Vance Harral

If you read back through this thread, you'll see that @Gert did exactly that for his own purposes, and tried to help out other owners by making parts available at https://avunlimited.co/product/mooney-landing-gear-shock-disk/ There was some predictable skepticism about the degree to which this qualified as OPP, but I think most of the group here was enthusiastic and supportive. Response elsewhere (Facebook posts) was less kind. The parts on that web site have been listed as "out of stock" for years, and Gert hasn't visited this board in 3 years. I don't know what all may have gone on in the interim, but it renders me pessimistic that there's an OPP solution for the masses. Only, perhaps, one-off installations by individuals who stay quiet about it.

Correct. But the fix for that costs pennies in the way of O-rings, hydraulic fluid, and air; and it doesn't require special tools most shops don't have. Mooney "pucks" were a fine idea in their time, but the current state of the parts and service market makes them undesirable. Bonanza/Commanche/etc. owners aren't contemplating whether they should jack their aircraft up off the gear after every flight. Buy them now. They have a decent shelf life when stored indoors, uninstalled; and the price and availability are only going to get worse between now and when you need them.

Do you have a digital OAT probe system connected to your Garmin avionics, that along with pressure altitude allows the computation of true airspeed? Calculation of winds aloft requires knowing true airspeed in addition to GPS-derived ground speed. No digitally connected OAT probe, no winds aloft data.

This idea of jacking up your airplane while in the hangar has been discussed before, and I even know of one Mooney operator at my local airport who does it. But I find it ridiculous, and a good example of inappropriately de-emphasizing a significant risk to address a much less interesting/important risk. The risk of a Mooney falling off the jacks is pretty small if it's only done once per annual. It's significantly higher if you're doing it literally every time you fly the airplane. The cost of the airplane falling off the jacks would be 50x the cost of a set of gear pucks (for the average Mooney), not to mention weeks/months of repair time (or infinite if the aircraft is totaled). It requires extra equipment to maintain, extra procedures, and extra caution telling everyone who comes by your hangar to be careful and not lean on the airplane. On a lesser note, it makes you the laughing stock of the airport: "Haha... I guess those Mooneys are OK airplanes. But the landing gear design is so dumb that owners jack up their airplanes in the hangar". Overall, just a really bad idea. To each their own, but if this really became de rigueur for Mooney owners, I'd sell the airplane.

The OEM CHT probe on that vintage of Mooney is not a thermocouple. It's a thermistor, which works on a different principle, and uses the engine itself as the ground connection (hence why there is only one wire to the probe). CHT probes from JPI and Insight are 2-wire thermocouples, they simply don't work with the original CHT gauge in the Garwin cluster. That's the whole reason "piggyback" thermocouple probes are used when a non-primary engine monitor is installed in an aircraft which needs to retain the OEM CHT probe. It allows the original thermistor to stay installed to drive the original gauge. This is the CHT probe that fits our 1976 M20F: https://www.aircraftspruce.com/catalog/inpages/rochcht.php. Older M20F models may use the same one, but double-check your parts manual

This is a real concern, but like much of aviation lore, I think it's oversold vs. other concerns. Story time: we bought our M20F in 2004, with the Hartzell HC-C2YK-1BF common to that vintage. The prop was installed in 1991, and had never been overhauled at the time of our purchase. In the past 21 years we've had it overhauled twice, including the dreaded blade profiling. Once in 2006 when we installed a new "B" suffix hub to eliminate the prop AD. Again in 2016 because it was slinging grease, and the well-recommended local shop that allowed us to avoid shipping to other parts of the country declined to IRAN a prop with a little over a decade since the last overhaul. We're now at 34 years and counting on this set of prop blades, with two overhauls, and perhaps a third coming up in the next few years if we follow suit. The last time we had the prop overhauled, I asked the shop how many re-profiles they thought the blades had left in them. The answer was "definitely one more, likely two, maybe three if your really lucky". So we're on track to get 45+ years out of this set of blades (and I might be dead by then), despite ignoring advice to "never get a full overhaul if you don't absolutely have to". If we'd had the prop overhauled every 6 years as the manufacturer recommends, we might be at limits on the blades now; but maybe not - a competent shop only removes the minimum material required to re-establish the profile, and the less operational time on the prop (which correlates somewhat with calendar time), the less material removed. But even if we were forced into a new set of blades today, that would amortize the cost over 34 years, which is longer than most people own an airplane in the first place. Looks like our F7666 blades retail for about $9K apiece these days, $18K for a set. Nobody wants to write a check for $18K, of course; but in our case that would work out to about $500/year. Not exactly break-the-bank money in terms of multi-decade aircraft expense planning. None of this is to say that IRAN-instead-of-overhaul is a bad idea, and I acknowledge there are probably some incompetent shops out there that take way more material off a blade during overhaul than is necessary. But re-profiling is done for a reason, as are other operations required in a full overhaul, and those things do actually have nonzero value. Equally important, understand that if you have a prop that hasn't had been completely overhauled in a long time, a subset of prop shops - including some good ones - simply aren't going to IRAN it for "policy reasons" (that was the chief driver of our 2nd overhaul - the local shop was really convenient, competitively priced, and well-regarded, but they just weren't going to IRAN a 10-year old prop). There are plenty of shops with more liberal policies, of course, but they may not be in your local area and/or have the best rates, so that complicates the decision making. Bottom line: sure, get an IRAN and avoid profiling if you can, you won't get any criticism from me. But blade profiling is not the only concern, and it's not dumb to opt for a full overhaul.

