Vance Harral

Fair question, and one of the things we checked when deciding to install. With the balls on the yoke and the compass up on the center post, the distance is large enough not to have any effect. No, I didn't do a full before/after compass swing. But before attaching, I moved the ball mounts from "far" away, up to the yokes, wiggled them around in the yoke area, and didn't see any visible movement of the wet compass. This is not an acid test, but no worse in practice than avionics shops which never re-swing the wet compass after installing new gizmos, even though it's technically required. Data point: I have a magnet of similar strength on my key ring, and I put the keys on the glare shield during preflight, which tends to wiggle the compass. I worry a (very) little bit about buggering the compass that way, but I confess I just do it anyway. That key ring magnet needs to be within about 12" of the wet compass to actually produce any visible movement. If I put it on the far edge of the glare shield, the field strength just isn't big enough to matter to the compass. Makes you appreciate how strong the "weak" magnetic field of the earth really is.

Not until just now!

That's a Nite-Ize "Steelie Ball" mount for phones/tablets. https://www.amazon.com/Nite-Ize-Original-Steelie-Magnetic/dp/B01JJP5JAW/. Note that this link is to the larger, more expensive size, designed for tablets. Don't confuse it with the smaller, less expensive size, designed for phones only. We have one of these mounts on each yoke in our airplane. It's far and away the best phone/tablet yoke mount I've found, for a couple of reasons. First, there's nothing faster than a magnetic mount for attach/de-attach. Just pop the device on/off the yoke in a half second. No clamps, no tabs to click in, etc; just on and off, immediately. Second, a ball mount allows you to swivel your phone/tablet around on the yoke. Very handy if you want to switch from portrait to landscape orientation, or just make a slight adjustment when the sun happens to hit an angle that causes glare and/or a blinding reflection.

That sounds about right to me. Labor adds to the $700 kit cost if you're not your own A & P, but swapping injectors is not a labor-intensive job. Maybe a couple hours worst case (sometimes you need to go multiple rounds of swapping with GAMI to get the absolute best result). Call it $1000 all-in, and a 200 hour payback worst case. This is a theoretical argument that assumes one meticulously manages the mixture at all times. If you're a little lazier like most of us, and/or spend a lot of time flying around the pattern, doing IFR training, etc., you're not going to save the full 0.8gph during every hour of operation. Regardless of those quibbles, though, there is always going to be a break even point within a few years. Up to each pilot to decide if that's the best use of their dollars compared with additional training or other alternatives. Let's try not to confuse the original poster, who has a normally aspirated engine (as do I). Turbocharged Senecas and 252s have the option to run LOP in cruise while still maintaining "rated" cruise power (60%, 65%, 70%, 75%, whatever - take your pick based on desired engine longevity). One can simply push the throttle forward, increase manifold pressure, and maintain rated power up to the critical altitude of the turbo. That ability to maintain rated cruise power and run LOP without slowing down is attractive. If I had the privilege of operating a turbo'd bird, I'd likely fly LOP in cruise. At optimum cruise altitudes in a normally aspirated engine, however, it's a tougher sell. Running LOP and also making rated cruise power requires staying low, where additional drag is working against you. Climb up to optimum NA density altitudes of around 8K and you're likely below max rated cruise power even at the best power mixture. Going LOP there slows you down. Still a great tool in the tool bag for increasing range when needed. But a lot of us normally-aspirated drivers just can't stand to give up the knots it costs to get the benefit, even though that's an emotional argument that has little impact on real-world, door-to-door enroute times.

