SpamPilot

Actually, I did look closely. In this case it is scuffing, not torching, but thanks for the suggestion. The scuffing is at one specific point on the crown. Vertical witness marks attest to the scraping action. The normal carbon deposit ring around the bore at the top limit of piston travel has been scraped clean at this point. The bore is CermiNil and appears undamaged. Found a few slivers of aluminum in the oil control ring groove as well, though after removing them, the ring still sticks. I would inline the pictures, but, infuriatingly, neither the "insert image" nor the "insert link" options work when posting a reply to this forum (dialog boxes don't respond to either "OK" or "Cancel"). Nor do the "Paste" or "Past as Text" links work either. So I have attached pictures below. You can also find them in the Gallery. FYI, unless they have become stuck, rings normally rotate at about 1 Hz. The gaps are always passing each other when the engine is running, so the fact that they are or are not aligned is immaterial.

Had to make a precautionary landing (at an airport) due to falling oil pressure. Lost 3 quarts in one hour, oil pressure fell into the yellow but not below about 40 psi, 4 quarts left in the sump, still above Lycoming minimum of 2. No external sign of oil loss, but plugs on #4 were fouled with oil. Replaced the cylinder, found the old oil control ring was sticking in its groove, apparently due to varnish build-up. Also noted scuffing around the piston crown, some old spots, some newer and still shiny. Cerminil bore appears undamaged. Do I trust the remaining cylinders, or do I do a preemptive top overhaul? 900 TSMOH

Wondering if anyone else has seen this or has an understanding of the issue... I had removed the cowl on my '68 M20F to do an oil and filter change. Fortunately I was dawdling and in no particular hurry to complete this awkward and messy job. I gave my engine a good lookover and noticed that the firesleeve over one of the lines going to the oil cooler was torn open at one point. How could that happen? Then I noticed the culprit. There is a SCAT hose feeding the heater shroud running near this oil line with about an inch of clearance. It appears the oil hose has been beating against the SCAT hose for a long time, presumably due to vibration. The spiral wire in the SCAT hose had broken, leaving two polished and needle-sharp ends pointing at the oil line. These dug through the firesleeve. The only thing preventing the wire ends from chewing their way rapidly through the oil line itself was the steel braid armor over the oil line. One strand of the armor was indeed broken, not enough to permit a puncture, but obviously it was only a matter of time. I normally don't give much thought to SCAT hoses. In the future, I will. Needless to day, I took it straight in to my A&P to have the oil line and SCAT hose replaced. My question is: does the vibrating oil line signify anything serious? Or does it simply need to be tied down better? Oil pressure is totally normal and the gauge doesn't indicate any vibration. The oil cooler on this F-model is in the original location on the cowl and has not been relocated J-style.

Here's the final verdict on the hard starting predicament... My M20F now starts very reliably, hot or cold. There were two things wrong. As previously mentioned, the mag timing was off on one mag, causing firing before TDC during crank and very hard starting. The second thing was that the mags simply needed to be rebuilt and remagnetized. They just weren't putting out a hot spark. Now the mag drop is minimal. The excessive fuel at full rich turned out to be a red herring. This aircraft has a Power Flow exhaust, and I have since learned that you can't pass a mag check with the mixture set full rich when running a Power Flow (the motor will bog). You need to lean it a bit before the mag check. I am using one of two starting procedures: 1. Engine cold and zero fuel pressure: Fuel pump off, crack the throttle, set mixture to lean idle point. This is the point slightly rich of where the engine begins to stumble at idle. I have learned to set this reliably by the length of one of my fingers and holding the knob just so. Crank until the engine fires and comes up to idle. 2. Engine warm or hot, or cold with fuel pressure: Fuel pump off. Keep mixture in idle cutoff. If you move the mixture control even slightly out of idle cutoff with pressure in the fuel lines, it will dump a bunch of raw fuel into the intake and likely will flood the engine. Engine warm or hot: throttle closed. Engine cold: open the throttle a "big" crack. Crank until the engine coughs. At that point, continue cranking and advance the mixture slowly to the lean idle point. Crank until the engine comes up to idle. I have found that I can reliably start the engine on the first try about 95% of the time using these procedures. When warm, it fires within 1-3 blades. When cold, it can take 10 blades. I have not needed to add a priming step, even down to 25F, but I also preheat at every opportunity. I haven't had to mess with my idle mixture settings as a function of weather Full power full rich fuel flow is 17.0 GPH on my Shadin.

