, I make about 2640 rpm on initial climb-out. If I lean it, I can get it to 2700, but I shouldn't have to lean for best power on a sea level take-off, right? And I'd just as soon not touch the mixture control that early in the flight.

 

(2) The first run-up of the day, I always seem to have a rough running right mag, and Cyl 2 CHT drops to zero. If I run through the Mooney owner's manual fouled plug procedure, it cleans up. I lean aggressively for ground ops (to where the engine starts to sputter at idle, then increase to smooth, but just pulling the mixture back about 1/2 way used to be "good enough" and I never had any issues with mag checks before. (The A&P sent the mags to Aero Accessories for an IRAN.)

 

(3) The first start of the day is about like it's always been, but now it's incredibly hard to get started after it's sat for a bit - even like 2 hours on a cool day, oil temps having cooled below the green arc (EDM-830 and factory gauges). Tonight it took me dozens of tries over about 35 minutes before it finally caught, and even then it was like it was running at a very slow idle for like 15-20 seconds, before it finally settled into normal operation (throttle was at about 1500 rpm, and that's where it ended up). Once it was running and settled down, it was sewing machine smooth. I gave it a good twenty minutes at ~11-1200 RPM while I got my clearance, spun everything into the 430, briefed the departure, setup the NAV radios, verified the VORs, played Sudoku... Run-up was normal. Voltage was sitting around 12.1V consistently, dropping to about 10.x while cranking. When everything was running smooth, shop's voltage was 13.4 for a couple of minutes before settling at a normal 14.1V.

 

I have a mechanic looking at things next week; any ideas what I should have him pay extra attention to?

 

TIA!

 

 

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1) got any JPI data you can post?

2) Rough running on one mag is hint of what is happening.

3) Having a CHT go cold pretty much nails where something is going amiss...

4) Some homework on data collection you can do in advance...

  • what mags, how long since OH... sounds recent...
  • what plugs, how old... resistance check if they are Champion...

5) recent OH’d mags and ignition challenges and starting challenges that all have come up at the same time...?

  • timing often shifts quickly after OH and re installation requiring resetting the timing...
  • unlikely, but check anyway... loose mags can cause strange similar issues... re-using star washers when mounting mags is a known issue...

6) generally be up to speed on all things ignition related, while keeping your eyes open for other things...

Know that loose mags are not normal.  If you have one, you may have two very soon. A good sign of a loose mag... they wiggle a bit, and possibly leak some oil...

Start with posting some JPI graphs when able...

PP thoughts only, not a mechanic, just trying to help with the logic and possible homework you can get started with...

Best regards,

-a-

 

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6 hours ago, carusoam said:

1) got any JPI data you can post?

2) Rough running on one mag is hint of what is happening.

3) Having a CHT go cold pretty much nails where something is going amiss...

4) Some homework on data collection you can do in advance...

  • what mags, how long since OH... sounds recent...
  • what plugs, how old... resistance check if they are Champion...

5) recent OH’d mags and ignition challenges and starting challenges that all have come up at the same time...?

  • timing often shifts quickly after OH and re installation requiring resetting the timing...
  • unlikely, but check anyway... loose mags can cause strange similar issues... re-using star washers when mounting mags is a known issue...

6) generally be up to speed on all things ignition related, while keeping your eyes open for other things...

Know that loose mags are not normal.  If you have one, you may have two very soon. A good sign of a loose mag... they wiggle a bit, and possibly leak some oil...

Start with posting some JPI graphs when able...

PP thoughts only, not a mechanic, just trying to help with the logic and possible homework you can get started with...

Best regards,

-a-

 

JPI data mostly worthless (probable bad ground, being looked at by same A&P).

Bendix S4LN-200 mags, IRAN’d 21 hours ago (early November), everything else (plugs, p-leads, wires, harnesses, etc) replaced at the same time.

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Chris

Couple of thoughts.  The mag drop issue may be as simple as a bad plug.  Your mechanic should pull and check the appropriate plug.  They can tell a lot from its appearance.  

