Vance Harral

If you're serious, this seems pretty straightforward. Search NTSB records for Mooney gear-up landings, subtract out the ones where a per-wheel indicator wouldn't help you (e.g. collapsed after rollout, forgot to put the switch down, etc.). Everything left *might* be a failure of the type you describe. My guess is that number is very tiny, but I haven't researched it myself. Based on having inspected and handled the pushrods in question, it seems like it would take a tremendous amount of force to bend one in the manner seen in your photo above. How did that happen? It seems almost inconceivable to me that an electric gear actuator could do that (circuit breaker would pop first). If that's from a manual-gear airplane, it would seem someone with major muscles (or major motivation) must have really leaned into it. All that said, if this is really a concern for you, may I suggest installing a live streaming camera - e.g. a Garmin VIRB. The FAA has essentially capitulated on such things being "portable" devices that require no special approval to install. Clamp one on your tail tie-down such that it can see all three wheels. When you put the gear down, just take a look at the live streaming picture on your tablet or phone to confirm.

Yes, but only if there's been a major mechanical malfunction, such as the bent pushrod discussed above. The whole system consists of a series of interconnected pushrods. The switches and lights track the position of one of those pushrods, while the floor indicator tracks another. You can see exactly which pushrods are monitored by looking in your parts manual and/or at your airplane next time you have the belly panels off. But nothing tracks the "final" pushrods attached to the gear trusses and/or the over-center links, hence Mooneymite's concern

I guess my question is to what extent Mooneys have suffered more, or more injurious/fatal accidents as a result of this "flaw" in the indicator system, vs. GA retractables with per-wheel indicators? We have 50+ years of data on this, what does it say? You're certainly correct that there are failure modes which are not caught by the current indicator system. But it's not clear a different system would save more lives or dollars. Don't forget that a more complex indicating system would have more complex indicator failures, potentially leading to bad outcomes that would not have happened with the simpler system. In my 25+ year career in engineering, I can't tell you how many times I've seen systems that were (re)designed to catch some corner-case failure, actually wind up causing more trouble than the original corner case. My gut instinct is that when each wheel is an independent system (e.g. hydraulic), independent indicators are a good solution. With the mechanical linkages in our Mooneys, the combination of an electric (switches) and mechanical (floor line) indicator seem quite adequate.

Agreed, those are the jump planes and they do enter the pattern from steep descents. On the other hand, I've never personally had a "crazy skydive pilot" scare in 15 years of flying at Longmont. I find the current batch of jump pilots to be professional. They pay attention to what's going on in the pattern as soon as they roll in after the drop, position appropriately on the way down, make reasonable radio calls, and work into a reasonable spot, slowing down if necessary to do so. No dive bombing in front of everyone, as seems to be the stereotypical complaint about skydive ops. This is not to say I've never heard a single complaint about the jump planes. But to be honest, the complaints I recall tended to come from pilots who I felt lacked some experience and understanding of different speeds and energy management. A King Air entering mid-field downwind at 150 knots is not "cutting in front of you" if you just turned crosswind to downwind at 75 knots in a 172.

As a local, I'm inclined to say this sounds like a bigger deal than it really is in practice. The jump aircraft inform Denver TRACON when they're about to drop, and also make an announcement on the KLMO CTAF. So if you're actually going to Longmont, you'll hear about jump activity one way or the other. The only thing you need to do differently is not enter the pattern by flying directly over midfield into the downwind leg (use a 45-to-downwind or enter on base or crosswind). Once you're in the pattern, you just fly a normal pattern, even with jump activity. The jumpers come down south of the runway, with plenty of clearance from the runway itself, as well as the downwind leg. In my opinion, the biggest risk from jump activity around Longmont is to transient aircraft trying to squeeze between the mountains and the western edge of the Bravo without talking to anyone. Pilots unfamiliar with the area might use KLMO as a landmark and fly right over the top without being aware of jump activity.

