sailon

7 hours ago, teejayevans said:

I have the STEC GPSS box, I overshoot a little, I am back on track within seconds, I slow down as soon as I hit the IF, by the time I make the T turn I try to be close to 100 knots, so I can be stabilized when I start the LPV GS descent. I can't get down and slow down at the same time. Are you making a standard rate turn?

Believe so.  Need to confirm.  I have had ATC instruct me to keep speed up over 150 kts when I flew a K model. Generally, I can slow down after I make the turn to hit Vfe and Vle.  Shouldn't the GPS time the turn based upon your speed and a standard rate turn?

I notice lots of STEC 50s in this thread.  I have an STEC 50 coupled to a GTN650.  I notice on RNAV approaches, that I am constantly overshooting (i.e., not turning fast enough) the 90 degree turn.  With GPSS steering, (forgot to mention I have Aspen glass), this puzzles me.  Is the STEC 50 or the GTN mis set?  I am entering the approach at 120 kts.  Too fast?  Thoughts?

A

Having recently been thru this myself with my F, Steingar has a good strategy, however, I would also add the following:  The last annual almost doesn't count.  It was done so that the seller can sell with a current annual, and items that don't affect airworthiness, but should be fixed (i.e., plugs at twice the service limits but still work) won't be fixed.  If you are not near a Mooney shop, give them a call.  I was very lucky, and was able to find the service shop that did the 7 annuals prior to the last signoff, and he knew my airplane very well.  The important thing is to review the specific Mooney gotcha's and get your mechanic familiar with them.  If your personal mechanic does not have any Mooney experience, I would recommend another personal mechanic who does.  Take your mechanic with you and do the PPI at the sellers hangar.  Moving the bird during pre-buy inspection time is a risky venture best left to the brokers.  Check that the bird is airworthy (compressions, detailed wing spar check, landing gear checks, etc.) Concur with the rest of the group to avoid the G and go for the E or F versions.  Good Luck!!

GTN650 GPS with GTX330 soon to be upgraded to a GTX330ES.  Have TIS display on 650 and love it.  For ADS-B in, I use the 113 dollar Rasberry PI solution with my iPad.

OK Verdect is in.  Cause of the issue was split between the harness with burn thru evident at the holders where they were too tight.  Replacement improved the situation somewhat, (had normal runup after 3 attempts, never got a good runup previously) but MK201TUrbo nailed it.  New plugs installed.  Perfectly balanced EGTs , 60 rev RPM drops both sides.  Flew for an hour with no issues, and a MUCH smoother running engine.  Measured the resistance of each plug.  One was 9000 ohms, a second was 200 ohms intermittantly jumping to open.  The rest were between 500 to 2000 ohms.  A new plug reads around 500.  All plugs had 830 hours on them.  Champion lifetime is 500.  Flew to another airport to gas up, rechecked mags prior to take off, no issues.  Thanks to the forum for all of your help!

1 hour ago, carusoam said:

Salon,

read up on spark plug resistance and champion spark plugs.  See if something there comes to light...

That is a more common type of failure.

Best regards,

-a-

Since my plugs are vintage 2002 models, replacement is way past due and just might solve my current problem.  Hi resistance definately makes sense, especially if the resistor is cracked.  Will advise after I install the new plugs.  Hopefully a short flight this weekend over the airport if success is reached!  

1 hour ago, Shadrach said:

I don't think you do either; I was asking Anthony (Carusoam) about his incident. 

WHEW.  Thanks.  I agree, My bird jumps off of the runway with a smooth running engine when it is hitting on all plugs.  

1 hour ago, Shadrach said:

Did your stuck valve reveal itself in the EGT data?

Not sure I have a stuck valve, this forum is leading towards an electrical issue.  As you said, hot EGT indicates a single spark.  Replacing all plugs this weekend.  We will see what happens.  Agree I don't want to fly it until issue sorts itself out.

14 hours ago, Smitty said:

Checking the P-leads is a good idea. Never hurts to make sure you're working on the correct magneto.

I think your problem is in the magneto. I know you said that a shop looked at it but a coil can test fine on the bench and then start acting up once the engine warms up. By swapping the spark plugs (assuming you switched the plugs with plugs associated with the other magneto), you eliminated them because the issue stayed with the same cylinder. By changing out the wire harness you eliminated a spark plug wire breaking down. A sticking valve would show up on both mag checks, not specific to one side. Also a sticking valve would be extremely noticeable during taxi and in flight. 

Good luck  

Thanks Smitty, issue is that the problem currently shows up with the engine cold. During recent ops test with the new harness, the right side failed initially, then passed after system warmed up and a few more tries with all even EGTs.  What I am starting to conclude is that there was a harness issue, (there was evidence of burn thru at one of the clamps which was so tight the leads could not be moved within it) as well as plugs that are old.  (16 years and 830 hours on plugs, electrodes are becoming oval).  I have ordered 8 new plugs, and hope to install them this weekend.  My theory (note MK201 Turbo comment above) is that the resistance of the plugs is higher than spec, with the proximity of the no 4 and no 3 cylinders to the engine mount and resulting vibration increasing plug resistance to disrupt the spark.  I will advise results after this weekend.  Mags only have 270 hrs since overhaul by the way. Certain that it is the right mag side, as it is the system that feeds cylinder 4 bottom which is the plug that was initially soaked in gas and is now damp.