Here's what I know so far after bringing her into the shop... Left mag was timed to about 35 degrees (!). That means, even with properly working retard points, ignition is still happening something like 10 BTDC. That explains the prop stopping. This is probably the root cause of the starting problems. Both mags are now being overhauled. Additionally, the mag drop with the mixture full rich was found to be 200-300 RPM on either mag, not due to a mag problem but due instead to excessive fuel. I haven't been doing a mag check at full rich for a long time because I had been told by another A&P that this is not all that unusual. So I taxi lean, and then when I do my runup, I go a bit rich of peak power (but not full rich) and the mag check is OK. Haven't thought about it in a while. It appears that the fuel injection servo needs to be adjusted. That could have an affect on startability. Hard starting appeared to be more a function of density altitude than engine temperature, so excess fuel means the mixture would get even worse at high DA. This may also help explain the fuel dripping out of the left cowl flap (via the intake snifter valve).

As helpful as you guys are, I wish I were flying instead of writing to the forum... Since buying my '68 M20F a few months ago, I have learned quite a lot about starting techniques and have tried all of them. No technique is reliable for me when the engine is hot, or even just warm. Here's what happens on a typical start: 1. First crank will go for six or seven blades, then when I get the first hint of a cylinder firing, the prop stops cold and the starter motor just whirs (disengaged from the ring gear). 2. Second crank will go for three or four blades, then a cylinder lights off and the prop stops cold, starter still spinning but no longer engaged. 3. Third crank will go for two or three blades, then the prop stops and the starter motor disengages. 4. Subsequent cranks go for one or two blades if I am lucky, but usually the starter motor just whirs and doesn't even engage in the first place (as though I have run down the battery). 5. If I let it sit for a while, I can get another 3-4 blade crank, and maybe the engine will start successfully. If I get a jump start, the engine cranks noticeably faster and after 8-10 blades I can usually get it to fire up. I had the battery replaced (RG-35AXC) and the behavior didn't change. Battery voltage indicates a well-charged battery (12.4V+) even after several starting attempts. Battery voltage measured at the starter solenoid while cranking does not drop below 10V. I had the starter solenoid replaced and the behavior didn't change. Yes, I am using cold start/hot start/flooded start techniques as appropriate. Often I find excess fuel dripping from the cowl flaps. The problem happens even if the engine hasn't been started yet but the outside air temp is above 90F. However, if the aircraft has been sitting for two weeks and the OAT is only 75F, she cranks fast and, after a longish crank, she will fire up. I have plenty of evidence to rule out battery self-discharge or an external load draining the battery. TSMOH is 700 hours. The starter was replaced six years ago, still shiny. The mags (Slick) were overhauled during the major. Plugs are new. On my mag check, I get a 60-70 RPM drop on the right mag and a 80-120 RPM drop on the left mag, EGTs rise on all cylinders for both mags, and I get no rough running. Any thoughts or advice would be appreciated.

When I got my M20F 50 hours ago, the Positive Control (PC) system worked great. Love it. But it seems to be developing an increasing tendency to turn left. I can zero this out with the roll trim knob in the panel, but now the roll trim knob is cranked over to the right quite a ways. It's not rigging because when I press the button to defeat the system, the plane tracks straight and level hands off. The turn coordinator appears to be functioning normally. The Brittain user manual says the roll trim knob might need to be turned as much as 90 degrees off center to straighten the plane and they still consider it normal operation, so maybe this is "normal", but I think I'm getting past the 90 degree point. Anyone else have this happen to them or have any ideas?

