PT20J

I use my dad's old hand-me-down monkey wrench -- much prized by steam locomotive engineers. Skip

Here's the letter from Aspen: Aspen Pro MAX Evolution 2000 and Evolution 2500 Systems Dear Valued Aspen Customers: Today, the FAA issued Airworthiness Directive (AD) 2020-16-08 effective August 17, 2020, regarding a potential reset event of Aspen Avionics' MAX series displays. Be advised, the FAA approved software v2.10.2 in March 2020 addressing the infrequent but potential reset issue of Evolution MAX series displays and we have successfully implemented this software change for affected customers. These design changes are defined in the 900-00003-001, Revision CC, EFD1000, and EFD500 Software Version 2.X installation manual, dated March 2020. Aspen Service Bulletin 2020-01 describes the v2.10.2 software update procedures. This AD only applies to Evolution 2000 MAX and Evolution 2500 MAX systems with software v2.10 or v2.10.1 AND if any of the required backup instruments (ASI, ATT, ALT) have been removed. This AD is not applicable to MAX displays that have been updated to software v2.10.2 or any legacy Aspen Avionics displays. Please contact your Aspen Authorized Dealer if you have not yet updated your MAX displays to software v2.10.2.

Well, the original price in the 1992 SB is listed at $1750, so it has less than doubled in 28 years. Careful examination of the IPC will show that lower tube part number 340117-119 in earlier models has a .035" wall thickness and was changed to part number 340155-135 with a .049" wall thickness at S/N 24-1686 which is the first S/N eligible for the gross weight increase. Skip

No, the point is that they had a great product and had difficulty with newer technology. That's very common. Sometimes companies recover and sometimes they don't. HP made oscilloscopes but the triggering circuit was really bad. An engineer left HP and started Tektronix with an idea for a better triggering circuit. Tek scopes were so much better that HP got out of the oscilloscope business for a few years. When they came back they had a competitive product. So, you have to keep looking at the current product offerings and not live in the past.

Reviewing this thread, there's a lot of good info, but I don't think we answered your question. Let's see if I can break it down: 1. The purpose of the low voltage annunciation is to alert you that the alternator is not charging the battery. It is set to about 12.5 volts so that it should flash when you are running on battery power only. Thus, the indications you mention are normal. 2. The way to tell the charge state of the battery is by measuring the voltage at the terminals with no load on the battery. The 11.7 volts you measured seems low, but that's with the master on so there is some load and thus you can't really tell anything from that measurement. 3. The only way to tell for certain if the battery needs replacing is to do a capacity test. Most people just wait until it is so worn out that the starter is sluggish. That may be OK if you only fly VFR in uncongested airspace and don't mind the inconvenience of getting stranded at a strange airport. But, if you really need the battery to run stuff for an hour or so after an alternator failure, you should do a capacity test at least annually. Skip

Gill makes great flooded cell batteries. Its sealed batteries weren't so great. I think they quit making them until they re-engineered them. Maybe they are good now. Champion had problems with resistors in its spark plugs. They are now redesigned and are probably just as good as Tempest. Tempest fine wires had problems shedding electrodes. I'm thinking about buying fine wires when I install a Surefly mag. Should I buy Tempest? Things change. Companies learn. Products improve. But people have long memories when a bad product cost them money. Skip

Except for the rare case where an ICA includes aircraft limitations changes, ICAs are like service bulletins: optional for part 91 operations. Most IAs don't bother with them at annual because CBs are always complaining about how much the inspection costs . However, just like service bulletins, it's a good idea for the owner to read the ICAs for installed equipment and decide which are important. Lubricating the speed brakes is one that commonly gets ignored Skip

If it hasn't been flying, has the engine been pickled? If not, the big concern would be internal corrosion. The cylinders could be pitted but the biggest risk is the camshaft which you cannot inspect without some disassembly. As you noted, the engine is beyond the Lycoming 12 year TBO. I would also be very concerned about the airframe and avionics. Mechanical and electrical components do not like to sit. Electrolytic capacitors in radios go bad. Bearings deteriorate from moisture, etc. I volunteer at a local museum and a lot of the airplanes fly less than 10 hours per year. They are all hangared. We usually find stuff that needs fixing at every annual. The mechanic says he'll never be out of work since they seem to break just sitting there. If it were me, I'd look for another airplane. But it this one is really the one you want, I would get a very thorough prepurchase inspection including oil analysis and borescoping the cylinders by someone that knows Mooneys well and knows what to look for, and I would nit pick every little discrepancy (realizing that you won't find them all) and negotiate a deep discount. I would also go into it with a healthy cash reserve tucked away in case it needs an engine replacement and other expensive work. Skip

