PT20J

No. But as @jetdriven noted, the tach is required equipment under FAR. So, technically the aircraft is unairworthy without it But, if the FAA determines (this is where the FSDO has latitude) that the flight can safely be conducted to a place where repairs can be made, it can issue a special flight permit (aka ferry permit). https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/sp_flt_permit/

My Aspen PFD is similar. The specification is >30 minutes and I've tested it twice in two years and it runs about 42-45 minutes. The best way to test it is to put it on battery and time it during a flight. On the ground (actually if the airspeed is <60) it will shut down anytime ship's power is not supplied. Having made my living as an engineer, I like to test everything. So whenever I get a new backup program for my computer, the first thing I do is make sure I can restore from the backup. I just had my Concord battery capacity tested. Cost me an hour of labor ($120) at the only shop nearby that had the tester for a 28V battery. I'm wondering how many of us that have avionics with battery backups ever test them? If you have a bunch of instruments, each with it's own battery, and the electrical system fails, at some point all the little batteries are going start timing out -- I'd just like an idea of when and in what order. I live in the mountainous west and may not be in a position to land in half an hour when it happens. My question about the G5 battery indicator is driven by my experience that battery life indicators on cellphones, cameras, laptops and the like seem to be pretty imprecise. I've had them go from "full charge" to "darn near dead" pretty quickly. Skip

Or maybe it was Garmin, or a KI 258? I listened to the recording. The pilot was evidently having trouble navigating, first low and left of the localizer and then right of the localizer. I have no idea why and will not speculate, but the pilot never mentioned an equipment problem and indicated that he was correcting back on course when queried by the controller. After the first deviation, a different (supervisor?) controller took over communications and instructed the pilot to fly heading 160 and climb to 5000'. The pilot acknowledged the altitude, but not the heading which is why the controller repeated the instruction several times asking for confirmation that the pilot would fly 160. The pilot never did acknowledge the heading and may not have initiated the climb because the controller then issued a simplified instruction to maintain altitude and fly south and subsequently he instructed the pilot to just fly straight and level. Somewhere around that time it appears that control was lost. It's very sad and unfortunate and we will never know for sure exactly what happened in the cockpit. For me, the takeaway is to never try to salvage an approach. If everything isn't right, go missed early and get some altitude between you and the ground. Skip

The King autopilots have internal checks on the trim system and will disconnect in cases of uncommanded trim operation. Here are the two autopilot scenarios that I’ve seen most often get people in trouble. Overriding the autopilot 1. The autopilot is set up incorrectly and doesn’t capture altitude or glideslope or (this is really common) without altitude preselect, the pilot gets distracted and climbs through assigned altitude. 2. Pilot reverts to primary training (fly the airplane) and overpowers the autopilot without engaging CWS or disconnecting the autopilot. 3. The autopilot trims against the pilot’s inputs, increasing stick forces. 4. To alleviate the rapidly increasing stick forces, the pilot disengages the autopilot and away we go! Autopilot in pitch hold, VS hold or ALT hold with insufficient power available. 1. Pilot reduces power to slow down in ALT hold and gets distracted. 2. Autopilot continues to pitch and trim up until airplane either stalls or autopilot disconnects at low airspeed with nose up trim. 3. Same thing in a climb with a NA engine especially in VS hold. Skip

Cables break if not kept lubricated, so check that first as an easy fix. I‘d unscrew it at the tach and pull the cable core out to check. You don’t need the tach to safely operate the engine - just leave the prop set to high rpm and set appropriate MAP. Ferry permits are at discretion of the local FSDO but an inop tach shouldn’t be a problem. Skip

Per attached: Counterweight Applications: On 4 cylinder models – the #6 as the 4th suffix character indicates one sixth and one eighth order counterweights. SSP-110-1 Certificated Engines.pdf Skip

I think you are right. I thought the override was on all models after Mooney ditched the squat switch for the airspeed switch, but I looked at a F owners manual and don’t see it mentioned. Perhaps some other F owners can clarify if it was ever on the F, or got added at the J.

A safer option is to press the little red button next to the gear switch to override the airspeed switch.

According to the Service Manual for my J, the factory used rivets instead of the two right side fuselage screws on some later models. I don’t know if this applies to the K or not, but if you don’t have screws, you will have to drill out the two rivets. Skip

Has anyone run a G5 all the way down on its internal battery? Did the "time remaining" displayed on the screen match reality? How long did it actually last? I've never had a laptop that accurately predicted battery life and so I'm wondering if the aircraft instruments are any better. Skip

According to the service manual section 32-60-03, the switch should be adjusted for 60 +/- 5 kts. When it was replaced, the shop should have calibrated it per the service manual procedure. Skip

I didn’t try it but from the way it was acting, I think it would fly it into a stall. I know that the S-TEC on the early SR-22s would. Skip

Today I tried an experiment in my 1994 M20J with a KAP 150 autopilot. I set the autopilot on heading hold and altitude hold in cruise and reduced power. The 40 year old autopilot (KAP/KFC 150 was introduced in 1980 according to the installation manual) held heading and altitude at 65 KIAS. Roll response was a little sluggish but acceptable if I added enough right rudder to keep the ball centered. The airplane was in trim when I disconnected the autopilot. Skip

