PT20J

Valves don't burn because of high EGT. They burn when there is a problem with dissipating heat through the seat. Seat eccentricity (Continental has had some problems with this), sticking (both Lycomings and Continentals but more common on Lycomings I believe). High CHTs will impede the heat transfer. For longevity, control the CHTs and don't worry about the EGT except as a leaning reference. Skip

In my experience with Lycoming 320/360 series engines, leaning to roughness and the richening to smooth yields 25-40 deg LOP in fuel injected engines and near peak in carbureted engines (except for the PA28-161 which will run smoothly LOP). Skip

If you don't tape the edges, the bare edges of the aluminum insulation material can scratch the plexiglass (happened to a friend). Cloth tape is probably better than aluminum tape to tape the edges with something that won't scratch.

This is an interesting point. For an ideal Otto cycle engine, the ignition occurs at TDC and the mixture burns instantaneously at constant volume and then expands adiabatically (without loss or gain of heat) as the piston moves down on the power stroke transferring work to the crankshaft. In a real spark ignition (SI) engine, the mixture takes a finite time to burn and there is a rise in pressure to a peak and then a decline. The peak pressure position (PPP) measured in crankshaft angle (degrees after TDC) is determined by mixture strength, rpm and spark timing. There exists a PPP for each engine (based on engine geometry) that will produce the maximum brake torque (MBT). Operation at MBT produces the greatest efficiency. In automobiles, the spark timing is viable allowing PPP to achieve MBT over a range of operating conditions. Our engines have fixed timing, and the rpm is variable only over a limited range due to propeller efficiency. Thus, our primary control to affect PPP is mixture. LOP mixtures operate nearer the ideal PPP which is why LOP mixtures have the lowest brake-specific fuel consumption (BSFC). This all is just the physics behind why LOP is more efficient than ROP. For the pilot, it means that if you can get the same power (meaning true airspeed since that is what the power is converted to in cruise) running LOP as you can ROP, then LOP will be the more efficient choice. This is clearly apropos to turbocharged engines. For normally aspirated engines, if you can accept the airspeed generated by operating LOP at a particular altitude, then LOP is again your most efficient option. If you need to go faster and the throttle is already wide open, you will have to run ROP and accept the lower miles per gallon. BTW, the loss in efficiency from operating off MBT by 5 degrees or so is small, which is another way of saying the optimum operating point is broad. This is why Lycoming could change the timing from 25 deg BTDC to 20 deg BTDC without claiming a power loss -- the loss was absorbed in the tolerances permitted by certification. But the engine will produce slightly more power with the 25 deg timing. Chapter 2 of the attached document has some interesting description as well as measured engine data. Skip Maximum Brake Torque Timing.pdf

The Lycoming tube is plastic. The threaded end of the dipstick is metal. Crank it tight and the plastic threads deform and seize the dipstick. I've seen them so tight on flight school and rental airplanes that I needed pliers to get them loose. Just tighten them snug -- an eighth to quarter turn is plenty. I forty years, I've never found one loose after a flight. Skip

This is just one of those cases where it helps to understand how the systems work and how Service Instructions are created. Clarence's description of the system is correct. Knowing whether to remove or install the strap comes from understanding the ignition switch or reading the Bendix manual for the switch. The ignition switches come with the strap installed as the most common configuration is a single impulse coupling-equipped magneto. Way back in 1982 when SI M20-59A was written, Mooney realized that for the serial number ranges listed the link was installed and could be removed. That's all the SI covers. Later models (my 1994 M20J, for instance) were built with the strap removed. It was up to me and my A&P to figure out that we needed to install the strap when changing the engine from an IO-360-A3B6D to an IO-360-A3B6. Although Mooney shipped M20Js with both engines, it never produced a document detailing a procedure to change from one engine model to the other. The IPC does correctly lists the parts for both engines, but there are no drawings or instructions. Skip

Lycoming really would like to retire the A3B6Ds. It has lower parts commonality with other IO-360s per my Lycoming field rep. I got a discount for retiring a A3B6D core for a factory rebuilt (that’s technically the correct term) A3B6. There may be improved resale value with a rebuilt. From a buyer’s perspective, a rebuilt is known to be overhauled to new limits with new cylinders. A field overhaul could be done to service limits and have overhauled cylinders, so it takes some digging to know what you are buying. Keep in mind that “zero time” is just marketing. Lycoming takes in cores, separates and refurbishes serviceable parts and builds up rebuilt engines from that inventory. There is no way to know what time is on all the parts, so the FAA agreed to issue a new logbook and serial number. Skip

Sorry to hear about that, but you have company. I'm curious what oil has been used. I've heard that Aeroshell 15W50 doesn't seem to work so well in these engines even though it has the LW-16702 additive. Skip

Cliff, Hoppes No. 9 is a gun cleaning solvent. Find it wherever AK-47s are sold. Lycoming recommends it for cleaning fuel injector nozzles. Skip

Regarding the fuel flow transducer: I heard that cleaning it sometimes fixes it and tried that. Tried running some carb cleaner spray through it and that didn't help so I took it off and soaked it in Hoppes. That made it better, but it was still intermittent. The transducer is made by Floscan which was purchased by JPI a year or so ago. I bought a new transducer and that fixed it though I'm still puzzled that the K-factor setting on the Shadin had to be tweaked so much to get the right flow indication. At the time, it was cheaper to buy the transducer from JPI than Spruce, so check both prices. Regarding the tubing: I changed all mine to SCEET and got the SCAT out. The SCEET is double walled and much stiffer. Guy Ginby at GeeBee Aero N77GB@msn.com will make them if you send him the diameter and length. If you need a sharp bend NOT near the exhaust, you can get some short lengths of large diameter heat shrink tubing on eBay to shrink over it to hold a bend. Skip

The most fun was to fly beyond the mountains and do a 180 and look back a the little flat earth grid.