If we're going to get into details, let's get it exactly correct. Balanced fuel flows across all cylinders increase engine smoothness at stoichiometric mixtures, and mixtures lean of stoichiometric. Producing the same amount of power under these conditions requires injecting the same amount of fuel, because fuel is the governing input to the combustion equation. Unequal amounts of fuel -> unequal amounts of power developed -> engine roughness. But unbalanced fuel flows across all cylinders in rich-of-peak operations have (almost) no effect on power developed, and therefore no effect on engine smoothness. The reason is that the excess fuel in a rich mixture is simply unused, and blows out the exhaust unburned. It doesn't matter whether you have "a little" more fuel than the stoichiometric ratio, or "a lot" more. The power developed is the same (well, aside from the effects of small differences in additional cooling, and the density of the material exiting the exhaust system, which explains the less-than-flat power/mixture graph on the rich side). If your point is that unbalanced fuel flows across cylinders can allow some cylinders to be ROP while others are LOP, sure, that's true. But that is not "best power", which is the point you are emphasizing: Best power in an aircraft cylinder is always rich of peak (100-200 degrees ROP for the typical Lycoming, see graph below). If the mixture crosses over into lean-of-peak operation, the cylinder is not running at best power. Furthermore, as the graph shows power decreases more quickly on the LOP side than on the ROP side. So in an engine with less than perfectly matched fuel flows, best power is achieved when one cylinder is around 150 degrees ROP, and all other cylinders are still ROP. Again, if any cylinder actually crosses into LOP operation - where fuel flow does affect the power developed - that is by definition not best power. LOP operations tend to produce plug that look nice when pulled for inspection and gapping. But let's be careful with the word "fouling", and distinguish cosmetics from actual mis-firing of the plug. As a primarily ROP-in-cruise flyer, I have zero problems with misbehaving spark plugs. This is almost certainly because I aggressively lean during low power ground operations, which is where essentially all plug-fouling-of-the-type-that-causes-misfire occurs. Barring very extreme cold weather operations, any power setting actually used in flight produces sufficient cylinder combustion chamber temperatures for the lead scavaging agents in the fuel to do their trick, and it's generally lead contamination that causes poor spark. Again, the plugs from a primarily-LOP-flown engine will tend to have just a hint of light brown residue on the plugs, while a primarily-ROP-flown engine will have a heavier, blacker residue. So LOP is "cleaner" for the plugs, no argument there. But not cleaner in a sense that actually matters. I'm not finding huge balls of lead down in the plug well when I pull my plugs for inspection and gapping, and I don't have problems with mis-firing plugs. Concur, no argument. If I had GAMI injectors, then instead of flying with one cylinder at 150-ish ROP and some of the other cylinders even richer, all the cylinders would operate right at 150-ish ROP at the best power setting. There would be no difference in the power developed or the speed I traveled at vs. without GAMIs, but fuel flow would be a few tenths of a GPH less.

Some additional info: the basic reason for wanting closely matched fuel flow from each injector is to allow the engine to run smoothly when all cylinders are operating lean-of-peak (LOP). If you want to operate in this regime, (more efficient, cleaner, but always slower in a normally-aspirated airplane), then you *might* want GAMI injectors. If you don't care about operating LOP (value speed over efficiency, don't have problems with plug fouling, etc), there is little reason to invest in them. As a data point, the famous "GAMI spread" in my IO-360-A1A is not particularly good - about 1.0 GPH difference in fuel flow between the points across which the four cylinders hit peak EGT. But I'm still able to operate with the last cylinder to peak running at 10-20 degrees LOP. The engine runs a little rough at that setting. Not "OMG it sounds like it's going to quit" rough, just a little fatiguing. I don't particularly care about that, because I rarely choose to run LOP. Therefore, I'm not especially interested in GAMI injectors. If I had problems with plug fouling, was more concerned about CO poisoning, or just really enjoyed the efficiency vs. speed tradeoff, I'd run LOP and likely invest in GAMI injectors.

Cleaning the engine to bone dry is indeed the first step. Once that's done, I've had good luck with UV leak detection dye, e.g. https://www.amazon.com/Interdynamics-Certified-Fuel-Systems-Ounce/dp/B002M4G24U, a trick explained to me by a long-certified A&P mechanic. Get everything bone dry, pour a bottle of the dye into the oil fill tube (don't spill it outside the engine!), run the engine at high power for a short period of time on the ground, de-cowl, and use a cheap UV flashlight in a dark hangar to look for the source of leaks. I know of no specific regulatory prohibition on doing this, but I make no claim that it's legal/approved/etc. The most conservative approach is to do this coincident with an oil change. Add the dye right before the change, ground run the engine (to warm it up for the oil change, natch), identify your leaks, then drain the oil-with-dye as part of a normal oil change before you fly again. There is no particular reason to fly with dye in the oil anyway, as airflow through the cowl at speed just tends to blow leaking oil away from the original source of the leak anyway. For what it's worth, we did this after the conventional steps of replacing the rocker cover gaskets, tightening up the couplings on the cylinder head drain-back tubes, etc. What we found was a small leak at one of the pushrod tube seals that we had fixed, and a series of small leaks around the oil pan gasket, which we have chosen to live with in the short term (dropping the oil pan to install a new gasket is somewhat major surgery).

