M20J not producing thrust

[Sfurr201]

I recently bought a 77 J model that will not true out any better than 138kts. I didn't buy a mooney to do 138kts. I don't think it's rigging, the plane tracks and trims out great and everything seems to close up nicely, yes I put it on jacks and checked the gear. The engine has a little over 800hrs on it and all pistons are above 70. The prop is a hartzell schimitar with 250hrs on it. During a static run we could barely reach 2400rpm. We adjusted the prop to reach 2700 but made no difference in cruise.  We cleaned gapped and rotated the spark plugs, also had a small intake manifold leak fixed but all in all everything looks really nice. The engine starts well and runs smooth. Can anyone help account for the loss of rpm and nearly 25kts slower cruise speed? Could it possibly be a problem with the prop which I doubt? I am outside of Charlotte NC can anyone recommend a good engine shop near by?

[Mr Bill]

Sfurr,  If you need help for troubleshooting, Race City Aviation at 14A. If you need serious engine work, Triad in Burlington, NC is another option.

Bill

[eman1200]

Hi sfurr, I also can't answer your question, but am located near JQF, if you were ever looking for local peeps to fly somewhere with.

[LANCECASPER]

23 minutes ago, Sfurr201 said:

I recently bought a 77 J model that will not true out any better than 138kts. I didn't buy a mooney to do 138kts. I don't think it's rigging, the plane tracks and trims out great and everything seems to close up nicely, yes I put it on jacks and checked the gear. The engine has a little over 800hrs on it and all pistons are above 70. The prop is a hartzell schimitar with 250hrs on it. During a static run we could barely reach 2400rpm. We adjusted the prop to reach 2700 but made no difference in cruise.  We cleaned gapped and rotated the spark plugs, also had a small intake manifold leak fixed but all in all everything looks really nice. The engine starts well and runs smooth. Can anyone help account for the loss of rpm and nearly 25kts slower cruise speed? Could it possibly be a problem with the prop which I doubt? I am outside of Charlotte NC can anyone recommend a good engine shop near by?

It looks like the previous owner was in Texas, who did your pre-buy?

 

I would get it to a respected Mooney Service Center and have them look at it.

[Bob - S50]

Two things I would check, one of which was already suggested.

1.  Magneto timing.

2.  Accuracy of your airspeed indicator.  Ours was off by as much as 8 kias.

[Bob_Belville]

Do you have an engine analyzer?

You don't mention MAP. Are you getting within an inch of atmospheric pressure at take off?

Do you have a FF indicator? You should see 18 GPH on take off.

You're 1/2 hour from KMRN - Foothills Regional Airport - where I am and more importantly where AGL Aviation Services, the only Mooney Service Center in the Carolina is. Bring it here and Lynn will figure out what's going on. 

[Bob_Belville]

The need to change the prop governor from 2400 to 2700 is troubling. Who is helping you? There's nothing unique to Mooney in that IO360/governor/Hartzell Scimitar prop combo. 

[Sfurr201]

Thank you for all the replies and suggestions. I will do my best to answer them all. I have not checked the timing yet, I am getting 30man pressure at take off but who knows if the gauge is correct. I do not have a FF but do have a JPI 700, #3 which is new runs a good bit cooler but everything seems good. I will probably have to get her out to the mooney service guys at foothills

[Bob_Belville]

13 minutes ago, Sfurr201 said:

Thank you for all the replies and suggestions. I will do my best to answer them all. I have not checked the timing yet, I am getting 30man pressure at take off but who knows if the gauge is correct. I do not have a FF but do have a JPI 700, #3 which is new runs a good bit cooler but everything seems good. I will probably have to get her out to the mooney service guys at foothills

30" sounds a little too good for Charlotte at about 600 MSL. I'd expect 29". If you haven't done so, take note of the MAP gauge before starting the engine. On a standard 29.92 day in the Charlotte area I'd expect it to show about 29.5 or a little less. If it does the gauge is probably okay. OTOH, if on take off you're only seeing 27" or something like that you might want to inspect the air filter or even the muffler for partial blockages. Ideally with the throttle wide open you want the engine to get as much air as possible. 