I'm also inching towards my Commercial in my M20F. One thing bothers me. Steep turns, chandelles, and lazy eights (not to mention spins) are all aerobatic maneuvers. The Mooney Type Certificate explicitly prohibits aerobatic maneuvers for every model of Mooney (see the "Notes Applicable to All Models" section of the TC, search for "aerobatic"). In comparison, aerobatic maneuvers in a Cherokee are only permitted "provided it is loaded within the approved weight and centre of gravity limits", and then "the approved manoeuvers are spins, steep turns, lazy eights, and chandelles." (ref. Piper Aircraft Corporation Service Bulletin No. 753) How can we be in compliance with the FARs if we do these maneuvers in an aircraft for which they are prohibited? My CFII did his Commercial checkride in a Mooney. I assume he's not the only one. "Everyone does it" does not prove it's legal. "These maneuvers should be safe as long as you remain coordinated" is a reasonable response, though again it doesn't address legality, and is definitely not the same as "if you make a mistake, the aircraft can be recovered".

It has been six weeks since my original post and I have clocked another 30 hours (awesome plane!). I had practiced landings with my instructor shortly after that post and it was a total anticlimax. My landings were boringly good. So I still don't have any solid conclusions about my original post. Nevertheless, I have learned a lot over the intervening flight hours, including: - I find it much easier to land the plane when it is heavy. Both the tendency to float and the tendency to bounce are reduced considerably (I believe these are related but distinct issues). Having one passenger makes a noticeable difference. Three passengers and the plane sticks nicely on landing. It feels like there is a significant reduction in suspension recoil when landing heavy. - AOA control needs to be very precise in the flare. A hair too much yoke backpressure will cause the plane to leap into the air again. Compared to my old Cherokee, the yoke motions are one half to one quarter what they were. With the aircraft heavy, it is more forgiving. When light, it's a very fine line. - Even in the landing configuration (I use full flaps), the aircraft still gives up speed very reluctantly. Getting weight on the wheels after touchdown remains tricky, even though I'm dumping the flaps. I am getting better at anticipating this, but I have to let the plane roll out a lot farther than I am used to before I can start applying the brakes. - Compared to the Cherokee, I find I have to be zealous about stepping down my altitude and speed on final. If my pattern speed or altitude are too high before turning final, it's too late. If I'm not down to 90 MPH as I reach short final, it's too late. If I'm above 85 MPH over the fence, it's too late. If I'm not at 80 MPH over the numbers, it's too late. That's a bit exaggerated, of course, but when I fail to fly by these rules, the quality of my landings suffers immediately. I can't cover up flawed technique and salvage awkward landings like I could in the Cherokee. - For short fields, I am working on changing my aim point from the numbers to the edge of the runway, or even well into the grass. - I knew the plane flared lower than the Cherokee, so I focused on getting the sight picture similar to what I see while taxiing as I touched down. The mental leap I made recently was not to even *begin* the flare until it seemed like I was about to auger in. Again, an exaggeration, but it helped me reorient myself towards flaring *into* the correct sight picture, not flaring first and then letting the plane settle into the correct sight picture. I haven't had any bounced landings since my first post, though I haven't flown that light, either. I have had a few minor floaters, but no go-arounds. There hasn't been any one thing to work on, it was simply a process of making small adjustments to *all* of the issues and getting more consistent across the board. Oh, and one more thing I learned. If I don't fly more than once a week, all my landing senses get dull. If I don't fly for two weeks, I'm back to relearning everything.

I'm still waiting for decent conditions to get back in the air. Let me say in the meantime that all this feedback is a tremendous help. In each of my four bounced landings, the nose wheel never touched, at least not on the first bounce. I distinctly remember the airplane "dropping" right before the bounce. The nose was up, but given that the stall warning horn was not going off, I probably had additional elevator authority and could have softened/eliminated the bounce by a touch more backpressure on the yoke just at the right time. The reason that I might have been reluctant to increase backpressure could be because I noticed, in the flare, vertical speed is extremely sensitive to angle of attack. Just a hair of additional backpressure and the plane wants to get airborne again. I am thinking it's even more sensitive at low weight. Slower speeds should mitigate this pitch sensitivity somewhat. I really appreciate the comments from those pointing out that maybe the airspeed indicator is leading me astray for one or another reason and a little stall practice at different weights will help to establish the true stall IAS. I also like the comment about the plane being very light on its feet with full flaps. Especially with the low weight, that's definitely how she felt, like the proverbial butterfly with sore feet. I intend to try different flap settings with my instructor to understand if that's another tool I can use, or if it's not advisable.