I think that's a great idea. And as you noted, the FAA doesn't have the same view of logbooks that we do. For example, suppose an owner had an annual inspection performed thirteen months ago and none since, and that inspection was recorded on a single page in the aircraft logbook. As far as the FAA is concerned, the aircraft is unairworthy until it passes a new annual inspection. So, why would it care about the last one that is no longer valid? Water under the bridge. Per 91.417, you could legally rip that page out of the logbook and throw it away -- the FAA doesn't care. Skip

Agreed I was really just trying to see how far I could get at the system component level, but the exercise quickly pointed out to me how little I know -- or could find out -- about the internals of these boxes. Skip

Avionics used to be simple. Every radio or instrument performed essentially one function and there was minimal interaction between devices. Failures were pretty easy to detect, and their effects reasonably obvious. But, as my recent GTX 345 AHRS failure has shown, that's no longer the case. The AHRS acted squirrelly in both pitch and bank without any warning indication on the iPad running ForeFlight. Garmin Pilot did put up a DEGRADED warning long after I would have lost control of the airplane. Garmin tells me the AHRS system in the GTX 345 is the same used in many of their primary flight displays. I started working on a simplified Failure Modes and Effects Analysis (FMEA) for my set up. This requires several steps: 1. Identify all possible failures modes 2. Identify how each failure mode can be detected 3. Identify the effects of each failure mode 4. Design a mitigation plan for each failure mode The problem I had with doing this was identifying the failure modes for complex equipment, and knowing how to detect that a failure has occurred. Consider something complex like a PFD which displays primary instruments and navigation information. It's easy to know you have a problem if you get a big red X. But will all failures cause this indication? Who knows? Without understanding the internals, it's hard to tell what failures there might be or how you would come to find out that something has failed. The manufacturers aren't a lot of help. I called Garmin and asked how loss of the external GPS signal would affect the accuracy of the internal AHRS in the GTX 345. The tech support person didn't know and put me on hold to ask an engineer. The answer was, "It shouldn't have an effect." That's not entirely comforting. I think what saves us from falling victim to a probable host of subtle and undocumented failure modes is that modern avionics are pretty reliable. I have reasonable backups and don't worry too much about it. But, I'm retired, try not to have to be anywhere on a strict schedule, fly a NA M20J and avoid bad weather minimizing (but not completely eliminating) my IMC exposure. If I had a turbocharged airplane with FIKI and flew in the weather a lot, I would think about this more carefully -- a lot more carefully. Skip

ELTs are great, but nothing beats calling that airliner passing overhead.

The original J was the same as the F with ailerons going all the way to the tips. I think it was around 1981 that the plastic wing tips and enclosed balance weight were incorporated. The other thing that doesn't help is the chord. It takes a certain area to get the effectiveness desired. A lot of span got used for the flaps so that makes it necessary to increase chord to get the required area. I believe that the hinge moment varies linearly with span and as the square of the chord. Skip

I think this will clear up most 337 confusion: https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43.9-1G.pdf Skip

BEVELED AILERONS (again): Mooney introduced beveled ailerons in the 1960s and they may have been added to reduce hinge moments (stick forces) for the PC servos. Thickening a control surface and beveling the trailing edge is a method for improving aerodynamic balance and reducing stick forces used ever since the later P-51s. For some time, I've been trying to understand exactly how they do this. I thought I understood it a while back, but was never completely satisfied. I finally found a good explanation in Airplane Stability and Control by Abzug and Larrabee. The idea goes like this: Suppose an aileron is deflected down (to raise a wing). The protrusion into the airstream thins the boundary layer on the bottom and thickens the boundary layer on the top. The thinner boundary layer tends to follow the surface contour better, so when the air flowing along the bottom gets to the trailing edge it wants to follow the bevel and deflect upward. Curving the airflow requires a pressure change -- in this case a lowering pressure at the bottom of the trailing edge. The thicker boundary layer along the top surface doesn't follow the bevel well so there is a differential pressure effect that tends to pull the aileron down which is in the desired direction. NACA report 927 (referenced by Abzug and Larrabee) quantifies the effect: Skip

The way insurance companies make money is on what Warren Buffett calls “float.” It’s the timing difference between when premiums are collected and claims are paid. The companies get to invest money that isn’t theirs to keep (it will have to be paid out in claims at some future date). But, they get to keep the investment income. When investment returns are low and losses are high, premiums will rise. It’s basic business economics. Competition ensures that the converse is also true. Skip

Pretty interesting how close the three quotes are for the carriers that would quote the risk.

Both by J’s — one manual and one electric— would cruise @ 70% with the cowl flaps closed at peak EGT with hottest cylinder 380 F or less. Manual one had flat left cowl flap rigged slightly open when closed to make room for the tubes, and electric one has the bulge.

For a K maybe. But for a J, I think they only increase my long-term maintenance costs. .

Actually, according to the BK Installation manual, it was developed in 1980. Mine flies great for 40 year old technology. Skip