Super Dave

I think this was just a short test hop with no leaning (is that right Kyle?). The drop off in FF is just a power reduction for descent/landing.

Yes, peak EGT is now over 1600º. Maybe Kyle can post some of the trouble shooting flights (thanks Kyle) where we did the induction leak test and LOP inflight mag checks. The three flights you referred to were flown by our other partner on his way from FL to WI. He typicly cruises WOT 100º ROP. The first event at :59 is i think, just a climb. There doesn't look to be a divergence of #2 EGT at that point. At around 2:15 It looks like he noticed something amiss and reduced power and enriched mixture. Then, after looking things over for a couple of minutes, left mixture full rich and went back to full power. In an effort to keep #2 EGT where he was used to seeing it, poor Scott flew the rest of the way home 200º ROP, burning fuel like an Ovation at F model speeds. I still don't buy that this is a fuel distribution issue. How would fuel distribution cause a cylinder that has always peaked in the high 1400ºs - low 1500ºs to now peak at 1600º+. Also, I don't understand how an engine with poor fuel distribution still has a Gami spread of .2-.3 GPH.

Probes have been swapped to rule this out. Anyway... To expand on Kyle's update: Lycoming told us not to worry about the high EGT. As long as other paramaters are normal, just keep running it without further investigation... Not exactly reassuring. I have one more half baked theory. When Kyle swapped the injectors, he stuck a borescope into the injector hole and saw some oil residue, sugesting that some oil being sucked down the intake valve guide. My theory is that the oil is mixing with the fuel and air, and is slowing combustion down a little bit so that we are seeing an elevated EGT. Similar to the way that retarding ignition raises EGT, or turning off a spark plug during a mag check raises EGT. Anyone buy it?

That's a good one. I spoke with a couple of different tech. reps. from Lycoming today and while he thought it was unlikely, one of the reps. sugested taking a look at that very thing. Our cylinders have double valve springs.

I agree that CHT is what we are trying control for the longevity of the engine, but EGTs can tell us a lot about fuel distribution, ignition, and valve health.

Maybe. We've never downloaded data from the JPI before, but we're looking into it now. Tempest massives; I haven't checked resistance since when they were new 150 hrs ago, but I've never heard of a Tempest failing the resistance test. Also, the mag checks sure make it seem like ignition is healthy.

If it were an ignition issue, I would expect to see the offending cylinder to show no EGT rise when one mag is switched off, and cold EGT/roughness (dead cylinder) when the other mag is switched off. But instead we see a normal EGT rise when either mag is switched off.

You got it. If we had not been so deliberate about swapping the probes, I would be convinced it's an indication error.

This would be true ROP, but a dirty injector would peak before the rest and have a lower EGT when LOP... Not what we are seeing. Also, a dirty injector would mess up the GAMI spread, and ours is still .2-.3 GPH

#2 has always been our hottest also, but not by much. We typically see 360s climbing out. Low 300s in cruise.

I need to understand more about sticking valves. I thought burned valves were a result of poor fit between the valve and the seat leading to a hot spot on one particular position on the valve face. The hot spot continues to warp the valve face in a vicious cycle until part or all of the valve face separates. I thougt sticking valves were something completely different where the valve does not open or close properly, but there is not necessarily anything wrong with the valve to seat fit, i.e. no asymmetry. Ditto on the ability to still run LOP, this whole thing is a head scratcher. if it were not for the engine monitor I don't think we would suspect anything amiss. Good CHTs, engine still makes good power and runs smoothly ROP and LOP. As far as consulting MX; one of the co-owners is an AP/IA, but other than doing the work on our Mooney for a little over a year now, he works exclusively on turbin equipment. Obviously, he's got good basic knowledge of piston equipment from A&P school, but his expertise is in kerosine burners.

First of all, thanks to all the responders so far, I appriciate the time and thought you are putting in to help another out. CHT has been unaffected. Coincidentally, we were due for a 500hr inspection on the left mag and pulled it off just after the trouble started. Mag was sent out, replaced and both mags timed to the engine. So, that rules out timing.

The probes were left wired to their original channel when the swap was made. This way, we could be sure that it wasn't a bad probe, wire, or connection. So, when we had the probes swapped we were actually reading #2 cylinder as #4 on the JPI. Will investigate sticking valve. When valves stick, do they stick open, closed, or in between?

