warrennn

My mechanic finally got a chance to look at the engine and found it to be in perfect health - no vacuum leaks, good compressions, good fuel pump pressure, etc. I am still guessing that it is water in the fuel, even though it didn't show up in the cup. For high altitude operations I need to think about isopropyl alcohol and make sure that my ADSB-in has a battery backup (so I can use the AHRS if the engine and gyros fail in IMC). Thanks for all your advice and help!

I am inclined to agree with the “dissolved” water explanation. I will let you know what the mechanics find (but expect them to find nothing).

Actually I have a digital fuel flow and TIT gauge (as well as digital cylinder head temp and oil temp). For nearly the entire 26 years I have owned the plane (and flown it between FL210 and 13000 on long flights) I have used a simple procedure to set power. I set the FF to about 13.3 gph and the TIT to 1520 degrees (and ~23", 2600 rpm at high altitudes and 30", 2500 rpm at low altitudes). Peak TIT is almost always 1600+. I don't have much interest in lean of peak (one of my mechanics, who is well respected, is dead against LOP). The previous engine lasted to 50 hours less than TBO and I have had remarkably few engine problems. I have looked into engine monitors and found them to add considerably to the workload (and also required a PC to download the data and I wasn't going to buy one just for this purpose). The mechanics will look at the engine in a couple of weeks. I will report back when they give their report. Thanks very much for your suggestions.

No, it is in a hangar at Paine Field in Everett, WA (KPAE). Ice in fuel or waste gate problems would be my guesses.

During these engine drop-outs, the manifold pressure would drop precipitously and immediately come back up to normal.

I had a turbo fail at 15k about 15 years ago. The manifold pressure just went down to 20" or so and didn't come back up. I returned to my home field and found that the exhaust pipe had slid out of the fixture and directed the exhaust at the front of the cowl (causing a burning smell). The thing was held in with wire wrapping which failed. It had also happened after takeoff when I smelled something burning and quickly turned around and landed.

Thanks! At one time I thought there was a chance we would not make it back but was able to divert my attention to getting on the ground in one piece. I do not have a Merlyn waste gate - just the stock fixed one. I do have a Precise Flight intercooler. I did consult with a mechanic on the field who thought I could make it back at lower altitude. My home mechanic also thought I was ok flying it back and he is very conservative. So far no FAA calls. For what it is worth, I didn’t use the E word.

The mags in the 231 are pressurized from the intake manifold (?). That cylinder head failure sounds terrifying! I must say, if I heard any "pops" from my engine, I would have looked for a place to land. When I had a mechanic at Eugene suggest a cause, he did a lot of web searches and spoke to the manufacturer and heard that the most common cause of what I experienced was a leaky waste gate. Well, in a few weeks my local mechanic will try to find the cause of the problem. Until then, I will keep out of high altitudes. wn

Thanks all for your prompt responses! Unfortunately, I didn't notice the FF. Some time ago, I replaced the FF transducer with one with a much smaller k-factor and the analogue needle hardly moves. I was so focused on finding a place to land that I didn't notice the digital (Shadin) fuel flow. I did notice large drops in the manifold pressure - I assume the FF was low as well. I have had high altitude mag problems about 15 years ago and the manifestation is very different from what I observed: there is a thump when the engine misfires. Even when the engine suddenly lost power, it was always smooth. Unfortunately, I don't have an engine monitor. I never run the engine LOP - it is always about 100 degrees rich of peak with a FF of about 13.3 g/hr. I am thinking that I had water in the fuel even though my fuel cup was dry when I checked before flight. Thanks again! wn

Last Monday I flew from Concord, CA to Paine Field in Everett, WA at 20,000 (to avoid ice) in my '79 231 with the TSIO360LB engine. I was getting a huge tailwind (>70 kts) and would have made the trip in < 3 hours. After 2 hours, the engine started misbehaving: it would nearly shut off and immediately return to normal power. It did this numerous times, with maybe 20 seconds between events. I got priority handling to land at Eugene, passing through a lot of IMC in the process. Below 10,000 or so, the engine started behaving normally and I landed safely. BTW, the controllers were extraordinarily helpful during the entire process. There are no full time available mechanics in Eugene, but one person did some investigating online and via the people at Teledyne and thought it was a leak in the turbo waste gate. My mechanic at home thought it might be frozen water in the fuel line. I had checked the tanks and found no water. I didn't drain the sump (mistake?) It is surprising that the engine ran fine and decided to fail after 2 hours if sump water were the culprit. I finally decided it was likely an altitude dependent problem and flew home at 6000 - the engine didn't miss a beat. I of course will not fly until the engine is thoroughly checked. I have an ESG ADS-B with a 2i ADSB in device which I use with Foreflight. I didn't realize the 2i doesn't have a backup battery. I will replace the thing with a 2s, which does have a battery. An engine failure would result in no gyros, which would be a problem - the HSI which Foreflight provides would be a big help in case of an engine failure in IFR. In my 26 years of owning this airplane, I have had only one other instance of a similar problem (previous engine). Nothing was found. Anyone have any ideas about what happened? Thanks! wn

In my opinion, the best iPad "mini" is an iPhone 6 plus! It also fits easily in one's pocket for use as a phone (who would have guessed?), calculator, reader, etc. It has pretty much replaced my iPad for most things. I use mine with WingX and it is much friendlier in the cockpit than my iPad Air, which is a bit large and blocks instruments. The Air is also easy to accidentally touch, generating spurious inputs. This happened on an ILS approach, causing the plate to disappear in a way which was hard to fix in flight (I now use Jepps for my primary charts -- the tablets are too unreliable). Warren Nagourney

I flew the plane today for the first time since the incident and the gear worked fine. Unfortunately, I also noticed that the checklist -- a standard Mooney checklist for an M20K -- had an entry for checking the emergency gear system!! I suppose that I have been ignoring this checklist item, perhaps thinking that it was not important. I need to be more scrupulous with checklists in the future!

My mechanic at my home field (Paine field, Everett, WA) finally jacked up the airplane and swung the gear repeatedly. He reported that there was absolutely no problem with it and it worked very well. I haven't flown it yet. I guess that the breaker saved the mechanism. Of course, I will add the emergency gear check to my check list and be even more careful when I do a final "GUMP" before landing, in case anything was weakened by the experience.

Tentatively, I will let the shop I have used for the last 30 years do the initial inspection (Crown Aviation at Paine field, Everett WA). They are currently busy and won't be able to do anything for the next two weeks. The next closest shop is in Bellingham -- they might be the better choice if a more detailed inspection of the gear actuator is needed. I will keep the forum posted on the results. Again, many thanks for the replies.

Yes, I have been a fairly avid consumer of this site, though I haven't contributed much (sorry). Actually, I have owned Mooneys for 30 years -- my former plane was a '68 M20C. I might let the folks at Command Aviation in Bellingham look at it -- they have a good reputation and are the only authorized service center in WA. I spoke to the owner (?) and he wanted to take the entire actuator apart to make sure there are no broken off gear teeth floating around waiting to jam the gear in a partially extended position. Sounds expensive.