Not sure about the J but for a lot of us, me included, #3 cyl is most often the hottest. But I think that incidental to a bigger problem.

[carusoam]

Welcome aboard,

There is a lot missing in your statements.  You have just joined MS after buying a Mooney?  

Expect to get some help, but it might not sound very friendly at first.  We are avid Mooney pilots first, and not always the best writers...

Sounds like a good time to start with a review of everything.  Make a list of what is working. And what is not...

1) Starting with how are you measuring the speed, and what are your expectations?  Most Mooney pilots discuss speed in terms of KTAS at a given altitude and power setting.  Then they use a three way course and a GPS driven ground speed to determine how well the ASI is actually working.

2) Next steps are with the instruments. When they are forty years old, they may no longer be in calibration.

MP, RPM, and FF...  These are the devices that will let you know if the engine is OK to fly behind.

300 rpm slow is greater than 10% of available HP and equates to a very long T/O run and slow rate of climb.

Around  once each year a new Mooney owner comes aboard after buying a plane without much of a PPI.  They took on the risk that everything might work out well.  Sometimes they find some metal in their oil filter during the oil change. Power is directly related to cam performance. If the cam is failing, the power will be off...

The rpm being this far off is not a normal thing. Use an iPhone app to obtain what the rpm really is for comparison.  Is the low rpm something new after purchase?  (A low time pilot with a check list would have found this on a test ride)  the prop's governor can make the engine look bad.  Setting the governor properly is a simple mechanic's job. Rpm indicators can be off by 50 rpm, not 300.

3) Feelings about how well a plane is rigged will be very misleading.  Proper rigging requires tools and procedures.  A mechanic can balance a plane to fly straight. It will feel right it will also be slower than a properly rigged aircraft.

4) Did you really buy a plane without a pre purchase inspection, PPI?

5) expect taking a Mooney to a qualified shop to check on things can be very expensive.  Do as much as you can yourself before dropping a plane off and asking them to look at everything...

I hope this is helpful.  I'm only a Private Pilot with crummy writing skills...

Best regards,

-a-

Edited January 21, 2017 by carusoam

[bonal]

Welcome to MS like many I am full of opinions and don't have any grounds based on real professional experience. That being said my question would be what are you basing your TAS on. My recommendation would be as Carusoam suggested do a 3 or 4 heading gps speed track and check results. Might be as simple as an inaccurate AI. Good luck with the search and please let us know what is discovered. Also I always like to see pics of another Mooney.

[Sfurr201]

The rpm was a little low when we picked it up but I quickly built up on the ground roll, it seems to have gotten worse. I'm sure the gauges and little things like that need calibration. This is my 8th airplane through the same broker and he has agreed to eat some of the cost on this one. The airspeed indicator is accurate. I don't believe I need a certified mooney shop as much as an engine specialist. I just want to plane close to book speed I have to wild speculations. I typically could care less about true airspeed and 3 or 4 knots here but 20 or so knots I care about. 

[lukejb]

I have a 77' J.  It flys straight and TAS has always been closer to 150kts TAS at 8,500 at 75% power.   A little faster if I am lightly loaded. What altitude were you flying at for the 138kts TAS?

Edited January 21, 2017 by lukejb

[Bartman]

My 2 cents based on 10 years experience with Mooney Space and a 40 year old M20J, but you also have lots of experience taking care of 8 aircraft.

RPM      These gauges are 40 years old and mine is off a little bit too.  I think it less likely that you gained 300 RPM going down the runway, and more likely the RPM gauge "warmed up" and increased. I would be much more interested in the before and after recorded by the mechanic who set the governor. 

ASI        Mine is 40 years old and reads about 10 Kts slow.  In smooth air at optimal settings and altitude I can do 158 ROP but prefer 150 LOP.  Apples and oranges.  This is based on 3 and  4 way GPS average calculations not the ASI.

As others who are much more knowledgeable than me wrote above, in addition to confirming RPM I would confirm the fuel flow, and ignition system including mags and timing, wires, and consider the plugs.  Some swear by fine wire, some think it is voodoo and almost all agree Campion sux.