Yes. The approved model list is available at https://www.garmin.com/en-US/p/604257/#additional. The "201" is, in type certificate terminology, a Mooney M20J model.

I applaud the concept of personal minimums. But when I give my students the speech about them, I treat them like grownups, and explain that reality often makes it difficult to employ the concept the way it's written in the books. In fantasy land, one sets personal minimums for weather, pilot rest, and so forth, that start out very conservative, and are gradually stepped down as the pilot gains experience. This fantasy can actually work OK in reality if your life moves slowly, the frequency at which you fly changes smoothly, and the weather where you live is broadly varied. In reality, most of my students experience sporadic patterns. For the pilot, it's common to do a lot of flying in a short time, then have long layoffs when money or life work load gets in the way. Weather-wise, where I live, winds tend to be either mostly calm, or gusting 20+ with shear; and ceilings are either very high or very low. So this idea that you gradually push your minimums down (and up) with experience and currency, just doesn't work out in practice for me and my kin. Two specific examples that are common in my area illustrate the point. First, the idea that you can do something like step up your crosswind tolerance in increments by first flying on a day with 5 knots crosswind, then soon thereafter 7, then soon thereafter 10, and so on, is laughable - that just doesn't happen around here. The reality is that you have to set your sights directly on 15G25, and go out with an instructor on those days until you're willing to accept that level of risk by yourself (and we don't lie to ourselves - a 15G25 crosswind always adds risk to takeoff and landing no matter how comfortable and proficient you are). With regard to IFR minimums, there's very little flyable IMC on the front range of the Rockies where I live. The clouds almost always have ice in the winter, and convective activity in the summer, and they're rarely within 2000' of the ground. So you're not going to "ease down" your approach minimums from 1500' AGL to 1000' to 700' and so on. You practice those ILS/LPV's under the hood to 200' AGL as if your life depended on it (because it does). Then you go out on one of those rare flyable IMC days and shoot a low approach for real. People with real life work/family schedules around here actually get to fly IMC a couple of times a year, if they're lucky. But if you make it work, it becomes reasonable to take that trip to the coast where benign IMC is more common. In the end, I've come to feel the same way as @bigmo about it. I actually care less about the theoretical concept of holistic personal minimums for a complete flight, than I do about "outs". I tell my students it's OK to take off if they judge it reasonable to take off from the airport they're already sitting at, and if they can reasonably expect to return right back to that airport. That keeps them reasonably safe for the first 10 minutes of the flight. Everything after that is dynamic: if you don't like the winds at your destination (maybe the look of them while 100 miles away, or maybe an actual aborted approach when you get there), can you find winds that are less and/or more aligned with a runway somewhere else? Do you have the fuel to get there? If IMC, where is the nearest VFR, or at least the nearest 1000' ceiling? These things need to be re-assessed several times per hour while enroute, and - this is critical - you need to be fully willing to wind up somewhere other than your original destination, even if you have to pee in a bottle on the way there. I've come to feel that some of the most important items in my safety arsenal are a credit card, toothbrush, change of underwear, and my work-over-VPN laptop in my flight bag. Having that stuff with me on every flight makes it much easier to divert somewhere with favorable conditions and wait things out. It turns out to be really rare to actually do this. But it's only once I developed the mindset, that I began to truly feel like I was correctly managing risk while traveling GA.

