PT20J

Are you saying you removed the cap and accessed the microswitches, or the large screw on the other side? The large screw adjusts the spring tension to set the calibration. https://www.knr-inc.com/shop-talk-articles.html?view=article&id=93&catid=25

Do you know if the problem is the diaphragm or the microswitch? These units have two microswitches. One is used for the gear and the other is for a flight timer or some other accessory that is often not installed. If the microswitch is bad, you might be able to just switch the landing gear circuit to the other switch.

My M20J had the marker beacon antenna mounted above the one piece belly. The DME and transponder antennas were mounted to the belly. Only the transponder antenna remains.

I don't know what the difference is but I doubt it has anything to do with the bus voltage. The voltage spec on switches is related to arcing which shouldn't be an issue at these low voltages.

According to the Lycoming power curves for an IO-360A, 90 rpm low (2610 instead of 2700) at sea level/ 59 deg F is 192 hp (loss of 8 hp). 1 hp = 33000 ft-lb/min. So, at 2700 lb gross weight, 8 hp would reduce the rate of climb of 8*33,000/2700 = 97.8 fpm.

Based on my research, I personally would not replace the NBS. 1. The 1000 hour recommendation seems to be based on a couple of failures of Plessey actuators and carried over to Eaton. This has never been a serious enough problem to warrant an AD. 2. The failure of an Eaton actuator (and recall of a particular range of serial numbers by Eaton) appears to be due to a particular lot of springs years ago. Those have likely been replaced or have failed by now if they are going to fail. 3. Most of the very few documented failures have been Plessey actuators, the most recent only a few hundred hours after spring replacement. If I had a Plessey actuator, I would consider spending the $10K or whatever the going rate is to replace it with an Eaton if I could find one. 4. Hours isn't really important -- it's cycles. But cycles are not tracked in single engine piston airplanes. According to Don Maxwell, the spring is rated for something like 20,000 cycles. So if you cycled the gear once an hour on average, that would be 20X the recommended replacement interval. 5. A new spring would have some risk because they are not in current production. People are going to have to dig out a 50 year old drawing and make a part that they likely have never made before. Maybe they are simple to manufacture and maybe there is some technique to it. Processes were often not as precisely documented in the age before everything was done on CAD. Who knows? There was some post to the effect that Mooney rejected a batch that didn't fit correctly. I have no first hand knowledge of that. Skip

Here's an interesting site that has historical maps showing areas where ADS-B out from aircraft reported degraded GPS navigation accuracy. www.gpsjam.org.

The IPC pdf has the following comment: S/N 24-0001 thru 24-1685 order 880013-505 (All earlier 14V) S/N 24-1686 thru 24-TBA order 880013-507 (later 14V and All 28V) I would contact Frank Crawford at Mooney and ask about the difference (he maintains the IPCs and wrote the comment). I'm pretty sure VEP made both of the switches. Frank might be willing to cross reverence the VEP part number for the -507 if the -505 won't work. fcrawford@mooney.com (830)792-2920

Define "tricky."

Yes. But you should be doing that anyway because extended idling below 1000 rpm is a leading cause of spark plug fouling since lower cylinder pressures allow more oil into the combustion chambers and lower CHTs impede lead scavenging. I usually keep it between 1000 and 1200 rpm except when necessary to slow down while taxiing.

I paid careful attention to the landing gear action in my 1994 M20J during some landing practice last evening. During extension, there is a "thud" when the gear locks down, but no noticeable movement of the floor. There is no similar thud and no noticeable floor movement when the gear retracts.

I checked my 1994 M20J. The Service Manual indicates that the annunciator should indicate low voltage when the bus voltage drops below 26.5V. I notice that there is some hysteresis in the annunciator: when reducing rpm, it begins to blink at about 950 rpm and 26.5V; when increasing rpm it will stop blinking at about 1100 rpm and 27.0V. Skip Edit: My alternator was new with the rebuilt engine so it has about 450 hours on it.

Let's start with the last comment. The important thing is that when trimmed for takeoff, the elevator should be in trail with the stabilizer. There are bungies in the elevator system so you have to wiggle it up and down a bit but the center point should be very near the in trail position. When it's set this way, note the position of the trim indicator on the console and that will be a good indication if the indicator is correct. When taking off a M20J, with the normal 15 deg takeoff flap setting, the smoothest way to do it is to apply approximately a 5 lb pull on the elevator during the takeoff roll and slowly release it as the airplane lifts off to establish a climb attitude of about 7 deg nose up. The airplane should be very nearly in trim. When raising the flaps the airplane wants to pitch up so you need to trim down. When you level off in cruise and accelerate, further nose down trim will be necessary. In my MSE, I end up with the trim indicator somewhere between the takeoff band and full down, but nowhere near full nose down. When slowing for landing with flaps, the trim indicator will be somewhere above the takeoff band. The first thing to check is that the trim indicator is set up right. If something has changed, that is most likely what has changed assuming that the airplane flies right. As a comparison, I made the following measurements on my MSE: Full down trim, the leading edge of the vertical stabilizer is tilted aft 5 deg from vertical and the elevator is about 10 deg trailing edge down. Full up trim, the leading edge of the vertical stabilizer is tilted 1 deg forward from vertical and the elevator is about 10 deg trailing edge up.

