Search the Community

Hello all. Over the last 4 or 5 months, I have noticed my CHT's have been steadily rising and the spread from the hottest to the coolest is increasing as well. (Used to be 30 degrees, now it varies between 35 & 40) It is to the point where I can't fully close the cowl flaps. This hasn't been an issue for the last 250+ hours on the plane over the past year and a half. This is when I started running LOP. I have an M20K/231. Inner-cooler and 'automatic' wastegate & GAMI injectors. I took the first picture this morning while flying from Phoenix to San Diego. LOP, 12k, Cowl flaps in tow (Fully closed and CHT's go over 400) The second pic is almost a year ago to date. LOP, Cowl flaps closed, not sure altitude but probably pretty close to 12k. I know It was running about 45 degrees more LOP a year ago, but the CHT's are much cooler with the cowl flaps closed than they are now. What could/would have changed over the last year? (Compression check 2 weeks ago showed about same as annual in Nov. Any help would be appreciated!

Hi all, I am a proud new owner of a 1980 M20K 231. A bit more than I need, but I hope to grow into it. I have been reading this forum as a guest for a while and have just signed up to hopefully get some answers from some experienced and willing people. Keep in mind, I am very green. This is my first airplane and although I started flying over 10 years ago I have only been licensed for a couple years. So still learning lots, and trying to read as much as I can. Just a quick run through: I have the TSIO-LB360. It is at about 1000 hours SMOH and was taken apart in 2013 due to a prop strike but I don't believe anything was replaced. It has the Merlyn Wastegate, an intercooler, an EDM700 engine monitor and GAMI injectors. I also have a Shadin Fuel Flow indicator. First question should be a fairly quick and easy one. I flew with some passengers for a couple of hours. Arriving at my destination I had to overshoot the first approach and when I selected the gear up, it wouldn't go up. After cycling it a couple of times with no response I checked the circuit breakers and noticed the "Gear Act" breaker popped. I tried resetting it, and it popped again immediately. Luckily I am old enough to know not to keep trying like I would have in my younger days :-P My rear passenger noticed that the safety latch (metal cover) was open on the emergency gear release so the handle was exposed. I guess one of the rear passengers knocked it with their foot. I closed it, then reset the breaker and everything was back to normal. I assume that they are interlocked? I have done a couple flights since and there have been no issues. Everything functions normally. I can only assume that was the only cause and I don't have anything to be concerned about? Input? Next question should be reasonably simple as well. When I bought the plane the gear warning horn did not work. We had the manifold pressure all the way back (at altitude) and were not getting anything. Before we finalized the deal, the mechanic adjusted it based on some throttle position/manifold pressure readings which we took during the flight and he fixed it perfectly. It would come on at exactly 14.9" of MP. Except that later in the flight it came on slightly less than normal cruise power settings. It would go off eventually if the throttle was moved in and out, and sometimes if I wiggled it side to side gently or twisted the knob (it is not a vernier) it would also go away, but not always. This is somewhere in the 20-26" range so just below normal cruise I guess. I notice it on descents or in the circuit more than anything. Is this an easy fix? I was told that a Mooney expert from Tri City Aero in Kitchener Ontario frequents this forum and may be able to give me some input. I am just in Burlington and plan to give him a call soon to start our potentially long and expensive relationship The last question I have relating to LOP operations may spark more debate (given all that seems to be out there on the topic which has been beaten to death) and probably has no simple answer but I am just looking for a bit of input, not something complicated and I will do some more research myself. Just trying to figure out where to start. My instructor told me to run ROP with TIT up to 1500. I have seen lots in favour of running LOP so I have experimented a bit running LOP. A couple days ago during cruise at 28" I pulled the mixture back to just under 9GPH. That's where it starts to run a bit rough. I bring it back up to about 9.5 with a TIT of around 1450-1500 or so. I have been told, and gotten into the habit of monitoring TIT closely, but have recently read an article that swears by leaning according to CHT. I do know that CHT's are even more important and have a very close relationship with ICP. Here is what happened. After only a few seconds... maybe 15-30 (I wasn't paying super close attention), my #4 cylinder CHT skyrocketed quickly. On the JPI the middle bar that separates the CHT and EGT appeared to be flashing or basically just started going up and up. Then I got the flashing indicator for that cylinder and the display stayed there and I think the temperature was in the 420 range. I panicked and enriched the mixture quickly and everything went back to normal. I thought maybe I was too lean, and tried it again paying closer attention to things, and the same thing happened. It seemed to happen in less than 10 seconds. What I am looking for from some of you experienced guys is the answers to some of these questions... Is this a sign of pre-ignition or detonation? Is this a bad fuel injector? Do you think I caused any damage in those few seconds that it ran like that? Could it be a bad sensor? Is this a result of running LOP? I can only assume so since it doesn't happen when I run ROP (about 1400-1450 TIT and 11.5-12GPH) Any input on this would be greatly appreciated since this is worrying me quite a bit. I know there is likely more to it than a simple explanation but I appreciate any information that anyone is willing to give. Thanks in advance and I hope to be able to post here and look forward to being part of this community. I just love my plane!

I fly a M20K 231 with Merlyn intercooler and wastegate making it fly like a 252. We recently had an engine overhaul that caused the TIT to run considerably hotter than on our "old" engine. The "new" engine is in fact the same core, just overhauled to new specifications. The temperature probes are the same as well, so they may be inaccurate, but they should be measuring the relative temperature differences correctly. We had a Mooney Service Center set the fuel flow system at the high and low end per the Continental Service Instruction. This supposedly is very important because an out of whack setup could create many problems. At full power on takeoff (36 inches due to the intercooler), we are seeing 22 gph. That is about 2-4 gph lower than before the overhaul. In cruise (28 inches, 2500 rpm, mixture full rich) we get 15 gph, about 1 gph more than on the old engine. The really concerning thing though is that with the mixture full rich, we see TIT temperatures between 1520 and 1560. We have no ability to decrease that temperature by running significantly rich of peak. On the previous engine with what was probably a poor fuel flow setup, we could cool the TIT to less than 1480 degrees by enrichening the mixture. So my question to the community is 1) should we be concerned with flying the airplane in cruise at 1560 TIT, and 2) should we be concerned that we don't have any "mixture authority" at normal cruise conditions in case CHTs start rising or something like that. The STC that added the intercooler was approved without any change to the performance charts, so we don't know exactly what fuel flow would be expected with certain power settings. If anyone has a copy of a 252 power chart, it would be most appreciated. Thank you.