37 minutes ago, jlunseth said:

I have one thought for you.  I see you rotated the plugs and also replaced the spark plug harness, so I assume you have a new harness.  However, it is possible you had an issue with the old harness.  The conductor goes bad inside, and/or you start to get carbon build up in the socket that the spark plug wire plugs into.  I assume that if that happened, the worst of it was spotted and cleaned up and/or corrected when the new harness went it.  The problem, though, is that an issue like that can create tracking across the cap, and once a track has built up you have a place for the current to go other than into the plug.  I would make sure the sockets and the distributor cap are thoroughly checked for arcing/tracking/deposits.

If "replaced harness" just means you put the old harness back on, then there is your problem.  Conductor is bad in one of the wires.

Since you have gas on the plug I would guess your fuel flow is ok, but it is possible there is some kind of intermittent obstruction in the injector or the fuel distribution system that leans the mixture out to the point where the cylinder won't fire.. 

It just sounds to me like you had an issue with a cracked plug, or a cracked connector in the wiring harness, but it caused some problem elsewhere, like in the cap, that you have not caught up with yet. 

Replaced harness refers to new distributor caps, wires, etc.  Could not find anyone who "rebuilds" harnesses anymore.  Seems the only way to replace the harness is to buy the whole ball of wax from someone like Spruce.

23 minutes ago, Shadrach said:

I can't say what your problem is, though my hunch is that it is plug related. Given the symptoms you describe, I would eliminate every ignition related possibility first as it does not read like it is fuel or valve related. EGTs don't run high on a cylinder with a stuck valve, EGTs run high on a cylinder that only has a single point of flame front propagation rather than two. For whatever reason, the plug for right mag, cyl #3 is dropping out. Did your shop actually disassemble the mag. Spinning the mag up in the shop environment is not the same as having it mounted on a vibrating engine. I've had intermittent coil failure that only manifest itself  at certain RPMs. I can't tell what's wrong, but I'd bet against anything external to the ignition.

Good insights.  Mag shop totally disassembled the mag, checked the inside, cleaned all of the distributor contacts, checked condenser and diode, and re-lubed it.  (based at KFIN, highly recommend shop by the way).  Good point regarding EGTs and stuck valve. 

1 hour ago, Bob - S50 said:

Just had a thought.  If it is always the right mag on #4, could it be a grounding issue at the plug?  That is, shorting out the plug somehow so there is no electricity to create the spark?

Even with new harness?

I have been giving some thought to the sticky valve issue.  Perhaps a compression test with engine cold, followed by warm?

One cylinder to a different cylinder.

Been having an issue with mag drops that doesn't quite fit other topics in the forum.  Here is what is going on:  Aircraft is a 68 F, I0360 A1A.  830 hrs TSMO.  Engine starts immediately, runs smooth on both mags.  MAG check results at 2000 RPM: 120 RPM drop on left mag, right mag 400 RPM with roughess.  Number 4 cylinder EGT totally cold when on right mag, could not be cleared when problem discovered.  Switch on both, now no 4 is hotter than other cylinders.  Plug in no. 4 bottom soaked in gas.  Pulled mag, had it tested at mag shop, and found mag was excellent.  (firing on all 4 with hot spark at 250RPM in test jig).  Diode and capacitor all tested perfect.  Rotated plugs, retested, still issue with cylinder no 4.  Replaced harness, retimed mags, now here is where it starts to get interesting.  First runup test, issue still there.  However, after 3 runup attempts, engine smoothed out, all EGTs equal at all times, 120 RPM drop each side.  Shut down, let cool for 10 minutes.  After restart, saw no 4 running hotter than rest at idle, runup failed with 4 going cold again, then no 4 started to fire and followed with perfect mag test again.  (120 each side).  No 4 bottom plug not soaked, but slightly damp with gas.  Mechanic and I are getting stumped.  Oil consumption acceptable.  (quart per 10 hours), boroscoped cylinders during pre-purchase and found valves and cylinder walls like new.  Potential issues could be:

Fuel Spider with diaphragm partially blocking fuel to no4?

Not leaning enough prior to runup?

Not getting engine warm enough prior to runup?

Cracked cylinder?

Other ideas?

Mechanic says to fly for a few hours, then take another look at no4.  Thoughts?

The FAA released proposed guidance for compliance with Part 23 today.  It is a draft version of AC 23-10.  Feel free to comment to the agency if you wish.   FAA Aviation Safety Draft Documents Open for Comment(http://www.faa.gov/aircraft/draft_docs/) for U.S. Federal Aviation Administration. This information has recently been updated, and is now available.

Find an instructor who loves windy weather!  Mine did, they are out there.  Go up with the CFI in gusty crosswinds when the CFI feels you are ready.  Best investment in your training you can make, and it is lots of fun!  .

YIKES.  I have been shadowing this thread, and feel I must speak up.  I obtained my instrument rating 11 years ago in Grummans and Pipers, have owned a Piper Arrow, which I was comfortable with flying "in the system."  THEN, my CFI let me train in his 252.  I thought I was comfortable with instrument flying.  Well there is instrument flying, and then there is instrument flying in a high performance airplane.  Also, there is training when the sun is out, and then there is actual IFR when the rain is flying.  IFR training is the mastery of procedures, and flying in the National Airspace System.  Throw a turbo Mooney into the mix, and you are adding speed control, engine management, autopilot management, and expectations that ATC places on fast aircraft.  To sum up, I had to learn instrument flying all over again when I stepped into the 252.  I just cannot comprehend attempting to learn instrument flight in a turbocharged Mooney.  Also, the examiner will test you on all of the aircraft systems during your instrument check ride.  (GPS, autopilot, etc)  Suggest you get your instrument in a basic Piper or Cessna without the fancy widgets, then move up to a complex aircraft.  At the risk of flames, a fixed gear Saratoga or 206 would be an excellent choice for your mission.  Now that I have been trained on the 252, I am enjoying my new (to me) "F"