Regarding RPM, I have mine set just shy of 2700.  With warm oil...especially in summer, when it gets to temp faster....it runs closer to 2700.  In the winter it tends to run slightly slower.  Being a hydro mechanical machine, it is not always dead on.  The oil viscosity through the governor (a high pressure pump) seems to make a little difference.  What you want to pay attention to is trend.  Does it change behavior?  Does it drift over 2700?  Check to see if the max RPM is more related to oil temp than to leaning.  It may also change as oil hours go up or if you change oil viscosity.  Are you running the same oil as before?  I would not bump it up yet, as it sounds like the governor is generally limiting to 2700.  There is a chance you are over rich, but as I recall, this is at least your third servo.

regarding hot starts, a lot of things have changed on your engine.  I suspect you need to adapt to a new warm start procedure.  They seem to vary a little airframe to airframe (note the number of procedures that have been published).  

1.  Throttle 1/4”, mixture lean

2. Pump on

3. Mixture rich for 5 seconds (hot or warm start) and 10 seconds cold

4. Mixture lean

5. Hit starter.....when it fires slowly push mixture rich.....keep turning until solid start (couple of seconds)

6. Starter and pump off.

My results are consistent, but the prime time seems to vary between airframes.  There are other techniques on Mooneyspace that work as well.

Best of luck, have that plug looked at to be sure.  With the extensive work you had done, it may not hurt for your mechanic to do a good visual of the entire engine compartment.  

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Any chance during start up you or someone watching is getting a sight of black smoke from the exhaust? From what you are describing it sounds like you are too rich from base line of the fuel servo or an injector on the cylinder that is dead on start up is dripping. Just a thought.

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Check mag timing, Are you SOS? Where is the SOS point opening ? How about your SOS, working?  Are SOS wires secure? They have been known to loosen! plug condition, did someone drop one, a good ohm check! Check your mixture setting did the AP adjust your idle mixture, more than 50RPM rise could be an issue and to lean and you might find your engine lopping, , spitting and sputtering wanting more fuel when hot after landing taxing in.  look for air leaks along your intake, intake tube gasket condition, alignment, and  bolt torque(use torque wrench) 

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How,are you measuring RPM? Make sure you have an accurate assessment of what the engine is actually doing. 

Starting issue could be starter vibrator,  ignition switch or retard breaker. Take off EGTs should be in the 1150 to 1250 range for full rich take off. A fuel servo problem should be easy to see.  @Yetti the Bendix RSA Fuel servo cannot be set too rich, it’s not fuel flow adjustable other than with the mixture knob (idle mixture is the only mixture adjustment). It is either within spec or it’s malfunctioning.

You should not need to lean for take off unless DA and runway length necessitate doing so. 

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I didn't say it was field adjustable.  just saying it sounds like too much fuel.   But he has a new one on the plane, new fuel pump and lots of fuel issues.    Of course he also has new ignition harness and other lectronic bits.  So he probably needs a real mechanic to sort through all the things that have been changed.

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27 minutes ago, Yetti said:

I didn't say it was field adjustable.  just saying it sounds like too much fuel.   But he has a new one on the plane, new fuel pump and lots of fuel issues.    Of course he also has new ignition harness and other lectronic bits.  So he probably needs a real mechanic to sort through all the things that have been changed.

It’s not adjustable at all as far as I can tell. It’s either properly assembeld and calibrated or it isn’t. I have the Precision Airmotive maintenance training manual and I can find no provision for adjusting the full rich mixture. It’s a remarkably elegant design for mechanically delivering fuel.  One thing that can cause an overly rich mixture is a leak in the center body seal. That would allow unmetered fuel into the metered fuel chamber.

 

61929AD9-B126-4D1D-8F0B-2D9EFFA38140.thumb.jpeg.0971bc7afdad52e0249027a8f125a5ae.jpeg

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It’s not adjustable at all as far as I can tell. It’s either properly assembeld and calibrated or it isn’t. I have the Precision Airmotive maintenance training manual and I can find no provision for adjusting the full rich mixture. It’s a remarkably elegant design for mechanically delivering fuel.  One thing that can cause an overly rich mixture is a leak in the center body seal. That would allow unmetered fuel into the metered fuel chamber.
 
img][img]61929AD9-B126-4D1D-8F0B-2D9EFFA38140.thumb.jpeg.0971bc7afdad52e0249027a8f125a5ae.jpeg
If it was bad all cylinders would be rich and have issues if you only have one cylinder dead and comes alive after leaning and cleaning I'd look at injector

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10 minutes ago, Dream to fly said:

If it was bad all cylinders would be rich and have issues if you only have one cylinder dead and comes alive after leaning and cleaning I'd look at injector

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I wasn't speaking to the initially rough running mag but rather the speculation that the mixture is  too rich on take off. His dead "CHT"  (clearly he means EGT) could be a number of things.  It would seem to me the hard starting is more likely ignition related. I would start by inspecting all of the plugs and resistance testing them. While the plugs are out it would be very easy to verify the SOS and retard breaker providing spark at the correct timing.