The aircraft voltage regulator is inop when the master and alt switches are off. The Concord Manual indicates that 11.7 volts is fully discharged if there is no load on the battery. I would turn off the master and verify the open circuit voltage with a digital multimeter at the battery terminals, but it probably needs replacement. Battery life is greatly dependent on how the battery is treated, so claims of x years of service are really meaningless. Things that shorten battery life are: Overcharging (voltage regulator set too high) which boils off electrolyte, and deeply discharging without recharging immediately which causes sulfation. Battery life is extended by keeping it topped off with a trickle charger. Skip

The only way to know the condition for certain is to do a capacity test. Documentation is on the Concord website. Skip

Hey, all you airline guys -- what color are your panel lights?

The SB is indeed optional under part 91. Unless you have an included serial number and wish to change the gear speed limitation, you can ignore it. If you have a model earlier than a M20J, the SB does not apply and there is no way to change the gear speed without getting the FAA involved because the gear speed is a limitation listed in the TCDS. If you look at the TCDS for the M20J, you will note that the SB is referenced. Note also that the SB is marked FAA Approved. That's because in order to get FAA approval of the TCDS change, you can bet that Mooney sent a raft of engineering backup to the FAA. Skip

Because it's a change to an operating limitation which has to be approved by the FAA.

Well, since you are lurking about.... I took a look at the Aspen patent (attached) and thought over the calibration procedure. The calibration requires straight and level flight at two airspeeds (cruise and approach) clean, and at approach airspeed with gear and flaps down. Tolerances are pretty tight: airspeed constant to within 3 KIAS. vertical speed no more than 100 fpm, pitch change no more than one degree, roll change of no more than two degrees. (Side note: in smooth air, I was amazed at how well my 45-year-old design KAP 150 autopilot did that). The object of the clean tests appears to be to determine the lift curve and the third test is to determine the lift curve offset with gear and flaps down (the lift curve slope would be assumed to be the same in both configurations). One of the primary objectives of the algorithm appears to be to avoid the necessity for supplying the aircraft weight during normal operation. I can see why this would be beneficial as having to enter the weight would be error prone and make the system more complex to use than competing systems. The algorithm gets the gross weight stall speeds from the airspeed data entered in IAS CONFIG B. In this case, Vs is 62 KIAS and Vso is 58 KIAS from the POH. Assuming that the stall warning speed is 5 kts higher (which measurement shows to be the case), this gives stall warning speeds of 67 KIAS clean and 63 KIAS dirty at 2900 lb. Adjusting for the flight weight of 2321 lbs decreases these speeds by a factor of SQRT(2321/2900) = 0.895 or 59.9 KIAS clean and 56.4 KIAS dirty. However, during the pre-calibration flight test, I measured stall warning speeds of 56 KIAS clean and 52 KIAS dirty which are about 4 kts slower than the calculated speeds. (Aspen has you measure the stall warning speeds rather than the actual stall speed. This makes sense to me since the lift curve is highly non-linear around stall. It does introduce a source of error if the stall warning is not set correctly, but I checked mine and it is pretty close to 5 knots above stall in all configurations). It seems pretty clear that the purpose of the bias values is to correct for non-standard stall speeds. Mine are only off about 4 kts, but maybe that's enough to mess it up. I'll wait and see what Aspen comes back with. Skip WO2016164624A1.pdf

It was only an approved change to the operating limitations starting with M20J S/N 24-0378. SB M20-209 allows you to change the placard for earlier M20Js. I'm not aware that Mooney ever extended the change to the F or earlier. I think the real strain of the gear actuator is during retraction and the lower the airspeed the better. I know that the manual gear certainly takes more force to retract as the speed increases. Skip

I checked all the calibration info per the manual and it was correct. I only changed the weights because they were different for my calibration flight than the calibration after installation. There are no mods on my aircraft and it stalls at the book speeds and I checked that the stall warning is calibrated within spec. The software should be up to date as it was checked last January when the ADS-B unlock was installed. I sent Aspen tech support my test data and asked about bias values. The reply was: The “In-Flight Pre AOA Calibration Check” and bias numbers are only used for aircraft with mods that are not accounted for in the AFM, like some types of VGs and STOL kits or with conditions specified in the Limitations section of the instructions. I’ll send this over to engineering and see what they say about using the bias numbers. Maybe they can pickup on what is causing the pointer to read so high. Skip