Thanks guys. Sounds like the over-center mechanism isn't actually going over center when the knob is all the way forward. I'm hoping the fix is as simple as adjusting the cable in such a way as to find a sweet spot between the over-center mechanism engaging as designed, but not getting false ram air warnings.

Thanks for the replies so far. These are Slick 4347/4370 mags, sounds like no lock washer. These are overhaul/exchange mags, installed 4/26/2019 when the prior slick mags failed inspection. They have about 250 hours of service to date. They were timed at the annual about 8 months and 80 hours ago, by the shop A&P; but I don't know if they were actually "touched" at all then (I wasn't there, sometimes the timing checks fine and no adjustments are necessary). So no very recent maintenance, and I don't have any particular reason to believe the screws were installed incorrectly last time they were touched. Perhaps this is just one of those things to check every time the cowl is off.

My airplane partner graciously performed an oil change today, and called to say that when he removed the oil filter, he found a machine screw sitting on the "shelf" directly under the filter. On further investigation, he traced it to the ignition wire cover plate for the left mag, as shown in the attached photos. Neither of us are A&Ps, and we're not sure of the implications of this. My partner re-installed the screw, used his general mechanical experience to torque it to what he felt was "about right", and performed a post-oil-change run-up and mag check with no issues. But we're between A&Ps at the moment (our on-field shop recently closed), so I'm asking the collective wisdom of Mooneyspace for further guidance. The screw in question doesn't have any kind of lock nut that we can tell. Seems like it's secured only by friction, which is a little creepy. Other than checking all the other screws on both mags, anything else we should do before flying again? Any guess what might have caused it to back out? This is the first time we've had a problem like this in 17 years of ownership, so I have no prior experience.

The official definition of "bad" is found in the service manual. To quote from that manual, "Slow-to-heavy seeps occurring in open areas, such as wing surfaces exposed to the airstream, are leaks which do not constitute a flight hazard and and need not be repaired prior to flight, providing the condition causing the leak cannot result in a leak of greater intensity during flight." So if your "very bad" leak is on the wing surface or in the gear well, and isn't causing a stain of greater than 4 inches in diameter, you have some time to consider your options while continuing to fly the airplane. That's the case with most leaks. If you actually have a running leak as shown below, or fuel is pooling and/or leaking down into the belly of the fuselage, a more urgent repair is necessary. We've had both conditions on our airplane. Over the course of 17 years of ownership, we've had the fuel tanks patched three times, at a cost of $1-2K each time. Only one of those was an urgent situation. Fortunately in that case, the leak was on the outboard side of the tank. We were able to drain that tank down below the level of the leak, keep the other tank full, and fly to the nearest MSC for a patch.

Parker is the expert, but in my experience as a CFI, there is no universal answer for this - it depends on the particular insurance company and the particular time you ask them. Working with clients for checkouts, I've had one company tell me the M20J and everything prior to it are equivalent, and another insist each of M20/M20A/M20B/M20C/M20D/M20E/M20F/M20G/M20J are all different. Similarly, some insurers group all turbocharged Mooneys together, others treat M20K/M20M/M20R/M20S/M20TN as unique animals. Any given insurer may change their mind on this from year to year. Bottom line, you have to call and ask.

You already figured out the simplest answer. Push the button when making a turn, release it when the turn is done.