FAA: YoU mUsT rEmOvE eVeN tHe SlIgHtEsT tRaCe Of FrOsT fRoM tHe WiNgS Aircraft designers, paint shops, and mechanics: [hits bong], "Let's permanently install 10 square feet of rough skateboard tape on the wing roots" Intended tounge-in-cheek, of course, but it makes one think...

While this is reasonable advice, I'm pleased to say the lead time on tank reseals isn't quite as bad as people seem to think, unless you're simply unwilling to have it done anywhere other than Weep No More in Willmar. Dmax is doing a strip-and-reseal on our airplane starting next week, via an appointment we booked in December; and this thread details a good experience by a Mooney owner at Wet Wingologists, who worked him in on one month's notice. Not disputing that Weep No More is the defacto standard, king of the hill and all that. But there are other choices with similar equipment, reputations and warranties, and much shorter lead times.

Hard to believe it's been almost 5 years since the beginning of this thread. Our partnership has been using the original silicone mat purchased by Paul the entire time, with no issues. My PIREP below should be taken with a grain of salt, though, as our paint was terrible 5 years ago, and remains terrible today. We're cheap that way. The mat does appear to wrinkle just a little if you spill more than a drop or two of 100LL on it, and I was originally concerned this meant the 100LL was attacking the material and would eventually degrade it. But if you simply wait for the fuel drips to evaporate, the mat goes back to its original shape, and there is no evidence of the material breaking down over the years. I've stopped worrying about it. Note that I have no data on G100UL, as we don't fly anywhere it's available at this time. I do wish the mat was just a little longer on the long side, because with the hole for the fuel port cut as close as is reasonable to one edge, it doesn't quite hang over the leading edge of the wing when placed. This means that while fueling, the fuel hose still rubs directly on the leading edge of the wing, unless you specifically support it with a second hand. But the hose itself is rubber (or some rubber-like compound), and seems unlikely to damage paint, even if you have a nice paint job. The mat definitely protects the wing against accidental dings with the fuel nozzle itself. My favorite thing about the mat is just that it provides a place to set the Shaw cap (with all its scrapey appendages) while fueling. I no longer worry about it sliding off in a breeze or after being bumped, and further scraping up our dime store paint job. Worth it for that alone. As for Paul, I've visited with him recently, and he's well as you might expect. I helped him get a commercial certificate, CFI, and multi rating over the past few years. He recently sold his 252, and is on to other flying adventures, with two taildraggers in his hangar. He's actively using his certificates to teach and ferry airplanes, and I suspect he'll always be involved with the Mooney community, despite (for now) not being a Mooney owner.

Yes, and this same problem impacts pig farms, gun ranges, racetracks, and the like. I've been talking with friends about this a lot lately due to similar attacks on airports/operators in our own metro area. The bottom line is that, for better or worse, a large contingent of the population wants to live (and work) just far enough outside downtown to be "country", but not so far that it's more than a short drive to the grocery store, the doctor, etc. The sweet spot where you can do that spreads out every 5-10 years in any town or city that's not actively dying. So until the population collapses and/or literally all the land in the country is developed, airports and things like them are always, eventually going to be at risk from suburbanites. To keep your airport, you've got to convince the population growing around it that it benefits them, at least indirectly. The good news is, that's easier to do that with an airport than it is with a racetrack or gun range. The bad news is, as a group, pilots are pretty terrible at it. Far too much time and energy is wasted on pointless whining that, "The airport was here first". The reason this argument is dumb is that it's easily defeated - the pendulum will swing as soon as some reasonably intelligent person argues, "Yes, we agree the airport was here first, but the majority of our citizens don't care. Just because our community wanted an airport in the 1950s doesn't mean we want one now. Let's talk about the future, not the past, and that future is best for our citizens if the airport is closed." If you want to beat that, you've got to focus on why the airport benefits the town, not on childish prior possession arguments that just enrage the public and provide fodder for politicians.

Below are screen shots of the Brittain installation manual for the various autopilot systems. Assuming your airplane is in the listed serial number set, the pages I've pasted have part numbers for the aileron, rudder, and elevator servos, respectively. As you probably know, Brittain is no longer in business, and to my knowledge no one is officially producing parts or overhauling servos. You'll have to look for salvage parts, a new-old-stock "barn find", or mount a repair campaign you and your A&P are legally comfortable with.