Surely there must be many dozens of threads on this topic. But I'm new to the forum, and searches on "landing technique" or even just "landing" result in no hits. In my short (250 hours) flying career to date, I have only had one bounced landing that resulted in a go-around. Now 20 hours into having a Mooney M20F, including 15 dual received, with nary a problem other than getting the aircraft slowed down from altitude, I get four bounced landings/go-arounds in a row. I had previously read all the advice I could find on landing Mooneys. I am well aware that speed control is essential. Wind was calm, the runway was plenty long enough, the plane was light (me and less than half fuel). The first three times I came in over the numbers at the recommended 80 MPH/70 knots (yes, I was paying close attention to airspeed). I had a nicely controlled sink rate, low power, full flaps, and full nose up trim, flared, brought power to idle, held the nose off as the plane slowed, and... boink! The plane dropped, but only by a matter of inches. In my Cherokee, the struts would have dissipated the energy of such a small drop, but the rubber discs of the Mooney sprung the plane back into the air. The bounce was small enough that I felt comfortable letting the plane settle back to the runway, but on the second touch it boinked again and I was out of there. On the last attempt, I figured I was light enough that I could come in over the numbers at 75 MPH. The plane boinked once, I let it settle, it just barely boinked a second time, so I risked letting it settle a third time (please do not follow this example), it boinked again and I could tell a porpoise was starting, so I got the heck out of there. The airstrip was new to me in this plane (though I have landed a Cherokee there many times before) and is known to have a few undulations in the surface. Flying light in the Mooney was also new to me. At no time did the stall horn go off. I think the most likely explanation is that I still don't have the sight picture quite right. I definitely don't have the feel for setting the plane down gently after a small initial bounce the way I would in a Cherokee. I have already scheduled more time with my instructor. Would love to hear words of advice (encouragement?) from others on the forum...

Not sure my experience is typical, but the manual gear on my (new to me) M20F is light and easy to swing in either direction. A pleasure to use, in fact. After reading the various commentaries on how it was important to do it in one smooth motion while quickly adjusting hand position, and of other peoples' difficulties, I had steeled myself for an awkward and difficult experience. I gave myself cramps the first couple of times I tried to do it according to the recommended technique. But it turns out I can take my time and there's no drama or excessive force required. I calmly unlock the thumb button, push the grip down to get it out of the latch, and the bar swings gently on its own about halfway with little effort on my part. In my aircraft midway is a neutral position, and the bar will simply stay there if I let it. I don't bother anymore trying to do all this in one smooth motion. Rather, I take my time at the midpoint, adjust my hand position so it is comfortably on top of the lever, and then push down to the floor. I doubt I put more than 10 lbs of force on it to get it down. Then I take my time pushing the grip into the floor latch, and double-check to make sure it is latched (and then recheck a third time a little later). I keep the aircraft near Vx until I have retracted the gear, so that helps. But the few times when I have retracted at Vy have not been much different, maybe a little harder to push the bar to the floor. I have been advised that tapping the brakes can help, too, since then you aren't trying to move two spinning gyroscopes. I keep forgetting to do this. I have also been advised that my Mooney has "one of the sweetest swinging gears" ever. I understand it's primarily a matter of preload, not lubrication so much. YMMV.

My new M20F flies well and appears to be putting out full rated power. But I have yet to see an honest 2700 RPM on the tach. 2625 is the most I can get in cruise, even at low altitude. It's a digital tach so I doubt this is an issue with tach error. I don't intend to do a lot of cruising at 2700, so it's not a big deal, but I'd still like to know why I can't get that last 75 RPM. Any thoughts? Maybe a cable or prop governor adjustment?

In my M20F with manual flaps, it takes something like 15 seconds for the flaps to retract fully. It would be nice for them to retract faster once I'm on the ground to help transfer weight to the main landing gear. Can anything be done?

Resolved. There were two main problems and a couple ancillary issues. The first problem was that whichever numbskull did the wiring harness in the engine compartment ran the EGT probe wires alongside the spark plug wires. Crosstalk from the spark plug wires coupled into the EGT probe wires, causing a fluctuating reading on both the factory and GEM EGT displays. By simply spacing the wires away from the ignition harness, the fluctuations went away and the readings are now nice and steady. The second problem was that the GEM EGT probe had an intermittent failure and needed to be replaced. Additionally, although not a contributing factor to the original problem, I discovered that the GEM EGT display had not been calibrated correctly. It was reading far too high, giving misleading information about actual EGT. Finally, the backfire/popping sound on startup has completely disappeared now that I have figured out how to start and idle the motor without choking it with fuel.