It'd be a shame to not make use of a functioning wing leveler just because the disconnect mechanism isn't working. When you say the wing leveler "would not turn off", I assume you're talking about the red, yoke-mounted PC defeat switch? If so, in the mid-70s vintage Mooneys that is an electrical switch which connects to a vacuum solenoid behind the instrument panel, that opens the PC system to ambient air. It's pretty straightforward to test, might be as simple as a broken wire that just needs to be reconnected. If the yoke-mounted switch itself is bad, it's not too awful to replace, and it's a standard electrical switch that can be obtained from Mouser, Digikey, etc. If the vacuum solenoid is bad, replacements are hard to come by, but they can be gray-market overhauled. Its just a solenoid attached to a Schrader valve.

While Stratoflex may be the gold standard, I'm unaware of any guidance or regulation which prohibits the use of clear polyethylene tubing in the vacuum system. Almost all the tubing in our vacuum system is clear polyethylene, some of it installed by multiple shops I trust. That said, polyethylene tubing doesn't turn yellow overnight, and the hoses in your pic look significantly yellowed. When poly tubing gets old, it both turns yellow, and also gets brittle, possibly introducing debris into the system. So even though you've solved your original problem, I'd recommend replacing that tubing next time you're in there. If it were me, I'd just replace it with fresh poly tubing, rather than the more expensive Stratoflex.

CA comes in various viscosity formulations. Suggest you acquire some "thick" CA for this task, e.g. https://www.amazon.com/ZAP-Slo-Thick-CA-Glue/dp/B00V6DOYBG. Much less likely to run down out of the cap into the switch.

Yep, that's the one. It looks slightly different in models with electric flaps, which is why I didn't post a picture from my airplane. But the linkage is similar in both electric and hydraulic flap airplanes, with roughly the same (low) probability of an asymmetric failure.

That torque tube doesn't connect directly to the flaps. Arms are welded to the torque tube on each side, and those arms drive a pair of connected rod ends, which in turn drive the flap. See screenshot of parts diagram from the IPC below. Among other reasons for this design, it allows the flaps to be adjusted independently by turning the rod ends. Mooneys are certainly less susceptible to asymmetric flap deployment than some other models, and I'm not aware of any Mooney accident reports associated with asymmetric flaps. But I count four welds/linkage points between the torque tube and the flap on each side, the failure of any one of which would result in that side's flap hanging loose in the breeze.

I think I've done a poor job of communicating here, let me try again. For vintage Mooneys, it's my understanding that the Weight and Balance Record legally has to be carried in the airplane, along with the Operators Manual. The idea is that you're supposed to be able to run a W&B check using only the documents in the airplane. Accordingly, in the unlikely-but-theoretical case of a ramp check, you could catch a violation for not having the Weight and Balance Record document in your vintage Mooney. Yes, the odds of such a violation actually happening are astronomical - we're just talking theory here. Whether you use that document in your own W&B computations is entirely up to you, particularly in the modern world of EFBs. There are certainly other places to get the data and/or build an EFB W&B model. I don't think there is any reasonable interpretation of the regulations which would require a vintage Mooney pilot to perform W&B computations using only the smudged, micro-size-font graphs in the 50-year-old Weight and Balance Record. My CFI follow-up comment on this is, just make sure you understand the provenance of your W&B tool(s). In a training or flight review situation, I'd be really comfortable with a pilot who showed me a W&B using arms from the M20F (or G or J or whatever) TCDS entry. Also really comfortable with a W&B in Foreflight where the pilot says, "I created this W&B model in Foreflight using information in the TCDS/Weight and Balance Record"; or "I downloaded this model and checked it against the documents for my airplane". I'm a lot less comfortable when a pilot says, "I do my W&B in Foreflight", with no further explanation. Maybe this is less of an issue with Mooneys, but my worldview is biased by flocks of renter airmen who Google "Cessna 172" on the internet to get operating documents, and aren't yet skilled enough to understand the differences between a 1956 straight tail, fastback 172 (no trailing alphabetic character on that model), a post-2000 Cessna 172S, and everything in-between (including the ubiquitous 180hp aftermarket STCs). For example, not to pick on JWJR, but the specific language he uses to ask if Foreflight is "legal" makes my Spidey Sense tingle. Setting aside the question of FAA violations, what I really want to know is, where did he get the Foreflight model he's using, and how certain is he that it applies to the specific model of Mooney he flies? Foreflight comes pre-loaded with W&B models for common aircraft, but it would be easy for someone to accidentally choose the wrong model number of the correct type. More importantly, Foreflight explicitly permits individual users to e-mail W&B models directly amongst themselves; so sometimes the model being used is just from "some guy on the internet". Any of you who frequent various aviation forums will see this frequently. "Hey, anyone got a Foreflight W&B model for a BugSmasher 2000?" Again, not trying to pick on JWJR here - my guess is he's done the appropriate due diligence but didn't want to get into a sideband conversation about it. In summary, I think automated W&B tools like Foreflight, Excel spreadsheets, etc. are all great; and that it's completely "legal" to use them. But I expect pilots to have a rock-solid story about the provenance of the underlying data when I ask them about garbage-in-garbage-out risk. I can't speak for the FAA, but my guess is they take the same view.