I live in the Denver Metro area and trek down to the Springs several times a year to go to the Airplane Restaurant for $100 hamburgers. We download and keep our engine monitor data, so I've got plenty of info on this. I went back 3 years and tried to find the absolute hottest day on which I or one of my partners had a recorded flight, correlating temps from https://www.wunderground.com/. The plot below is from July 11, 2023, when the high at KBJC (elevation 5673') was 95 degrees F. It's a long flight, and while we didn't have altitude recording at the time, it's essentially guaranteed by the length of the flight that the climb out was to 3000' AGL or higher. I'm not claiming the flight departed at the hottest point of the day, but it was obviously hot all day long. Hottest CHT in the initial climb peaks at 389F before quickly settling down at level-off. A later climb at higher altitude gets right to 400, again before quickly settling down. I also pulled the raw data from the CSV files over the past two years and sorted it. The highest CHT we've ever recorded on any day under any conditions in those two years is 413F. We've had all-cylinder CHT monitoring since 2006, and in all that time I've never seen anything remotely approaching 450. If you're confident your instrumentation is good and all your baffling is pristine, then the only thing I can think of is you're developing more power than stock, and/or your cylinders run hot (are they chrome perchance?)

I'm sure you're not, but either your instrumentation or your engine or your baffling is amiss somehow. There's no way a stock M20F departing from a Colorado airport should have any cylinder at 450F during a Vy climb, regardless of atmospheric conditions or where the mixture is set. On the very warmest days in summer, our engine might be a few degrees over 400, briefly. I've never seen anything remotely close to the factory redline of 460 in our airplane, or other E/F models I've flown in around here, for 20+ years.

Nah, not with a correctly functioning engine at high DA. That chart I posted shows the effect of CHT with leaning, it changes by about 10C (roughly 20F) across the "max power" band of mixture settings. A difference of 20 degrees CHT during initial climbout isn't going to destroy a correctly functioning Lycoming, particularly not on departure from a high DA airport in a normally aspirated airplane where you're making considerably less than the full 200hp. If your stock M20F hits 450F CHT during climb out from a 5000' airport - even in the middle of summer - the mixture setting is not the problem. Something is seriously wrong with the engine or the baffling. That doesn't make the target EGT method "wrong", but I think you're over-emphasizing the importance of it on takeoff. It's not a critical number on the takeoff roll or the first 1000' of climb, and it's therefore arguable whether it's worth the distraction of looking at it during a critical phase of flight. It's not so much that it's a huge risk to take a glance, and maybe even tweak the mixture knob based on what you see. But doing so doesn't result in a meaningful difference in performance or safety, so why bother? Ignoring EGT details during this time gives you a few more seconds and neurons to look at things that matter more - like the actual CHTs, which could be the earliest indicators of a problem unrelated to mixture setting, and therefore should be monitored anyway (along with oil pressure and temp). You can glance at the EGT and make a mixture tweak later, at 1000' AGL and about every 1000' thereafter.

The Koch chart is fine, but the "nerd math" you're asking about is right there in the performance data from the POH I posted. You just have to interpolate. Compute takeoff weight with your particular load (including fuel) and interpolate between the 2300 and 2740 data points, then note the temperature at the selected pressure altitude and interpolate between the temperature points. Or vice-versa, you can start on either axis. At the risk of sounding like a jerk, this is basic private pilot stuff. Regarding mixture setting vs. performance, yes you need to lean appropriately for the DA, and target EGT is a fine way to do so. But note that the curve of power developed vs. mixture setting is pretty flat across its peak. Per the graph below, in the max power rage, differences of 200 degrees EGT only change the power developed by a few percent. So you're not going to see any meaningful difference in takeoff distance and climb rate by getting the mixture setting "perfect" vs. "good enough". This seems to be widely misunderstood, and I fly with lots of pilots who I think spend way too much time fiddling with the mixture during runup at higher DAs in normally aspirated airplanes. Set the mixture "pretty rich" just prior to runup; lean it promptly past peak RPM to roughness; then move it back to about peak plus roughly 1/2" of travel, and you're done. Takes about 5 seconds. If 2% power is the difference between clearing and hitting terrain, that's a judgement problem in deciding to take off in the first place, not a problem with leaning technique.

Having instructed in a few airplanes with a single, large glass panel that does "everything", I think there really is an advantage to having the engine instrumentation available on an independent device. The failure rate of the big panels is pretty low, but I'm obligated to simulate "partial panel" on an IPC, and if I choose to do that by simulating a backlight failure of the primary/only display (a very real possibility), it always creeps out the pilot that they no longer have any engine data. The antidote to that is to mange the engine solely by the physical position of the knobs that control it, which most pilots are pretty familiar with. That generally works fine, so I don't think it's some sort of critical error to bundle your engine data solely on a single TV screen with everything else. But it's worth thinking about.

