PT20J

Even without an engine monitor, you could collect more info. How rough is rough? Is it short duration or does it continue until you land? Have you ever had it happen and the not taken it to a shop? Maybe it goes away by itself and the things the shops do have no effect. Roughness can come from something that intermittently affects all cylinders or just one. A mag completely cutting out will cause roughness. Interruptions in fuel flow can cause severe roughness. Milder roughness is caused by uneven power outputs from the cylinders. You’ve replaced a lot of fuel and ignition components. I might be looking for a valve that’s beginning to stick. Skip

Are the two gauges completely independent including the transducer? The slow rising pressure on start up sounds like an instrumentation problem since it doesn’t always happen. Also, the fuel flow at idle is low and should result in high pressure. The pump is designed to produce sufficient flow as required by the engine and regulated by the servo. The pressure is not regulated - it’s whatever it needs to be. But it shouldn’t fluctuate if the fuel flow doesn’t change. Here’s a good video on fuel pumps: Also, from the Tempestplus website FAQ: Q: What is causing my fuel pressure to fall below the “green arc”? A: The most common reasons for low fuel flow/pressure are the following: 1. A worn or broken O-ring on the inlet side fuel fitting can cause an inlet suction leak. An inlet air leak will result in low Fuel Pump output pressure. 2. A weak operating spring in the Fuel Pump diaphragm assembly; 3. A worn fuel pressure gauge; 4. A clogged fuel vent or fuel cap; 5. A constriction in a fuel line either externally (a kinked hose), or internally (due to a collapsed hose lining). 6. Wrong fuel pump for the installation. Q: What is causing my fuel pressure to fluctuate? A: Fluctuating fuel pressure can be the result of the following: 1. A worn fuel pressure gauge; 2. A worn or broken O-ring on the inlet side fuel fitting; 3. A defective fuel selector valve (boost pump may labor); 4. An obstruction in the induction system (air intake); 5. A clogged or dirty fuel strainer; 6. Foreign material inside the fuel body (such as fuel cell sealant, thread sealant, or a drill shaving). Skip

Don Maxwell has a procedure on his website. But before shimming, make sure the motor mounts don’t need replacing. Also, most J’s look like the spinner is out of alignment with the cowling because the play in the camlocs allows air pressure to push the top of the cowling up and back slightly during flight. The cowling may look perfectly aligned after removing top and bottom parts and putting it back on and then look out of alignment after a flight. Compare yours with others in pictures and on the ramp. I believe @jetdriven wrote about mods he made to his cowl to fix this. Skip

We were flying the museum DC-3 northbound headed back to KPAE and needed to transition through KRNT’s airspace. I called the tower to request the transition and they replied, “Can we talk you into a low pass?” Never had a tower ask for that before. We happily complied and all had a good time. Skip

Since you have a flight director, you have a direct indication of what the autopilot is doing by watching the command bars and the annunciator lights on the KC 192. The FD command bars are simply a visual indication of what the autopilot is telling the servos to do. So, rule 1 is never engage the AP if the command bars are not “satisfied.” But, that doesn’t seem like what happened in your case. The normal sequence is approach armed (APR blinking), localizer captured and GS armed (APR steady illuminated), plane flies constant pitch (or altitude if in ALT hold) until glideslope centers, then, glideslope captures (GS iluminated, ALT cancels if it was engaged). To get a pitch up (assuming no autopilot fault) would require the autopilot to enter GS capture (as opposed to GS armed) with the command bars showing a pitch up command. When troubleshooting this sort of thing, I pick a good VFR day and just work with the tower asking to track the localizer inbound on repeated circuits which is much more efficient than working approach control for approaches. BTW, as far as the KFC 150 knows, an ILS and a LPV are the same thing. Skip

What’s a “cycle”? By ohms law, current = voltage divided by resistance (i.e., load). If the load is constant and the voltage is constant, the error is in the instrumentation. Skip

I’d get a Pantone and/or FED-STD-595 fan deck and pick a standard color that you like. Any good paint shop can mix colors from those palettes. Skip