Lastly, I personally think there is both a Mooney Factory variation, and Mooney Space speed correction factor for speed and many other issues.  Being hand built some birds are faster, but speed depends on many other factors such as speed mods, flap elevator and gear rigging, weight and balance, LOP vs ROP, density altitude and many others.

Good luck, keep us posted, and WELCOME to Mooney Space !

 

[MB65E]

Hi Welcome!!! You are in the right spot!! Great people here, and we all want to help!

I would see when the mags were last overhauled. Also, check the ohm reading on the plugs. I bet you have some over 5k. See what timing stamp your engine data plate has. Calibrate the rpm with an electronic eye. Use that vs your factory tach. 

Check for blockage in your finger screen on your fuel servo. Some have never been opened up. Lack of maintenance. 

Post pictures of your flaps and ailerons. Most cases the flaps and ailerons fair in together. I have my flaps and ailerons rigged up as much as allowable. Ailerons more than the flaps. If your flaps are faired with the ailerons, maybe both are drooping too much. 

Check for Loose gear doors, poor engine baffling.

Finally, have your tech pull the valve covers, and measure the rocker arm travels when the engine is pulled thru. The slightest difference could mean your cam might be going flat. 

Hope this helps!! 

Good luck!!

-Matt

 

[gsxrpilot]

IF you have an engine problem, then any engine guy will do... and any owner forum will do as well.  But if it's not exclusively an engine issue, (and it could be any one of a million other things,) you're gonna need a Mooney specialist.

Don Maxwell got my first C to do an additional 10 knots TAS after he straightened it out. Someone who was an expert at rigging Cessna's had rigged it all wrong.

[Guitarmaster]

x2 on the rigging. +9 KTAS After rigging properly.
The Mooney is super sensitive to rigging. The slightest misrig will be big numbers in terms of TAS.

Sent from my XT1585 using Tapatalk

[cnoe]

I'm curious about all the "rigging" talk. I have no complaints about my J's average speed; 150-160 kts depending on settings. But if I could gain 3-4 knots by simply raising the ailerons a couple degrees then why not. Still I understand that the earlier models (mine's a '78) aren't as fast as the newer ones so I may not gain that much. I'm not spending money on the one-piece belly etc. Again, 150 KTAS at 9.0 gph is fine, but if there's some "free speed" I'm missing out on then please speak up.


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[Sfurr201]

The man that calibrated the airspeed  is a 22,000 hr pilot with American Airlines (no not a typo) he also flys most every bird in the sky including war birds and my company's Aerostar 600. I would never be able to own the planes I have without his knowledge and help. That being said we missed something when we picked up this bird. I will post pictures soon. She is beautiful and I couldn't be happier with how the controls feel. All controls seem to line up well. Now this particular plane is actually lighter than from the factory but has a forward CG (with two people up front it's close to forward limits) could that make that much of a difference as I know an aft CG is faster

[gsxrpilot]

6 minutes ago, Sfurr201 said:

The man that calibrated the airspeed  is a 22,000 hr pilot with American Airlines (no not a typo) he also flys most every bird in the sky including war birds and my company's Aerostar 600. I would never be able to own the planes I have without his knowledge and help. That being said we missed something when we picked up this bird. I will post pictures soon. She is beautiful and I couldn't be happier with how the controls feel. All controls seem to line up well. Now this particular plane is actually lighter than from the factory but has a forward CG (with two people up front it's close to forward limits) could that make that much of a difference as I know an aft CG is faster

No offense, but nothing here says anything about his expertise with Mooney's. There are lots of experts in a lot of things. And seriously 20,000+ airline pilots are a dime a dozen. But there is a reason that people fly their Mooney's all the way across the country to be touched by Don Maxwell at KGGG or Paul Loewen at 1O2.

The guy who taught me to fly, was and still is my mentor for all things aviation, is a 52,000 hour 747 Captain from PanAm and Braniff. 16,000+ hours as a CFI in the right seat of various Pipers. He did my Mooney check out when I bought my first (700 hours in Mooney's). He knows more about airplanes than anyone I know. But I wouldn't let him evaluate the rigging on my Mooney even if it was free.