Well, it goes up to 12K. Agree an Ovation can easily top that, but I wouldn't necessarily recommend flying over the top of the bravo as a routing strategy. It would be a heck of a slam dunk from the west edge to any of the local airports. 12,500' also puts you right around the altitude of the highest peaks to the west, and hence in the worst turbulence from the very common westerly winds. Instead, I'd advise taking advantage of IFR services or VFR flight following from Denver TRACON and just going through the bravo. I know a TBM driver who gripes about the routing they give him coming into Denver because he's up playing with the jets. But they've always treated me well down at piston altitudes. Not sure what altitude the OP likes to cruise at, but the most reasonable rides on summer afternoons here are going to be either below 9000', or way high, like 18K and above. The latter isn't really practical in an unpressurized aircraft. The direct route from Chattanooga does go right over KDEN, and ATC is unlikely to clear you on that route (though they'll occasionally let you go right over the top of the runways). But a minor deviation to the north (say, via the AKO VOR) is likely to get you cleared through the north side of the bravo at a reasonable altitude, whether VFR or IFR. Lots of options out that way too, if you need to wait out a line of afternoon T-storms and complete the trip after dark. KAKO is an obvious choice, but don't count out KFMM in Fort Morgan. It's a small airport and a small town, but they have a courtesy car you can take into town for dinner, and you can get the keys after hours even when the airport is unattended.

Robert, when you finalize your trip details, feel free to PM me. Our airplane is based at KLMO, and I live just a couple of miles from KEIK. Always happy to help out a fellow Mooney pilot with a ride or whatever. With sufficient notice, I can probably loan you a car for a couple of days if you like. My advice is to not necessarily get fixated on a particular airport. KBDU in Boulder itself is a decent airport in good weather. But KBJC, KEIK, and KLMO are all very reasonable driving distance to Boulder (about 20 minutes), so you have a wide variety of choices for approaches, runways, etc. All these airports have maintenance facilities and self-service fuel at reasonable prices. All have transient parking. There may be overnight charges at KBJC, I'm not sure about that, but you can always call and ask. I can vouch for the folks at Fly Elite Aviation in Longmont. They'll take care of your airplane, minimal/no fees to park on the ramp, and they have competent mechanics who are Mooney savvy on the off chance you have a maintenance issue (we have all our maintenance and annuals done there). If you're more comfortable with towered airports, KBJC is towered and has upscale FBOs with nice lounges, TVs, etc. As for KBDU, while it is indeed closer to the mountains and lacks approaches, the truth is it's rare to "need" an instrument approach around here. The weather tends to either be good VFR, or unflyable IMC due to icing or thunderstorms. Concur with the advice of others that things are statistically easier if you arrive in the morning, having holed up in Kansas or eastern Colorado the night before. But it's also completely reasonable to delay your decision of a specific airport until you're an hour out or so, then just take whichever of KBDU/KBJC/KEIK/KLMO seems best suited for the weather conditions. If you need or want to make a local flight for pleasure or to re-position your airplane, I'm available as an "advisory" CFI. No charge for fellow Mooney drivers.

Mooney by moonlight, just this week.

A respectfully dissenting opinion: We bought our 1976 F model with an inop Brittain B-5 system, and eventually restored it to fully operational condition. The downsides are that it took a lot of time and energy to do so, and the end result doesn't perform nearly as well as a modern digital autopilot. The upside is that our total investment - and I mean total investment over the last 10+ years for everything from overhauled servo boots, to flaky rotary switches, to IRAN'd valves, remote compass unit, etc - is well under $2K. This for a 3-axis autopilot that holds altitude, tracks headings, courses, performs approach intercepts (lateral only, no vertical), and works well with the GI-106 indicator driven by our GTN-650. Brittain can even set you up with GPSS if you like, though we haven't gone that route. It's not a great autopilot compared with modern options, and I wouldn't recommend taking on the job of fixing one unless you're a techie type who really enjoys reading the old manuals and doing a lot of owner-assisted maintenance with the help of a friendly A&P. But the support from Brittain has been great, and the value for the dollar is absolutely unbeatable.