I got curious about this as well and looked in the schematics. The gear selector switch is a DPDT switch, but the schematics for my 1976 M20F show only one pole being used. Moving the switch simply routes a single +12V signal from the landing gear breaker, to one of two output contacts, that - after traversing some of the safety and indicator mechanisms - actuate the "gear motor up" or "gear motor down" relay. It does seem like a single-point failure (broken internal switch guts, loose wire, etc) could command an opposite action from what the pilot selected. It's probably not a very likely failure, and often simple is better. But I'm still slightly surprised at the design.

Not sure what version of the M20F POH you're looking at, but the 1975 edition has takeoff and landing data up to 7500' at 70 degrees F, which is about 10,000' DA. Takeoff distance chart is pasted below, landing distance is shorter than takeoff distance for all cases. Real world performance of any stock, airworthy M20F is not meaningfully different from these numbers.

This makes sense, but I believe is considered poor practice. I'm sure driving multiple devices from one circuit breaker is done all the time including by major manufacturers. But I once called an avionics supplier about whether it would be OK to gang a voice annunicator that draws less than 100mA with an audio panel that specified a 3A breaker, and you would have thought I was Peter Graves being disavowed by the secretary of whatever. We were out of circuit breaker holes, and wound up powering the voice annunciator through a fuse - as allowed by its installation manual - that tapped off a 12V source right at the bus bars. We put it as close to the bus bar as possible, such that most of the wiring to the voice annunciator was downstream of the fuse.

It only has to do with where the fuse/CB breaker is placed, through the mechanical size of those different devices may dictate where they wind up. Otherwise, there is no truth to this idea that one type of circuit interruption device is designed to protect wiring and another to protect the appliance the wire connects to. That's just not correct. Both types of interruption devices can protect both wiring and appliances. Both types of interruption devices provide more safety when placed on/near the bus bar than on/near the appliance being powered. This is due to the nasty failure mode of a power wire which chafes and shorts to ground between the bus bar and the appliance, and winds up carrying more current than it's rated for. This type of failure tends to melt the insulation, dribbling hot, waxy gobs of plastic-like material onto surfaces like clothing and carpet that are prone to catch fire. It's nice to protect the appliance too, but the failure mode of an internal short in the appliance tends to simply burn out a component that's encased in a metal box. It could still hurt you or start a fire, but that's much less likely than an over-current wire. If you can only place one circuit interruption device in the electrical path to an appliance, putting it near the large, robust (cool) bus bar is good because it means most of the wire that might melt is "downstream" of the circuit interruption device. If you instead put the interruption device near the appliance, most of the wire that might short is "upstream" of the interruptor. That's true regardless of whether the poorly-placed interruption device is a breaker or a fuse.

Screen captures of relevant details for M20F s/n 22-1306 and on are pasted below, from a high-res schematic Mooney sent us a long time ago, and the service manual. Part numbers are OEM original from the 1970s. My guess is that some/all of them have been superseded, but you can look up equivalents online. Not sure what you mean by the "switch to drop the gear", as there are a number of switches in the system: the pilot control switch in the cockpit that selects gear up/down, the relays that power the landing gear actuator motor, and the limit switches that cut power to the motor when the gear reaches its final up/down position.

Peace and Godspeed, sir. Thanks for being part of our community.

The alternate air mechanism in the E/F is completely independent of the ram air port, and I suspect it's the same in the J. I've circled it in red in the figure below, clipped from the parts manual picture above. It's a round door at the back of the air box, which is ordinarily held closed by spring pressure. If the air pressure inside the air box gets sufficiently lower than the air pressure outside the air box (presumably because the normal intake path through the air filter is blocked), the air pressure difference overcomes the spring pressure and opens the door, drawing air from inside the engine cowl. The mechanism is completely automatic, there is no control in the cockpit for it. The mechanism should be periodically checked (annual, oil changes) for freedom of movement against the spring. Note that if you're in conditions which you suspect might clog the intake system (ice, volcanic ash, whatever), it is critically important to keep the ram air door closed. Opening the ram air door directly exposes the impact tubes of the fuel servo to an unfiltered air stream. If ice or dirt or whatever in that air stream clogs those tubes, the fuel servo stops working as designed, and it's pretty much game over. You can't fix it by closing the ram air door, and the alternate air door won't do you any good. I'd argue that the ram air port is actually the antithesis of "alternate air", since its use is more likely to cause an intake emergency than it is to bail you out of one.