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5 hours ago, Shadrach said:

I wasn't speaking to the initially rough running mag but rather the speculation that the mixture is  too rich on take off. His dead "CHT"  (clearly he means EGT) could be a number of things.  It would seem to me the hard starting is more likely ignition related. I would start by inspecting all of the plugs and resistance testing them. While the plugs are out it would be very easy to verify the SOS and retard breaker providing spark at the correct timing.

I was reading 2 + 2  = 6.   Rich on take off,  A flooded condition when starting and lots of recent fuel system work.   This is why with most systems only working on one part of the system at a time makes it easier to back track and find what is broke.   It's been quite the saga.  I would still verify ignition system then look at fuel system.  

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18 hours ago, Shadrach said:
His dead "CHT"  (clearly he means EGT) could be a number of things.  It would seem to me the hard starting is more likely ignition related. I would start by inspecting all of the plugs and resistance testing them. While the plugs are out it would be very easy to verify the SOS and retard breaker providing spark at the correct timing.


Looking at Savvy, you're right, it's EGT (doesn't drop to zero but drops off the readable range, down to about 365 when I was doing the fouled plug clear (down into the 1000 range during the preceding "regular" mag check). Plugs all checked out <25 hours ago, but I'll have him check the #2 again.

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1 hour ago, chrixxer said:


Looking at Savvy, you're right, it's EGT (doesn't drop to zero but drops off the readable range, down to about 365 when I was doing the fouled plug clear (down into the 1000 range during the preceding "regular" mag check). Plugs all checked out <25 hours ago, but I'll have him check the #2 again.

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Most any IA will now how to verify your starting and ignition system are both functioning properly.  I am going through the same thing. After decades of easy starting hot or cold,  things started to go pear shaped mid summer. Annual is due this month, so I pulled the mags a few weeks ago (which were due anyway (5XXhrsL and 11XXhrs right). They just came back from the IRAN and needed very little in the way of parts. I hope the problem is solved.

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On 11/22/2018 at 6:14 AM, takair said:

Chris

Couple of thoughts.  The mag drop issue may be as simple as a bad plug.  Your mechanic should pull and check the appropriate plug.  They can tell a lot from its appearance.  

Regarding RPM, I have mine set just shy of 2700.  With warm oil...especially in summer, when it gets to temp faster....it runs closer to 2700.  In the winter it tends to run slightly slower.  Being a hydro mechanical machine, it is not always dead on.  The oil viscosity through the governor (a high pressure pump) seems to make a little difference.  What you want to pay attention to is trend.  Does it change behavior?  Does it drift over 2700?  Check to see if the max RPM is more related to oil temp than to leaning.  It may also change as oil hours go up or if you change oil viscosity.  Are you running the same oil as before?  I would not bump it up yet, as it sounds like the governor is generally limiting to 2700.  There is a chance you are over rich, but as I recall, this is at least your third servo.

regarding hot starts, a lot of things have changed on your engine.  I suspect you need to adapt to a new warm start procedure.  They seem to vary a little airframe to airframe (note the number of procedures that have been published).  

1.  Throttle 1/4”, mixture lean

2. Pump on

3. Mixture rich for 5 seconds (hot or warm start) and 10 seconds cold

4. Mixture lean

5. Hit starter.....when it fires slowly push mixture rich.....keep turning until solid start (couple of seconds)

6. Starter and pump off.

My results are consistent, but the prime time seems to vary between airframes.  There are other techniques on Mooneyspace that work as well.

Best of luck, have that plug looked at to be sure.  With the extensive work you had done, it may not hurt for your mechanic to do a good visual of the entire engine compartment.  

All the plugs were inspected and replaced as necessary <25 hours ago (and it's been doing this since the first run-up I did when I picked the plane up; in fact I taxi'd it back, an A&P IA hopped in, and we cleared the fouling, I dropped him back off, went back out, did another run-up, and it was fine - he's the one who told me I wasn't "leaning aggressively enough," though again, the same procedure gave me almost 100 trouble-free hours before all of this work was done). Can't hurt to check them again I suppose but unlikely to be a plug, I think.