I bet you're not as curious as I am! By normal rise, I mean that all cylinders have a roughly equal increase in EGT when doing an inflight LOP mag check. #2 is actually rising more than the other cylinders during the mag check, but it does so equally on either mag. EGT on that cylinder rises to near 1800° degrees during the inflight check. I can go nearly 100°LOP before roughness. All cylinders still peak almost simultaneously, it's just that the EGT values on #2 are way higher than the other values. Spark plug rotation was typical top to bottom, left mag to right mag. So, #2 plugs went to #3, and vice versa. I agree that it doesn't act like a burned/warped exhaust valve, and it doesn't look like one through the borescope. I was thinking more along the lines of the exhaust valve is somehow not completely closing when the engine is making power? Something like a broken/damaged valve spring?

Sory, forgot to mention the spark plugs; cleaned, gaped, rotated. Inflight LOP mag check- normal EGT rise on all cylinders, before and after rotation. Tempest massives with about 150hrs.

Background: IO-360 A1A with roller tappets, 650hrs since factory overhaul. Peak EGTs are typically high 1400s-low 1500s (20°BTDC timing). Recently, #2 EGT has increased, and is now 100°-150° higher than it has run in the past and now peaks at over 1600°. Here's what we've tried so far: Swapped probes, but high EGT stayed with #2. GAMI spread is still .2-.3GPH, and it will still run deeply LOP... but just to rule it out, we cleaned the injectors. Borescoped #2- exhaust valve shows no asymitry and looks to be seating normally. Compression check - 78/80. Tried an inflight induction leak test by recording EGTs at full throttle-full rich at 5000'. Then, reduced MP to 18" and noted delta in each cylinder's EGT. #2 EGT actually got a little cooler with the reduction, which is the opposite of what would be expected with an induction leak. Also, I don't think an induction leak could cause EGT to peak in the 1600s. I guess we're leaning toward exhaust valve issues, but like I said, borescope looked normal and compression was good. Is it possible for an exhaust valve to seat properly while static, idling, and at run up power, but then to somehow not seat completely while at full power? Any other thoughts on diagnostics? remedies?

Just like eating the third slice of pizza... I know I'll probably regret this, but I just can't help myself, so here goes. Increasing airflow will result in a higher fuel flow at peak EGT or any given degree LOP. So yes, a tuned exhaust will increase HP and TAS even at peak or LOP.

Approach lights in sight, continue...

I give up

rpb, please humor me and re-read the excerpt from from the AC that I posted in #61. Specifically, how do you interpret the subsections beginning at (1) and b.

I am familiar with the sources you referenced; I just disagree with your interpretation. I argue that AC 90-108 specifically states that you CAN use GPS distances in place of DME distances on approaches or other procedures. 7. USES OF SUITABLE RNAV SYSTEMS. a. Usage of Suitable RNAV Systems. Subject to the operating requirements in this AC, operators may use a suitable RNAV system in the following ways. (1) Determine aircraft position relative to or distance from a VOR (see first note in subparagraph 7b), TACAN, NDB, compass locator (see second note in subparagraph 7b), DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or Localizer (LOC) course. (2) Navigate to or from a VOR, TACAN, NDB, or compass locator. (3) Hold over a VOR, TACAN, NDB, compass locator, or DME fix. (4) Fly an arc based upon DME. b. Specific Allowances. The allowances described in this section apply even when a facility is identified as required on a procedure (for example, “Note ADF required”).

You could say it 100 times, but it would still be wrong. It it is perfectly legal and safe to fly a VOR/DME approach without loading anything into the GPS other than the VOR that the DME is based on. The approach is flown just as it would be without the GPS; tracking outbound and inbound is done with VOR equipment, but instead of identifying stepdowns, MAPs, etc... by the distance readout of the DME, the distance is simply read from the GPS. This isn't right either. If you are just using GPS-in-lieu-of-DME, CDI sensitivity has nothing to do with distance from the station.

I guess I'm in disagreement with just about everyone else on this one... I think ram air is fine in clouds or rain, just as long as you are well above freezing. Anytime you are flying through clouds or rain, there is plenty of moisture passing right through your air filter to be ingested by the engine. From my POH: "Turn ram air off if encountering icing conditions... Therefore, do not use ram air when flying in sleet, snow, rain, or moisture-laden air near freezing conditions"

I'll offer an alternative to the "baby in back-spouse in front" option. We started taking our oldest on trips in light planes when he was 3mos. old and still nursing. My wife would sit in back with the rear-facing carseat; that way if she needed to, she could take him out of the seat once we were airborne. Her habit was to start nursing 30 min from destination because we had read that nursing helps babies equalize their ears in the descent. Gear extension was her signal to strap the little guy back into his seat. Now that both kids are out of car seats, my wife still prefers to ride in back with one of the kids, while the other rides up front with me. With the front seat slid forwardish, she feels like the backseat is more comfortable than the front.

Maybe lean even more on the ground? You said you need to enrichen for runup, but I try to lean so much that the engine stumbles at anything over 1200RPM.