PT20J

Thanks for letting us know the outcome.

They quoted me two full days to do a prepurchase inspection. Plane was sold before I got that far and I bought one in Texas. Don Maxwell did a thorough inspection in about 6 hours. I’ve heard good things about Troutdale OR MSC. Skip

I’m going to have to do this this winter. Anyone tried 3M General Purpose Adhesive Remover? Skip

You are allowed a maximum dent of 1/32”. If it needs to be replaced, I’d see if I could retrofit the newer design with stops. Skip

The reason to torque a bolt is to stretch it a predetermined amount which gives it optimum fastening capacity. The proper way to torque a bolt is to torque the nut if at all possible. Torquing the bolt can result in low torque due to added friction and also wears the cad plating off the shank. Nonetheless, occasionally it’s the only way to do it. For self locking nuts, you are supposed to measure the run up torque and add that to the torque value.

Only a few bolts -- usually in engines -- are one-time use. General purpose hardware can be reused unless it's been over torqued and stretched or otherwise damaged. Lock nuts can be reused unless they run up finger tight. But, hardware is cheap and if you don't know the history of a fastener it's probably best to use new. Years ago during a factory tour someone told me that Al Mooney had calculated that he could use a size smaller on the upper engine mount bolts but thought it didn't look right. Here's the info on the nuts for for the baffles from the Lycoming IPC. BTW it's best to check all the mounting details with the IPC and Maintenance Manual. Don't just put it back the way you found it without checking because the last person may have done it incorrectly, which is not uncommon on Mooneys I've learned. Skip

If you are changing from an A3B6D to an A3B6 don’t forget to put the strap on the ignition switch to ground out the right mag during start. Skip

You can also make a funnel from a plastic Coke bottle. The threads mate with the Lycoming dipstick tube. Screw one on and cut the bottom off at the appropriate angle with a box cutter.

Might be true for a C or D as indicated in the reference. The J service manual is different. As I said, we had no problem R&R ing the engine without removing the engine mount from the airframe. Skip

I don’t think you can mount the pedals without the brakes — they will flop down since the brake linkage adjusts the pedal angle. I’d make some wood blocks and mount them temporarily for practice. Then you haven’t really permanently modified the airplane.

Scary. Glad it worked out OK.

The engine comes bolted down to a pallet covered with wood frame and heavy cardboard and a foam "donut" on top of the engine inside the carton for cushioning. Unless the carton is seriously damaged, everything inside will be OK. The tip 'n tell is a little arrow with plastic beads that can only flow one way and indicate if the carton has been upended. Open carefully as you will need the carton to return the core. We had the driver wait until we opened the carton and made sure it was good and then we signed for it. Unbolt the engine from the pallet and lift out with an engine hoist. Put the old and new engines side by side and transfer parts you are reusing from the old to the new. Commonly missed are the fitting for the oil pressure sender and the sniffle valve. Install all the components on the accessory case -- it's much easier now than with the engine installed. And don't lose the barrel nuts used to bolt the baffles to the cylinders -- they are special Lycoming parts (Spruce stocks them) and cost $35.60 each. (I spent an hour looking for one that fell out of the cylinder and rolled across the shop floor into oblivion). Baffles can be attached with the engine installed. When you remove the old engine mounts, note the position of the shims so you can reassemble with them in the same position. Use new LORD mounts. Some install the engine mount to the engine and then the whole assy to the firewall. We didn't do this as the engine mount was in good condition and we never removed it or the wiring attached to it. We had no trouble attaching the engine to the mount on a 1994 M20J. Skip

Rule 1 is never ask the FAA a question if you can’t stand to hear the answer. A big problem with the FAA is the autonomy granted to the regions in setting local policy. The STC was clearly intended for major changes. The first sentence on the second page of the legal interpretation emphasizes that. As such it makes sense that a 337 is required when implementing an STC. The problem is that some regions required STCs for simple things- like Rosen sun visors. Other regions allowed such things to be done by simpler means like PMA. Now the FAA has a problem because of these inconsistencies. I’m sure headquarters isn’t all that interested in issuing an opinion that says all those FAA Approved STCs are wrong. Though the opinion seems to say that an STC that doesn’t meet the definition of a major alteration does not require a 337, I think the safest course is file a 337 if an STC is involved. No one will ever question it. As Don Maxwell once told me, “It’s just a piece of paper.” To be clear, I agree with Byron and the interpretation letter — it’s the FAA’s misapplication of the STC for minor alterations that has caused any confusion that exists Nonetheless, many IAs and local FAA inspectors will insist on 337s. Skip

Seems like door seals are a common leak point for CO. I know my door seal needs replacing -- it's original from 1994. I'll fix it this winter when I do some interior work. But recently I started getting readings on the Sensorcon of 50-60 ppm. I dressed the seal with some silicone grease and it went down to less than 5 ppm. Skip