I have no idea what is the "best". But I assumed that Mooney might have. So, when I pulled my interior for avionics installation and to repair and paint all the plastic, I ripped out all the remaining fiberglass (I already had the aluminum/foam insulation on the side panels) and I ordered the material from Mooney through a MSC. The airplane is maybe slightly quieter (hard to tell) but it stays cooler in the summer and doesn't take much heat to warm the cabin in the winter. Mooney sells the material in rolls, (I forget the width) and it's expensive, so I spent some time figuring out how to cut out the pieces I needed from the minimum length of material. Mooney buys the aluminum/foam from one company and then has another put the adhesive backing on it and then they do a burn cert. The adhesive is interesting. You can lift it up and reposition it while installing, but if you let it set a bit it is impossible to remove without tearing up the foam. Skip

I measured it once many years ago when when gathering data for a flight simulator, but I don’t seem to have it any more. The way to do it as suggested by a flight test engineer is to roll from a 60 deg bank to an opposite 60 deg bank and use a stopwatch to time from 45 deg to 45 deg. I agree that 60 is probably more than necessary, but it is safest to start with too much. The last airplane I rolled was a friend’s T-6G and it needed about 45 which surprised me - I guessed 30. Skip

Is that 310 with the flat tires still tied down there west of the old Aero Trends hangar?

NACA report No. 772, August 1940, thoroughly explored the effect of mixture strength (including LOP) on BSFC, BHP, and CHT.

I was thinking the same thing. The stock Mooney has a slow roll rate (which is why the original Predator wing and shorter flaps and longer ailerons - Maxwells have since replaced it with a wing off a K) and is very slick as Ross notes. All airplanes drop the nose in an aileron roll, and to avoid picking up excessive speed at the end it’s necessary to begin the maneuver very nose high in an airplane with a slow roll rate. In a Mooney it’s probably something like 60 deg nose up (I don’t know because I’ve never tried it). I only mention this because someone’s gonna try it. Watch a video of Bob Hoover rolling the Shrike and notice how much he pitches before beginning to roll. Hoover was so smooth that he claimed he never exceeded 2 g’s during his energy management routine. Like Ross, I prefer aerobatics in a Decathlon. Skip

The GFC 500 seems to be the only currently viable new Mooney autopilot, but you are not going to like the price because it requires a G3X, G5 or GI 275 -- it won't work with an Aspen PFD. Unlike older autopilots, most of the autopilot software actually resides in the PFD which is why it requires Garmin displays. You could join the long line of others that have been waiting for the Bendix-King Aerocruze 100. It has been available any day now for years. Maybe someday it will happen.

Lead fouling is caused by rich mixtures (more lead in the cylinder) and low operating temperatures (poor lead scavenging which takes heat to initiate the chemical reaction). https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart-18-30071600.html Skip

BMP technique seems more useful in turbos as a way from going from ROP high power WOT to a lower LOP power without touching the throttle. In my little IO-360, the only time it would be applicable is at low altitudes, and when I cruise any distance, I’m high enough that mixture is not going to hurt anything. Some of the APS ideas like BMP and running tanks dry just don’t fit my operational philosophy of smooth flying. I flew a lot of Part 135 for years and we always strived to fly so that the pax couldn’t tell you changed anything. Not saying the APS guys were wrong; it’s just not how I fly. Skip

I don't believe that there is a BY plug for 3/4-20 leads. The approved BY plug for an IO-360 is an (U)REM37BY. (U if it is Tempest). According to SI 1042, you should only use long reach plugs (URHB37E) if the cylinders are marked with yellow paint between the spark plug hole and the rocker covers. You could change the ignition harness to 5/8-24 and then you could use all UREM37BY plugs which makes rotating simpler.

I never understood this fear of weighing thing. It weighs what it weighs. Suppose you weigh it and find out that it is 100 lbs heavier than the calculated W&B. That means there is some mistake in the calculations. If you don't trust the scales, reweigh using different scales. So, now you find out that you have been flying 100 lbs over gross for years. So, you can continue to do that. No one will ever know unless you have an accident. And it you have an accident, maybe it is because you are flying over gross.

Yes.

Sounds like a McCauley from the description. Can’t explain the difference in instructions.