As a new Mooney owner, I'm looking to join groups such as MAPA. But can anyone tell me if they are still in business? What's up with forcing me to create a PayPal account in order to pay for a membership? That's not very welcoming. And why have there been exactly zero Verified Buyers purchasing memberships or anything else from them in the past year, according to PayPal? Plus, the last announcement on their home page is eight months old. Looks to me like nobody is home.

Hm... The engine has a tendency to pop every few seconds at idle after startup. I assumed this was occasional backfire out the exhaust due to far excessively rich mixture, since I can pretty much eliminate it with a mixture pull (and going full rich audibly bogs the motor). On the other hand, if #3 has a sticky intake valve, then maybe it's backfire out the intake that I am hearing. A sticky intake valve could maybe explain both the lower compression reading and the low EGT reading as well as the backfire.

I had my A&P/IA take a quick look at the probe from the GEM. He says it looks fine. While he agrees it would be odd to have the GEM probe and the factory probe fail at the same time, he is confident it is either a probe or wiring issue. I did just notice that cylinder #3 (the one with the EGT fluctuation) had the lowest compression on the last two checks. The compressions (hot) were 74/78/71/75 three weeks ago, and 75/75/70/76 four months ago. The cylinders were borescoped during the prebuy inspection and nothing unusual was noted. All the spark plugs were replaced 15 hours ago.

Great suggestions. I inspected the engine carefully and found no evidence of any exhaust leak anywhere. The stacks are on tight and the studs and nuts appear to be in good shape. The #3 exhaust gasket is in good shape. Actually the entire engine looks quite clean. The analog CHT meter is on cylinder #3 with its own probe located just above the GEM 602 EGT probe. Switching probes 1 and 3 is going to be a problem as the leads for the probe on 3 is not long enough to reach to 1, but I suppose I could put probe 1 into cylinder 3, cover the hole, and leave probe 3 tied up just to see if probe 1 reads the same way. The probes themselves all appear to be in good shape. I have not checked connections at the 602.

Hello Forum, I just bought my first Mooney (a '68 M20F with J windshield, cowl closure, and other mods). What a great plane. But on the 15 hour flight back home, I noticed EGT readings I didn't understand. I was wondering if anyone on the forum had any thoughts on the issue. The plane has an Insight GEM 602 for EGT and CHT on all cylinders, plus an analog EGT meter in the panel. After engine start, EGT's and CHT's come up evenly across all four cylinders, and come up further during the runup. In climb running full rich, they remain fairly even across the board, and CHTs remain around 375F. But once I configure for cruise and lean conservatively (10% richer than book ROP fuel flow for my chosen power setting, measured with a Shadin fuel flow meter), the EGT for cylinder #3 starts acting up. It oscillates, plus or minus 50F at first, and then gradually the oscillations increase until after an hour of flight they are going from bottom to top to bottom of the EGT scale. The temperature will drop off the bottom of the scale for maybe 5 seconds, and then will shoot to the top of the scale and stay there for another 5 seconds. After 2 hours, the reading biases towards the bottom of the scale, and eventually the EGT drops off the bottom of the scale and stays there. The analog EGT meter in the panel does not quite follow the same pattern, but it's similar. It reads around 1200F through the runup, then flaps around rapidly in flight so much it is impossible to get a solid read on it. It never goes above 1200-1300F. Then it starts reading colder and colder and eventually it, too, falls to the bottom of the scale (<800F) and stays there for the remainder of the flight. I do not know which cylinder this EGT is reading. I assume it is cylinder #3. The EGTs on the other 3 cylinders are all steady and respond as expected according to the GEM. CHTs on all cylinders, including cylinder 3, are always steady in the 375F range. Cylinder #3 CHT is no different than the other cylinders. The engine otherwise seems to run like a clock. It only has about 650 hours on it SMOH (Penn Yan). The aircraft cruises at 150-155 KTAS at around 65% power and 10000', so it seems to be putting out full rated power. There are no unusual sounds or smells or rough running. Any ideas?