According to Mike Busch's column in the October AOPA PILOT, a 2009 legal interpretation from the FAA says that the list of preventative maintenance tasks in 14 CFR Part 43 Appendix A (c) is not all inclusive. You may be able to do more than you think. Skip Coleal - (2009) Legal Interpretation.pdf

The Lycoming part interferes with the muffler location. Mooney makes the right angle sniffle by modifying an AN fitting to insert a plastic ball and hold it in place with a small pin. If you suspect the sniffle valve is stuck open causing an induction leak, you can test it by temporarily plugging the drain line to see if that makes a difference. Skip

I think the late Richard Collins had the best handle on GA risk management. First, he accepted that flying was inherently risky. Then, he analyzed years of accident data to determine where the greatest risks were and did his best to avoid or mitigate those risks. Everyone has different risk tolerances and different reasons for making a particular flight. There are certainly greater risks in flying at night, over mountains or in IMC. But, there can also be great benefits and each of us has to weigh the benefit vs. the risk of our flying activities. I believe statistically, most accidents happen on takeoff or landing, and most midair collisions happen near an airport in good weather. So perhaps the riskiest thing we can do is to practice touch and gos on a beautiful Sunday afternoon. Skip

Risk management involves a number of steps. First is identifying the risks. Second is assessing the risks which is where the risk matrix (likelihood vs. severity) fits. The matrix is a tool to guide you to identify which risks are significant enough to require a risk management plan. Traditionally, risk management plan strategies fall into four categories: Avoid, Mitigate, Transfer, Accept. Examples due to a risk of icing might be: Avoid - cancel the flight. Mitigate - delay, or choose a different route below the freezing level, or use a different airplane with FIKI capability. Transfer - take an airline flight. Accept - mission is critical, press on. Skip

I think you are probably right. I have never witnessed this personally, but it does seem possible given the way the RSA fuel injection system functions. The mixture control is at the servo and there is a couple of feet of hose between the servo and the flow divider and another foot or so of line to each injector. The engine would run on for quite some time after moving the mixture control to ICO if it had access to all the fuel in those lines. To prevent this, a spring loaded valve in the flow divider cuts off fuel to the injectors when regulated pressure drops after selecting ICO. There is still residual fuel in the lines to the injectors, and I guess it could eventually drain into the intake manifold through the intake tubes and then out the sniffle drain. Skip

Yep, Don. Found it had worn half way through a one inch diameter aluminum oil supply line on the museum B-25. Hard to believe, but nylon is tough stuff. Now the one I can’t quite figure out is the claim I’ve seen more than once here (it’s also in Don Maxwell’s external tubing article on his website) that gas will drip from the sniffle after a normal shutdown. If you shut down by pulling the mixture to ICO, where does enough gas come from to collect in the bottom of the intake manifold? Skip

An IO-360 should idle well at full rich at sea level if idle mixture is set correctly. Ground leaning increases combustion temps to aid lead scavenging and reduce plug fouling. If the roughness is typical Lycoming morning sickness caused by exhaust valve sticking it should only happen after a cold start. When the engine is warm, the valve will usually free up. There are backfires and afterfires - both can make a pop. Backfires are due to too lean a mixture which burns slowly so there is still fuel burning when an intake valve opens causing ignition of the mixture in the intake manifold. This can be caused by an induction air leak. Less common afterfires occur with a rich mixture that allows unburned fuel to accumulate in the exhaust and is ignited when an exhaust valve opens. This is what happens if you shut off the ignition at cruise power for a few seconds and turn it back on (don’t do that - the overpressure can damage the exhaust components). Skip

Not to be nit picky, but... The "internal resistance" of a battery is the series resistance. But you are correct in that all batteries have a self discharge rate -- some chemistries hold a charge longer than others. Skip

Not an FAA defined V-speed. Most efficient (by one measure) climb speed Vz = 1.32 x Vy. IntroducingVz.pdf

If I understand correctly, the radios came on while you were cranking. If the battery were weak and/or the starter drawing too much current, the bus voltage might drop enough during cranking to cause the the avionics bus relay to drop out and power up the avionics bus. As described, the fail safe design is that the relay must be energized to depower the avionics bus. Skip

Altitude hold works by "capturing" the static pressure at the engagement altitude and then adjusting altitude to maintain this pressure. To get a slow, continuous climb caused by a static pressure problem would require a small, constant offset from the "captured" pressure. This is pretty unlikely. I suppose that there might be a failure mode of the pressure transducer that would produce a constant offset voltage, but that wouldn't explain the trim. The description of the trim indication is exactly what would happen if you were to pull on the yoke while the autopilot was engaged. The pitch servo tries to push the nose down, but can't because you are holding pressure on the yoke and the autopilot tries to relieve the pitch servo pressure by commanding down trim. Since the airplane presumably has no non-autopilot control issues such as binding, the failure must be something within the autopilot that mimics this condition. I would begin troubleshooting by checking all vertical modes to determine if anything works correctly. I would check the pitch servo for bridle tension and clutch slipping. If all that doesn't find a problem then it might be the autopilot itself. Skip