[gsxrpilot]

32 minutes ago, cnoe said:

I'm curious about all the "rigging" talk. I have no complaints about my J's average speed; 150-160 kts depending on settings. But if I could gain 3-4 knots by simply raising the ailerons a couple degrees then why not. Still I understand that the earlier models (mine's a '78) aren't as fast as the newer ones so I may not gain that much. I'm not spending money on the one-piece belly etc. Again, 150 KTAS at 9.0 gph is fine, but if there's some "free speed" I'm missing out on then please speak up.

Probably no "free speed", but if your J was grossly out of rig, a proper rigging would certainly allow it to go faster.  My first C was way out. There were various tabs riveted to ailerons and such. DMax corrected it all and found quite a bit of speed hidden by the poor rigging.

[Marauder]

Your plane could be rigged to fly straight but still be out of correct rigging. No offense to the qualifications of the pilots you mentioned, but you need a qualified mechanic to look at what this plane is doing. My 1975 F is rigged right and will do over 150 TAS.

You also didn't mention what power settings you were using in cruise. What is your indicated airspeed at altitude? The are a ton of J owners on this site that should be able to compare power settings.

I have seen slow 77 and 78 Js, but even those are doing around 150 TAS with a 45/47 power setting.


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[201er]

8 hours ago, Sfurr201 said:

I recently bought a 77 J model that will not true out any better than 138kts. I didn't buy a mooney to do 138kts. I don't think it's rigging, the plane tracks and trims out great and everything seems to close up nicely, yes I put it on jacks and checked the gear. The engine has a little over 800hrs on it and all pistons are above 70. The prop is a hartzell schimitar with 250hrs on it. During a static run we could barely reach 2400rpm. We adjusted the prop to reach 2700 but made no difference in cruise.  We cleaned gapped and rotated the spark plugs, also had a small intake manifold leak fixed but all in all everything looks really nice. The engine starts well and runs smooth. Can anyone help account for the loss of rpm and nearly 25kts slower cruise speed? Could it possibly be a problem with the prop which I doubt? I am outside of Charlotte NC can anyone recommend a good engine shop near by?

You never said at what rpm, mp, altitude, temperature, fuel flow, egt. You didn't even say if it is kias, kcas, ktas, or ground speed. At certain power settings or altitudes, 138kts is great. If you are getting 138kias at sub 75% power in the mid 5-7 thousand feet, that's sounds about right. True airspeed would be around 150 depending on conditions which is normal for a J. There's a chance you are chasing an engine/rigging problem when in reality it's an expectations problem.

I typically get 150kts true airspeed on 9gph LOP at most altitudes 2500RPM.

[Marcopolo]

Sfurr,

 

  I am also based near Charlotte (Lincolnton, but live in Mooresville) and I travel to KMRN (Foothills AGL Aviation) 2 to 3 times or more a month.  If you decide to take your J there (and I think it would be a good starting point) let me know if you need any travel assistance.  Taking your Plane to Lynn at AGL or any other Mooney specialist could be the best first step as showing up at an engine shop looking for speed might get you more than you bargained for.  If it is in fact an engine issue or you just want to start there then I agree with DrBill and recommend Triad up in Burlington.   Lynn at AGL works with and has a very good relationship with Triad should he find the need to involve them or require their services.  Using a Mooney specialist to check the normal things, rigging, mag timing, compression, cam wear, etc may save you a bundle over an engine shop.  I took my K to Lynn for a rigging check (just to see, no speed complaints) and he found one aileron and the elevators out of spec, couple of knots...maybe, but having the full up travel of the elevators has definitely changed the feel of my landings.

Again, whatever you decide to do, if you need any assistance please don't hesitate to reach out, even if its just to meet up for a burger.

 

Ron

  

[mccdeuce]

I currently have my 78 J with Lynn at AGL and can say nothing but great things so far.  

+1 to have them take a look at her.

If it is RPM gauge issues I can help you out there. Currently have 2 electronic ones as I contemplate which I like better.