Anyone remember Bruce Artwick's original Flight Simulator (before Microsoft bought it) with the 2-D stick figure mountains running on an Apple II?

Flight schools like Hobbs time for billing purposes. BTW, the time you log as a pilot is different from the time logged for maintenance records. Per part 1.1: "Time in Service, with respect to maintenance records, means the time from the moment the aircraft leaves the surface of the earth until it touches it at the next point of landing." Most airplanes do not have an air-switched Hobbs meter, so most schools and rental outfits bill by Hobbs and record maintenance by tach time. The savings on using air Hobbs for maintenance was enough that the Part 135 operation I sometimes fly for installed air Hobbs in all the airplanes. The pilot flight time is also important in commercial operations because there are time limits on it, so the company got the FAA to agree to add .02 hours per landing to the Hobbs time to calculate flight time. Can we stop now? It's making my head hurt. Log whatever you think is reasonable. For Part 91 operations, no one is ever going to question it. Skip

No, that is part of your loggable flight time.

If you get a rebuilt from Lycoming, you get the roller tappets which I think is a big plus. All the radials had them and they don’t seem to suffer tappet or cam gear failures. The dual mag is getting expensive to maintain due to parts availability, lack of factory support and the fact that only a few mag shops will work on them. I decided to get an A3B6 and dump the dual mag. The threads on MS have the details you’ll want to know about if you change engines. The Mooney IPC lists the parts you need but there are no drawings. There are a few tricky things like figuring out how to properly rig the prop governor and you need to flip the oil cooler around 180 degrees. The A3B6 uses a different governor than the A3B6D, so it will need to be modified and overhauled or exchanged. It’s also a good idea to get the oil cooler overhauled - it’s not expensive. The Lycoming parts catalog lists a Mooney prop governor line but they refused to ship the engine with that line installed, and it’s several hundred dollars and several weeks to get them to make one. Most shops just bend the standard line slightly to clear the engine mount. That’s what we did. Lycoming ships the rebuilts with an alternator, but no starter. Don Maxwell has done several A3B6D to A3B6 conversions and is a good resource. Skip

Well, I think the object is to get a smooth takeoff with a minimum of fuss. As Bob Kromer pointed out at MooneyMAX last week, a steady 5 lb. pull during the takeoff roll will give a smooth liftoff. But, it only works if the trim is set right. Skip

According 14 CFR Part 1.1, Flight time means: Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing. So, taxi time counts if you go flying.

This is where to begin. If you are adding equipment, you should add a breaker for it. It might be better to have this done by an avionics shop as they are will probably do a neater job of it since that's what they do for a living. Skip

I have the Aspen AOA on my PFD installed by the previous owner. A good over-the-fence speed when light in my J model is about 65 KIAS. This puts the AOA indication clear into the yellow/black crosshatch area (critical). If I keep the AOA in the green, I’ll touch down in the next county. I’m curious if others using the Aspen AOA have the same indication, or if I should recalibrate it. As many probably know, the Aspen design uses a patented software algorithm to derive AOA from existing sensors rather than requiring a dedicated AOA sensor. Skip

Stall warning adjustment is covered in 27-95-00 for the M20J - not sure about others. Stall warning should activate at not less than 5 kts nor more than 10 kts before power off stall entered when decelerating not more than 1 knot/sec from a trimmed speed of 1.5 Vs. Should be checked in all configurations. Loosen screws to adjust vane. Moving the tip approximately 1/4” changes speed by about 5 mph. Skip

The stall warning is adjustable. Specs and procedure are in the maintenance manual.

Ross, it’s in Dave Roger’s paper cited earlier in the thread. And you really should get the 8KCAB out of the pattern - it’s fun there, but funner doing loops and rolls and such

This is not normal. Master cylinders have a coil spring coaxial with the shaft that returns the pedals to the upright position when the brakes are released. Sounds like either the spring is broken or something is interfering with the mechanism causing it to hang. Maybe Clarence @mooneydoc has seen this before. Skip

I read Dr. Roger's paper and found it interesting. I note that his original paper on the subject was published in the AIAA Journal of Aircraft. For those unfamiliar, AIAA is a professional organization of aeronautical engineers and technical papers don't make it to publication without review. Even without going through the math, the results make sense. Certainly, we all learned during primary training that the turn radius decreases and the turn rate increases with increasing bank angle. So if these were the only considerations, a very steep bank would be optimum for getting turned around with a minimum of altitude loss and lateral offset. But, we also should remember that power off descent rate increases with angle of bank which argues for a shallower bank. Given the two competing conditions, it makes intuitive sense that there would be an optimum somewhere between a shallow and a very steep bank angle. Dr. Rogers, using a little elementary calculus, shows the optimum bank angle to be 45 deg. As to the airspeed, it makes sense to use a minimum sink rate speed which is lower than best glide (maximum distance speed). The turn maneuver time is short and the airplane is decelerating so going from Vy in the climb to 1.05Vs during the turn probably averages out to somewhere around the minimum sink speed. And, of course, the slower speed reduces the turn radius. Skip

Great clarification, thanks. Whelen has both PMA docs and STC docs on their website. Can the lights be legally installed with a logbook entry because of the PMA, or do they require a 337 to apply the STC? Skip