Re RPM: That makes sense. When I was observing higher RPM numbers, it was back in July, on hot days.  And I did switch from 20-50 to W100 with CamGuard.

That's basically the procedure I use when cold. My hot-start procedure (which never failed to get me going before) is the one that doesn't use the fuel pump at all, and just sits with an open throttle / mixture for 10-12 seconds. But, I have your procedure in my list o' procedures (I have like 10 different procedures in my ForeFlight checklist), and hasn't been working. :(

 

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1 hour ago, chrixxer said:

All the plugs were inspected and replaced as necessary <25 hours ago (and it's been doing this since the first run-up I did when I picked the plane up; in fact I taxi'd it back, an A&P IA hopped in, and we cleared the fouling, I dropped him back off, went back out, did another run-up, and it was fine - he's the one who told me I wasn't "leaning aggressively enough," though again, the same procedure gave me almost 100 trouble-free hours before all of this work was done). Can't hurt to check them again I suppose but unlikely to be a plug, I think.

Re RPM: That makes sense. When I was observing higher RPM numbers, it was back in July, on hot days.  And I did switch from 20-50 to W100 with CamGuard.

That's basically the procedure I use when cold. My hot-start procedure (which never failed to get me going before) is the one that doesn't use the fuel pump at all, and just sits with an open throttle / mixture for 10-12 seconds. But, I have your procedure in my list o' procedures (I have like 10 different procedures in my ForeFlight checklist), and hasn't been working. :(

 

Regarding the plugs, someone else mentioned it too, if they get dropped, they can behave strange, but seem to check out fine.  I think it has to do with the ceramic cracking and only revealing itself under heat and high pressure.  I made the mistake of installing a dropped plug as a starting mechanic and it behaved similar to your description...that said, it could be a other things too.  Simple way to sort it out is to move it and see if the issue follows.   

Regarding the start procedure, for hot start, I used to leave the boost pump off.  Once I started leaving it on, I noticed more consistent start.  I think it has to do with the fuel vaporizing in the heat.  Also, with those the hot start, I sometimes add more throttle if it does not catch within a couple of blades...I guess if I overprime.

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  • 4 weeks later...

Okay, the problem seems to be the #2 cylinder lower plug getting oil fouled when it sits overnight. Once that burns off, it runs fine. Not sure why it’s fouling (cylinders are ~300 hours old, all four were replaced in 2012). Also no idea why it only started doing this after all the attention at NTD/CMA. They should not have touched the cylinders...? At any rate, at least that part of the mystery is solved, and it doesn’t seem to be anything huge. If I have to replace a cylinder (worst case scenario?), that’s what, < $2,000? (Any good shops in SoCal?)

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Whats your oil consumption, if it's not excessive I'd wait on the cylinder replacement unless you have other indicators.

At the risk of starting a plug debate, I run UREM37BY exclusively in my IO360a1a - started when I began to have some oil fouling at startup - completely removed the problem

 https://www.aircraftspruce.com/catalog/eppages/temptestplugs8.php?gclid=EAIaIQobChMIrsWj4fir3wIVC0BpCh2F1wBXEAQYASABEgLgrfD_BwE

 

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Whats your oil consumption, if it's not excessive I'd wait on the cylinder replacement unless you have other indicators.
At the risk of starting a plug debate, I run UREM37BY exclusively in my IO360a1a - started when I began to have some oil fouling at startup - completely removed the problem
 https://www.aircraftspruce.com/catalog/eppages/temptestplugs8.php?gclid=EAIaIQobChMIrsWj4fir3wIVC0BpCh2F1wBXEAQYASABEgLgrfD_BwE
 


It's been just under 30 hours since the last change (I change at 50, or when oil gets noticeably dark) and I've added one quart. I've asked my mechanic about the Tempest plugs; the lower plugs right now are fine wire.


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One quart in 30 hours - I'm thinking that the plug isn't oil soaked unless the quart drop came in a short time - like in the last two hours of use.... if not I'm thinking more than likely just a bad/weak plug 

Edited by Mike Ropers
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One quart in 30 hours - I'm thinking that the plug isn't oil soaked unless the quart drop came in a short time - like in the last two hours of use.... if not I'm thinking more than likely just a bad/weak plug 

We swapped the plug to #4 and #2 had the same problem. Also, the plug was oil wet when removed...


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