Bob said he did the test on a M20K. He was mostly investigating what happens if you close but forget to latch the door. The results showed that it usually opened during rotation if unlatched. He said he unlatched it in flight during takeoff, climb and cruise all with no damage or handling issues. He did not try a high speed descent and he said he is aware of one case of a baggage door opening on a K during a high speed descent and departing the aircraft and striking the vertical stabilizer. Skip

I think there has to be more to the story. According to Bob Kromer, he did a flight test with a control rigged to pop the door open in flight and found no controllability problems and the door didn’t detach. So, something must have been defective — beyond whatever caused the door to open — to caused the door to detach. Skip

It doesn’t take much battery to excite an alternator. It sounds like you had the alternator tested and it’s fine. That leaves wiring or the voltage regulator. Since you measure voltage at the field terminal of the alternator, I’d bet on the regulator. Thirty years ago I had an OECO regulator fail on my ‘78 M20J. I replaced the power transistors and it worked fine after that. The hardest part was getting it in and out. Skip

And, speaking of lube... Mooney specifies Triflow. I always thought that this was because it contained teflon and would not attract dirt which wears out the bearings. But then I noticed that Triflow dries to an oily film. I looked up the MSDS and it is 25-50% Heavy Naphthenic Petroleum Oil (whatever that is -- but it sounds, er, oily). So I sprayed some on a piece of aluminum, let it dry a few days and dipped it in some dirt which clung to it rather well. So, I called RBC, which makes Heim bearings and asked what the recommended lubricant was for aircraft applications. Sales took a couple of days to get an answer back from engineering and the answer was MIL-PRF-81322G grease (Aeroshell 22). Edit: Someone will probably point out that some Heim bearings have zerk fittings. But I specifically asked RBC for a recommendation for the part number used for the connection to the aileron on a M20J which does not have a fitting. Skip

I've had similar things happen with water getting trapped in the static system. The pitot tube has a drain hole and less frequently traps water. Did you try the alternate static?l If you don't have drains, disconnect the static line at the instrument end and blow air through it toward the static port. Skip

This is interesting. Thanks for sharing that. According to this illustration, my hardware is correct but installed wrong -- bolt head should be on the outside. I looked at several EAA videos describing rod end use and they all used fiber locking nuts rather than cotter pins for control applications. Also, I understand that it has been standard practice at Van's Aircraft to use fiber locknuts on control rod ends for the entire RV series. I looked in a Piper PA28 IPC and Piper uses cotter pins on engine controls and some flight controls, but some have self-locking nuts. Mooney doesn't seem to use cotter pins in the landing gear retract system as suggested in AC 43.13. As I said earlier, if the fastener is properly torqued, I can't see that it makes any difference. And, since my trim bungees are in fine working order, and there are no logbook entries about work being done on the tail or trim system, it may well have come this way from the factory. Utilizing my "if it ain't broke, don't mess with it" philosophy, I'm going to check the torque on the bolt and leave it otherwise unmolested. Skip

Interesting point. I agree that any locking nut, properly torqued, should clamp the ball sufficiently to prevent rotation and loosening. However... Mooney uses castellated nuts with cotter pins on rod ends on all the engine and flight controls. The note 2 for the subject fastener combination item 44 in the IPC reads: All flight control rotating components must have double locking feature; castellated nuts, drilled shank bolts and cotter pins to secure each set of attaching hardware. AC 43.13-1B paragraph 7-122 b. states: Cotter pins are to be used on aircraft and engine controls, landing gear, and tailwheel assemblies. or any other point where a turning or actuating movement takes place. Skip

Good catch! I was so focused on the bracket that I didn’t even notice the hardware. All the control system rod end should have castellated nuts and cotter pins. I’ll fix it next week during the annual inspection. Thanks, Skip

Ferrying long distances usually involves installation of ferry fuel tanks. Perhaps this switch was installed for a transfer pump. There should be paperwork. You could also contact Mooney at technicalsupport@mooney.com to see if they have any info on the configuration as it left the factory. Skip

Mooney typically wires the avionics bus relay so that the radios are on when power is removed from the relay. The relay closes when the battery master is switched on, and the avionics master actually de-energizes the relay to turn on the radios. You can check by turning the master on, turning the avionics master off, and pulling the aux breaker. The avionics should come on. Skip.