Thanks, guys. I'm aware of the accident history, but hopeful it was repaired instead of scrapped. I may try e-mailing Ridgeaire.

This is a long shot, but I'm inspired by @Rmag's thread here. In the mid-80s, my father owned a share of N55FE, a 1965 M20E. Long before I took any formal flight training, he introduced me to basic control and navigation, and I have fond - if vague - memories of the airplane. It's registered to a Delaware corporation these days, and hasn't shown up on FlightAware since 2010. Thought I'd make a quick post here and just see if the current owner is on Mooneyspace. I'd love to see what N55FE looks like today.

These pictures here are great. The original A model evokes everything classic about Mooney lines and curves, and the individual specimens look well cared for. Congratulations to you all! mike20papa, I trained at KCLL and have a number of Coulter field landings in my logbook too. All from "back in the day" when I was a student at A&M. Love the paint and aluminum combo on your airplane. Wave at all the Aggies for me next time you're airborne.

Thanks air cooled dad. I see you have the exact model of actuator I do, with the infamous Adel clamp as well. That gives me at least some confidence our setup isn't just a shade-tree mechanic's kludge fix. Yetti, I shouldn't have said you have a "newer" actuator, just a "different" one. I assumed the LAC2116 in your airplane was newer than the LAC2114 in mine because the number was bigger. But that appears to not be the case. We have never adjusted the backlash on our actuator. I'm not entirely sure what you mean by that. I understand "backlash" to mean the space between the worm and pinion gears. Maybe you're referring to adjusting the emergency engagement lever? If so, no, we've never adjusted that either. All I know is the entire actuator was rebuilt by LASAR a few years back (they did more than just install the 40:1 gears). I'm inclined to assume it was adjusted at the time.

Can you elaborate on this particular point? Our unit actually failed the SB-190B inspection a few years ago when it had the 20:1 gears - both the worm gear and the pinion gear were scalloped to the point they had more than a half tooth of lash. This happened after about 8 years of dutifully pulling and re-greasing every 200-ish hours, so it wasn't due to old grease, just accumulated wear over 30 years. I definitely saw the gears wearing down over time, and I knew the unit was going to fail the inspection sooner or later. After 7 years on the 40:1 years I'm already starting to see very slight wear on them, though the system is still very tight, and probably decades away from failing an inspection. The wear rate anecdotally appears much slower to me vs. the 20:1 gears, so I'm happy to have the higher ratio. I'm aware it takes twice as long to raise and lower the gear, but the performance impact is negligible in practice. Curious why you think going to 40:1 gears is a negative.

I appreciate the ideas, Yetti. I may be able to get my mechanic to sign off on a minor mod that's more robust next time we have all this stuff apart. In the mean time, I know we have a few other 1976 M20F owners here on Mooneyspace. I'd love to see exactly what's installed in their airplanes. Having seen your picture where the L brackets just attach to the motor end plates - which my actuator has as well - I'm starting to wonder if that Adel clamp was really the factory solution after all. It's possible some prior owner lost the brackets and/or the magic unobtanium nuts, and the clamp is a kludge fix.

The picture in your post is an ITT LA11C2116 - different model than in my airplane (I think it's an even later follow-on to the LA11C2114). It obviously has the mounting holes for the bracket. Bracket(s), actually, I see yours has two. I agree it's a superior arrangement, I wish we had it. The only upside of having the LA11C2114 is that because it's technically not called out in the AD and SB, we don't have to strictly adhere to the 200 hour inspection limit. I don't worry about it if we go something like 210 hours between inspections, especially since our unit has been rebuilt with 40:1 gears.