I'm curious about other's experience with the Aspen AOA indicator. Mine, in a 1994 M20J, was installed for the previous owner. It has never indicated properly -- a normal approach ends up with the pointers near or in the cross hatch area where they are supposed to be when the stall warning sounds. I checked the configuration info and re-flew the calibration procedure yesterday and it's still about the same. I sent all the data to Aspen tech support which sent it to engineering and I'm waiting for a response. In the meantime, has anyone got one to work right, and if so did you need to add bias values or tweak anything? Skip

Not much to it as Mooney uses standard Cleveland wheels and brakes. It's a good idea to let the air out of the tube before removing the axle nut just to be safe. Be sure to torque the wheel bolts properly and don't pinch the tube. And don't get the bearing preload too tight when putting it back together. The only Mooney-specific thing I can think of is on planes with the inner gear doors you need to keep track of the washer and spacer placement to preserve the gear door alignment. Everything is covered in the Service Manual. Skip

The factory hasn't been formally revising the manuals for out of production aircraft for years. As Steve Rue explained it to me a while back, to avoid a formal revision which involves the FAA, they have been collecting changes in comments embedded in the pdf files of the last released version. If you print out a copy, be sure you update it with all the changes embedded in the electronic files. Fortunately, there aren't that many, but there are some. Skip

No apology necessary. I wasn’t aware of that procedure in the manual for your airplane, and it’s a strange one. I think if you use that technique, you will have to use the flooded start procedure to get it started.

They are backordered from Surefly so they won't ship until mid-August Skip

This is the same information that would be included in a POH/AFM for an aircraft built after 1975. Note that this is not an FAA-approved document (only the Limitations section of the POH/AFM is FAA approved). If missing, a replacement might be available from Mooney, but if they wanted to charge me much to reproduce it I would not bother because there really isn't much value to it. The original weight and balance is most certainly out of date. The only W&B that counts is the last one; no one cares about what went before except to check for possible math errors which are irrelevant once you weigh it. The equipment list might be nice, but it's probably way out of date also. The loading stations and envelope information are in the TCDS and you can reproduce the graph from that information on a piece of graph paper or just enter it in Foreflight or a smartphone app. Skip

Not sure what you mean by w&b manual. There are three items of interest. First is a weight and balance computation. If that is unavailable, one can be easily created by using the procedure in the Service and Maintenance Manual. The second is the equipment list, which I don't believe is required to be updated (and most aren't), but it can be really handy to know the particulars all the installed components when researching applicable ADs. The third item is the loading graph and stations for fuel, seats, baggage, etc. This information is generally in the POH/AFM for newer airplanes. If you don't have it, the information can be found in the TCDS. Skip

I didn't know that Mooney left the hot start procedure out of some manuals. Don't know why as it's been the same forever on all RSA fuel injected Lycomings. It might be best to review the theory. Gasoline will only combust over a fairly narrow range of fuel/air ratios. When the engine is running, the fuel injection system controls this. Starting is more difficult. Too much fuel (relative to air) and it won't start. Too little fuel and it won't start. How to get it right? For the cold start we prime which leads to a slightly rich (too much fuel) condition. As we crank, the fuel gets used up and eventually the mixture is within the ignition range and it starts. (It's really a bit more complicated than this as the fuel has to vaporize and mix with the air to form a combustible mixture which is why it's harder to start when it's really cold). Why are hot starts more challenging? When the engine shuts down, a valve in the flow divider shuts off fuel to the injectors to give a clean shut down. Still though, some fuel remains in the lines. If you restart within a few minutes, there is enough fuel in the lines to get the engine to start. If you wait longer, the fuel evaporates and you will need to prime. How long between not needing to prime and needing to prime is dependent on both time and ambient temperature. Only experience will guide you here. Why does it work to run the engine to 1000 rpm and shut down and then restart when still hot without touching anything? With a hot start, there is an unknown amount of fuel in the lines to the injectors. Immediately after the shutdown, there is some. A day later there is none. In between -- who knows? So, the biggest problem is introducing too much air. Most people open the throttle too much. Try shutting down at 1000 rpm and then close the throttle. Notice how little it is open. Skip