Good questions. I think I recall Mike Busch writing that the cam failures he’s seen were usually running Aeroshell 15W50. When I bought my 1994 M20J a little over 2 years ago, it had a little over 1000 hours on the original engine and the cam was spalled. The first owner had previously replaced the cam at about 500 hours. It had always run on Aeroshell 15W50. This doesn’t prove anything, but I decided to run my new engine on Phillips 20W50. Besides, it’s cheaper. Skip

Have you checked the tach accuracy?

No, the timing could still be set wrong, it’s just that the A3B6D does have any options — it must be set to 25 deg. The timing is normally checked at every annual inspection. A single mag with retarded timing will show up as an excessive rpm drop during the pre-takeoff mag check. But the dual mags are mechanically connected, so they are timed together. There is internal timing in the mag (E-gap) that can be off and affect timing also. That would best be a job for a mag shop. But, it’s unusual for mag timing to drift enough to make a major difference in power. I would definitely check that the mag hold down hardware is correct and secure. There have been issues on the dual mag with it coming loose. Skip

Changing the timing also requires changing the impulse coupling lag angle so that the impulse coupled mag fires near TDC for starting. A3B6Ds have Bendix dual mags (that’s what the D signifies) and can only have 25 deg timing because that’s the only lag angle available with that mag. Skip

It is very confusing There is a series 2 CPC which has higher density than series 1 and uses the smaller pins. On my ‘94 M20J, Mooney used series 1 connectors. Not sure about later models. I seem to remember that my ‘78 J favored knife disconnects. Skip

These are for D-sub connectors that take size 20 contacts. The Mooney CPC Series 1 connectors take size 16 contacts.

Everyone has their favorite oil. Mike Busch likes single weight oils. RAM claims that the semi-synthetic Aeroshell multi-weights are bad. Phillips claims you can get lower oil consumption with it's all mineral 20W50. Lycoming is agnostic -- as long as it meets the appropriate MIL-SPEC, oil is oil as far as they are concerned. Some praise the LW-16702 additive in Aeroshell W100 Plus; some think it's bad stuff. Some prefer Camguard. Some sing the praises of Avblend. For what it's worth, I broke my factory rebuilt IO-360-A3B6 in on Aeroshell 100 and switched to Aeroshell W100 Plus for the first 120 hours and was consistently getting about 8 - 9 hours per quart. I switched to Phillips 20W50 with Camguard and now I get 12+ hours/quart. I've talked to others that had the opposite experience (worse oil consumption with Phillips). Skip

Courtesy of Wicks Aircraft: CAT – 1 ply neoprene impregnated fiberglass with very closely spaced spiral copper coated high carbon steel wire inside exterior wrapped fiberglass cord. From -85 degrees F to over 350 degrees F. Aircraft type. Maximum length 10 feet. (BLACK).SCAT – 1 ply same as CAT except with silicone rubber impregnation. From -80 degrees F to over 450 degrees F. Aircraft and industrial type. Maximum length 11 feet. (RED).CEET – 2 ply neoprene impregnated fiberglass same as CAT except wire between plies. From -85 degrees F to over 350 degrees F. Aircraft type. Maximum length 10 feet. (BLACK).SCEET – 2 ply same as SCAT except wire between plies. From -80 degrees F to over 500 degrees F. Aircraft and industrial type. Maximum length 11 feet. (RED). Attached Aeroduct catalog has everything you want to know about ducting. In the engine compartment, I use SCEET. SCAT is more flexible, but the wire always seems to eventually work it's way through the thin wall no mater how you terminate it. In the cabin, CAT works well and is very flexible. Guy @GEE-BEE can make you ducts in whatever length and diameter you want with professionally finished ends. They will last to at least TBO. Skip AERODUCT-Aviation-Ducting-and-Hose-Products-Catalog.pdf