My (limited) understanding is the second attach point has changed over the years, depending on M20 model and the exact landing gear actuator installed. The diagram in my parts manual actually shows a bracket attached to the back of the actuator to support the cable rather than an Adel clamp, but I believe that is specific to the Dukes 4196 actuator installed in earlier F models. By the time our airplane was built (1976 model), the Dukes was no longer available, and Mooney had moved to the ITT LA11C2114 actuator. That one lacks the bracket mounting holes shown in the parts manual diagram. I'm guessing the Adel clamp is a workaround. If yours doesn't have the clamp, I'd guess it has the bracket attached to the actuator. It's possible the attach point is on the fuselage as you describe. But in our airplane, the nearest fuselage stringer is too far away from the lever to make a good support point for the cable. Interestingly enough, the ITT LA11C2114 actuator in our airplane isn't actually called out in SB-190B or either of the landing gear actuator ADs. But we treat it as if it was, per advice from Don Maxwell.

All emergency gear systems have failure modes, and I'm not inclined to think the one in "vintage" electric gear Mooneys (I have an F model too) is any worse than others. In the honesty department, however, I'll say it has adjustment requirements that are something of a pain, and can be error-prone. You'll run into this because properly maintaining an electric gear F model requires pulling the gear actuator every year or two for inspection, to comply with SB M20-190B. On the plus side, this is an opportunity to inspect the whole system and understand how it works, check for wear, etc. On the minus side, it provides a regular opportunity to screw up the delicate adjustment of the emergency engagement cable. To wit, removing the actuator for inspection requires disconnecting the emergency extension engagement cable from the actuator. The cable attaches to the actuator at two locations. The first is the end of the cable which actually moves the engagement lever (first picture below). Moving the engagement control in the cockpit forward pulls this cable to engage the manual crank. Moving the cockpit control aft releases tension on the cable, and the spring you see in the photo is supposed to pull the lever to the disengage position. If the spring gets reinstalled with the ends swapped, the positioning and tension changes. Same if the complex collection of nuts and washers holding the cable gets re-ordered (and yes, it really is supposed to look like that, Rube-Goldberg-ish as it is). But arguably those things aren't a big deal. Just be careful, refer to the parts manual, and put everything back together the same way it came out, right? Well, sorta. In the second picture below, you'll see another attach point for the cable. It's effectively stiffened by a support bracket that's just a big Adel clamp around the housing of the gear motor. There is no detent in the housing to force the Adel clamp into a particular position, it just gets shoved on to the housing and tightened up. In fact, you can see mine is a bit crooked in the photo, that was done on purpose. When this clamp is re-installed, any minor change in position changes the relative location of the cable endpoint that attaches to the engage lever. Get it too far forward and the emergency extension gear only partially engages when activated (it grinds and/or binds up). Too far aft and the spring doesn't have enough tension to disengage the system, with the novel failure mode of the emergency gear handle whipping around wildly and beating your arms/legs when you retract the gear electrically. To make matters worse, the system has observer effect, wherein operation for testing can move the Adel clamp around if it's not very snug, resulting in mechanical hysteresis. Because of this, I'd never trust a single test of the system after a gear actuator R&R, I always do several. I'm sure Mooney-savvy shops do the same, but not every shop is Mooney-savvy. I've R&R'd our landing gear actuator numerous times over the last 13 years, and I consider myself pretty familiar with it. I'm always careful with removal and re-installation, even under the "adult supervision" of an A&P. And yet, about every other time I do so, a bit of tweaking is necessary to get the system adjusted properly so it reliably engages and disengages over multiple tests. I've seen it misbehave when not perfectly adjusted (that's how I know what the failure modes are). I've seen it work on a first test and not on a second one. And if you need convincing this can fail "in real life", I refer you to the gear-up landing by a prior owner in our logbooks, which was blamed on this exact mechanism being mal-adjusted. The pilot ran out of electrons, and when he attempted to lower the gear manually, the engagement lever didn't fully engage, and the crank jammed. So... while I don't know your buddy's actual experience with Mooneys or exactly what his concern is, I think it's fair to talk about vulnerabilities in the system. I think the basic idea of using a manual gear on the other end of the motor shaft to turn the system is sound, but the way that gear is engaged/disengaged doesn't seem especially well designed to me. To be fair, the factory probably didn't envision everyone pulling the landing gear actuator out of the airplane every year or two when the system was designed, but that's the situation we have now.