Prior to some point in the model history (not sure when, but guessing all models before the M20J), W&B information was in a separate document called the "Weight and Balance Record". That's what I posted above. The "POH" for older model Mooneys is actually titled "Operator's Manual". You need both of these documents in the airplane to be compliant with the M20 TCDS. If you have only the Operators Manual, but not the Weight and Balance Record, the airplane is technically unairworthy. Note that having just a single sheet that records the empty weight and moment does not meet the requirement to have the Weight and Balance Record onboard. The latter document is the only place you'll find the graphs you need to compute the moments for passengers, luggage, etc.

Attached are a couple of files, though I'm not sure they're going to be that helpful to you. The first is a legible scan of the M20F "Weight and Balance Handbook". This generic document shows arms and stations for various standard and optional equipment, in that era. The second is a somewhat less legible scan of the actual weight and balance record for 1976 M20F S/N 22-1375 as it left the factory. It's a copy of the "Weight and Balance Handbook" with actual data for this particular serial number. Equipped with both documents, you can tease out the details of this particular airplane. The stumbling block is that if you look closely, equipment was installed in S/N 22-1375 at the factory, which is not in the list of optional equipment found in the generic "Weight and Balance Handbook". For example, there is no entry in the generic document for an "Alert 50 -- ELT", but there is an entry in the S/N 22-1375 original weight and balance record for that device. The original weight and balance record for your airplane almost certainly had similar equipment: things for which the factory knew the W&B info, but which is not listed in the generic W&B document. I suppose it's possible someone can send you an original W&B for an airplane that just happened to be identically equipped to your airplane, but that's probably a long shot. No harm in asking, though. weight_and_balance_record.pdf weight_and_balance_handbook.pdf

PM sent.

While one anecdote is not data, let me offer you some comfort. We bought our partnership Mooney in 2004. At the time it had about 900 hours on a 1991 field overhaul, so 13 YEARS prior! And not a name-brand overhaul, ours was a field overhaul at a no-longer-in-business shop in California, after a gear-up landing and prop strike. It's now 2021, engine is at 2200 hours and 30 years since that 1991 overhaul, and still running strong. Oil changes 3x/year at 30-40 hours on the oil, we always cut the filter and pull the pickup screen (a pain, but I'm getting good at it), and borescope the cylinders. There is some light scuffing on the cylinder walls, and compressions are down to low 70s, but other than some annoying oil seeps at the pan gasket and the spine, no issues. We don't use Camguard or do anything else fancy, but we do fly it regularly (75-100 hours/year), and we benefit from a dry climate. Near as I can tell, any IO-360 that's flown regularly seems to do well in the longevity department.

Yeah, at this point I wish we had the catch. The IPC page you posted lists two entries for item #85, which is the knob. The first is P/N 640282-007 for effectivity note "X" (see below), which is presumably the knob with the catch. The second is P/N #278 for effectivity note "XI", which is the smooth knob on our airplane.

No catch/button/friction lock on our airplane. Per the IPC, later models had a different knob, which is simple and smooth, see attached photo. This was taken before the adjustment, and you can see about 1/2" of exposed cable sheath with the knob pushed as far forward as it will go.