Seconded. We're very happy with our EI AV-17, but there are other choices too.

That's interesting. The maintenance manual for my 1976 F model lacks detail on this, but your comment moved me to go look in the more detailed maintenance manual for the 1977 J model - which I believe uses exactly the same senders and gauges as my airplane. That manual does have a calibration procedure for the gauges. It says the gauge must match actual fuel level within 1/2 needle width at empty (zero usable fuel), 1/4, 1/2, 3/4, and full. I'm not sitting in front of the airplane, but my recollection is there's roughly 1.5 inches of span between the E and F marks on the gauge, and the needle is about 1/16" (0.0625") wide. A 1/2 needle width error would therefore be about 0.03125/1.5 = 0.021, or about 2%. The catch is, the fill procedure allows for -1/+2 gallons of error in the 8 gallon increments used to fill the tank to the 1/2/3/4-quarter levels. So at the quarter tank mark, for example, you could have as much as 10 gallons instead of 8, which is 10/32=0.3125 of a full tank. The needle could be 1/2 needle width below the 1/4 mark and still meet spec. In that case, the needle would indicate ((1.5/4)-.03125)/1.5 = 0.2292 of a full tank. That's an error of 0.3125-0.2292=0.0833 of a tank, or about 8%. I won't argue with the characterization of 8% as "lax" compared with the 3% spec in TSO-C55a. But we're still talking about error in the range of a needle width or so. That's a lot more accurate than I think most pilots would guess is required of the fuel gauges.

My knowledge of fuel indicator regulations doesn't come from vast professional experience, just an hour or so of actually reading the regulations and associated ACs, motivated by a "that can't be right" skepticism of the myth. I'm not inclined to apologize for holding other pilots to that same standard, but it's not my intent to be a jerk and/or a know-it all. I do apologize for any brusqueness, and freely admit plenty of personal ignorance on other subjects. Your specific question is an opportunity to admit ignorance myself. TSO-C55a specifies accuracy tolerances of 0.75%, 2%, and 3% for class 1/2/3 indicators, respectively. I don't know what constitutes a class 1 vs. 2 vs. 3 sensor, that appears to be defined in an SAE publication I haven't read. Maybe fuellevel can explain. Even three percent is a pretty tight constraint. That's less than one gallon in the 26-gallon tanks in each of the wings on my airplane. I'd be unlikely to notice or care if my gauges read half tanks when there were really 14 gallons in the tank instead of 13, even though that's technically beyond airworthy tolerances. But if the gauges showed 3/4 tanks when the dipstick showed 10 gallons, I'd consider it a malfunction to be fixed immediately.

With respect - and I mean that honestly - I don't think you understand the meaning of the word "accuracy" in the context of measuring devices. The part of the regulation you quoted says "zero". It doesn't say "zero plus or minus one gallon", or "zero plus or minus one percent of the total fuel quantity", or anything else of the sort. Those would be accuracy constraints. The point of subpart (b)(1) is clearly to define what zero means, not to specify the accuracy of the measuring device which indicates it. You're grasping for a definition which fits the funny joke about the fuel gauges only having to be accurate at zero, but that's neither the letter nor the intent of the regulation. But don't take my word for it. The FAA's guidance to people who certify airplanes to part 23 regulations is laid out in AC 23-17C. Here's a particularly telling paragraph from that publication, from page 269: Fuel quantity indicators are also governed by § 23.1301, as are all 14 CFR, part 23 Subpart F appliances. This regulation requires the installed indicators function as designed and not create a hazard in their operation. This precludes indicators that read higher than the actual fuel level since this would constitute a hazard. The AC also makes reference to any changes in fuel quantity indicators needing to meet the standards of TSO-C55a, as fuellevel mentioned above. That TSO details the required accuracy for various classes of fuel and oil quantity indicators. It doesn't contain the word "zero" at all. The accuracy requirements it specifies apply across the full scale of the indicator. I grant that those publications didn't exist in 1965. But you have to really grasp at straws to claim the FAA's position even in the CAR 3 days allowed fuel gauges to be wildly in error at any level above zero usable fuel. That was never the intent or implementation, and aircraft with grossly inaccurate fuel gauges have never been legally airworthy.

Yes, that's my understanding. I suppose it's possible Mooney and the FAA pencil-whipped the certification process, I can't prove they didn't. But it's unlikely. CAR 3, specifically CAR 3.672 which isn't much different from FAR 23.1337. My point isn't a question of "trust", it's just about what the certification standards require. That said, ignoring fuel gauges because you think they're so inaccurate as to be worthless removes a valuable tool from your fuel management strategy. It's akin to saying you don't trust your attitude indicator, but it's acceptable because you have needle, ball, and airspeed. Or that you don't trust your nav radio but it's acceptable because you have an iPad. There are certainly pilots that do such things and I'm not going to be holier-than-thou about it. But such aircraft aren't in compliance with their basis for certification, and are less safe than aircraft with all redundant systems functioning as designed. If your fuel gauges are that far off, the gauges and/or the senders need servicing. They certainly were not designed to such lax standards. You seem to have the impression it's not possible to maintain the fuel gauges to reasonably accurate standards because they were never designed to be accurate in the first place. That's just not the case. Sure, the wiper-arm potentiometers on the sender wear out and need to be serviced or replaced, the springs on the gauges themselves may wear over time, etc. But those are long-term maintenance requirements, not design limitations. Servicing your fuel indicating system is no different than replacing shock disks, resealing fuel tanks, replacing trim jack screws, or any other PITA issue we'd all like to avoid, but which are in fact the standard of care for airworthiness.

No other regulation is needed for clarification. FAR 23.1337 doesn't specify an accuracy constraint, but neither does any other powerplant gauge regulation in Subpart F. In fact, 23.1337(b)(1) doesn't specify an accuracy constraint for "zero", for that matter. What 23.1337 does say is, "An indicator calibrated in appropriate units and clearly marked to indicate those units must be used." No reasonable interpretation of "calibrated" would allow for wild inaccuracies in fuel gauges across their full range. If you actually read all of 23.1337 in context, it's clear sub-part (b)(1) is written to address the difference between zero absolute fuel vs. zero usable fuel. My guess is someone made a clever joke about 23.1337(b)(1) a long time ago, and it somehow "went viral" long before the modern interpretation of that phrase. For anyone tempted to devolve into pedantic parsing of the absolute letter of 23.1337, just look at the big picture. FAR 23 is filled with regulatory requirements about instruments. Most use essentially the same type of "calibration" language, and lack any numerically-defined accuracy or precision constraints. But we don't make silly arguments that oil pressure or CHT or tachometer gauges have absurdly lax accuracy standards. Grossly inaccurate CHT/tach/etc. gauges certainly wouldn't pass muster with a DER or other certification authority, despite the lack of specific accuracy/precision constraints. Neither would fuel gauges.

Completely incorrect, please stop propagating this old wives' tale. The certification standards require fuel gauges to be accurate throughout the complete range of the indicator. The myth comes from a misunderstanding of the sub-part dealing with usable vs. unusable fuel. I don't mean to be a jerk about it, but propagation of this OWT is a substantial reason fuel gauges get signed off when they're actually unairworthy. This just further propagates the myth they're less reliable or less important than other critical indicators. I'm sure this drives the professionals absolutely nuts. The OEM fuel gauges in your Mooney and other GA aircraft are designed to be reasonably accurate throughout their range. They need to be, because gauges are the only mechanism that will detect a developing, in-flight fuel system leak. Totalizers and timers are of course excellent safety guards against fuel starvation, but they're meant to supplement the gauges, not replace them. If your gauges are inaccurate, your aircraft isn't in compliance with its type certificate, and it needs maintenance. Kudos to the OP for wanting his fuel gauges to be accurate, and to businesses like CIES for providing technology that improves accuracy and reliability.