Vance Harral

I'd probably just use OBS mode off SIE and CYN - an old-school navigator mode for an old-school clearance. Looks like about 20nm between your turn points. Even at 180 KTAS that's plenty of time to set up the next nav waypoint.

GAMI spread has nothing to do with different EGT numbers between cylinders. It has to do with the fuel flow at which each cylinder reaches its individual peak EGT. In a well balanced engine with GAMIjectors, all cylinders should reach their peak EGTs within a few tenths of a gallon-per-hour as you lean the mixture. The value of peak EGT in any one cylinder may differ by 100 degrees from peak EGT in some other cylinder, but that is "uninteresting".

It might be the tach itself. But the nature of the max RPM adjustment screw for the prop governor is such that it does wear a little over time, and that wear can translate to a change in max RPM. At a point about 800 hours after prop governor overhaul, we found our max RPM to be about 50 off of the 2700 spec. Our mechanic made a small adjustment (half turn) to the set screw, and that fixed the issue.

Aircraft is a Mooney M20F, engine is a Lycoming IO-360-AIA. It's equipped with a Weldon 8163A electric boost pump (certified replacement for the original Dukes). POH start procedure specifies mixture to idle cut off, boost pump on to pressurize the lines, then advance mixture to prime. When the boost pump is turned on with the mixture at idle cutoff, pressure builds to about 25 PSI and is rock solid. The pump makes a fairly loud hum while it's on, of course, and the frequency of the humming noise (i.e. the speed of the pump) decreases a bit as the fuel line pressurizes. We don't prime for hot starts, but sometimes we prime when the airplane is "sorta" hot, e.g. sat on the ramp for an hour or two during a $100 hamburger run. Sometimes there is still vapor in the lines in these cases. If so, the pump seems to "strain" a little as pressure builds, and the frequency of the humming noise from the pump warbles a little. I've always considered this normal, during the 10+ years this particular pump has been in service. Now, after a recent annual, my airplane partner said he heard the hum from the pump warble a bit even on a cold start. This morning I turned on the pump for a cold start and let it run a full 30 seconds or so before priming. Sure enough, the speed of the pump varied a little after the lines were pressurized. Fuel pressure needle never wiggled, it was rock solid at about 25 PSI as expected. We're now trying to decide if the warbling frequency from the pump is "normal" or not. I confess I've never paid much attention to steady vs. warbling sounds from it, since I know some variation is normal as the lines pressurize (especially if vapor is present). The pump has about 10 years of service on it, and probably somewhere in the neighborhood of 2000 on/off cycles, so I suppose it's possible the brushes on the motor are going. It's also possible the system is sucking air from somewhere. There are no blue stains around the pump or gascolator upstream from it, that would indicate an obvious leak. But the bowl of the gascolator was R&R'd at the recent annual, to inspect and clean the screens. It was reassembled with new gaskets and safety wired, but that doesn't guarantee a good seal of course. What says the collective wisdom of the board? Leave it alone? Inspect the system? Replace the pump now even though it's not obviously defective? We're not necessarily trying to avoid the cost of a new pump. But we are reluctant to replace what may be a perfectly good pump, due to the risk of a maintenence-induced problem in the swap. Any/all opinions appreciated.

I'd guess it has less to do with location and more to do with battery type. You mention "good servicing of water", which implies you have a traditional wet cell battery. Everyone I know who is enjoying long airplane battery life (myself included) has a "maintenance free" recombinant gas battery. Typically it's the Concorde brand, though I think Gill has a competing product now.

It can be done, but there are many hoops to jump through. Suggest you reference this link on charity flights at AOPA's web site. The biggies are that as a private pilot, you must have at least 500 hours total time, and you must notify your FSDO in advance of the event. I've considered this several times, but never followed through. My take: if you want to make a charitable donation to the school, buy a gift certificate from the local flight school for a discovery flight and donate that (this is likely to be how the helicopter ride was arranged). If you want to take parents from the school flying, do that outside the context of the charity auction as nothing more than a friendly offer. I'm sad to say that for me, conflating the two things seems to be more trouble than it's worth.

One other thing... unless you have the one-piece belly mod, the panel you remove to access the limit switch isn't the same one you remove to get to the gear indicator bulb. Again, suggest you resolve any issues with the limit switch first before fooling with the bulb.

Larry, I doubt your bulb is actually burned out. That light doesn't illuminate until/unless the down limit switch we've been discussing closes. I suspect the same thing that's causing your gear warning problems is also causing the bulb;to not illuminate. If you do need a new bulb, it's a GE 330, which is very common and inexpensive (like two bucks). You can get them from Aircraft Spruce, Chief, etc, and maybe even your local auto parts store. That's if your maintenance shop doesn't already stock them, which is likely given how common a bulb it is. We've never replaced our gear indicator floor window bulb, and it has worked for over 10 years. I'm sure there's some LED equivalent that would work, but I wouldn't bother with it.

Assuming your system is the same as our '76F, the key component is a limit switch in the belly designed to sense when the gear is in the down-and-locked position. It's component 21EG07A in the schematics, and is a DPST switch. One pole controls power to the gear motor, the other controls power to the gear lights and warnings. If you're getting horns and lights while on the ground, it means the latter pole of the switch is not closing its circuit(s) for some reason. The switch is actuated by a tab clamped onto on one of the gear rods that runs through the belly. If your gear isn't binding up and popping the gear motor breaker when you extend it, then the problem is probably not the placement of the switch or actuator tab. Instead,either the warning logic pole of the switch is dirty/broken internally, or (more likely) the wires that connect to it are loose/dirty/broken. Suggest you start by removing the belly panel that allows access to the switch, identifying the wires that control the warning logic, inspecting them for breaks/chafing/etc. If there's nothing obvious, suggest you work with an A&P to loosen the nuts that connect the wires to the switch, clean the connections, and re-tighten the nuts. All the talk above about doughnuts and squat switches is useful, but only applies to the problem of not being able to retract the landing gear when airborne, due to the aircraft "thinking" it is still on the ground. That's the reason for the gear safety bypass switch. It allows you to retract the gear even when the warning logic "thinks" it's a bad idea. Concur with the poster who says it is a really bad idea to push that override switch any time you're on the ground. In my opinion, airplanes with a squat switch shouldn't have an override. If you can't retract the gear once airborne, that means something is wrong with the airplane: either the squat switch is broken/maladjusted, or you need to replace your gear doughnuts. For airplanes where the safety switch is airspeed based, I can see an argument for having the override, though it has pros and cons. Note that this switch is connected to the throttle and senses throttle position, not manifold pressure. The throttle position at which it engages is adjustable, and it is usually adjusted to some target MP. But because the MP you get for a certain throttle position can vary, so will the MP at which the warning switch triggers. As a silly example, the gear warning will sound if you put the airplane on jacks, retract the gear, and pull the throttle to idle, even though the MP will indicate about 30" due to the engine not running.

Even if the temperature of the exhaust gas coming out of each cylinder was the same, the EGT seen by the probe can vary with minor differences in the probe installation. The general consensus is it's not important for your EGTs to match across cylinders, only that each cylinder (ideally) reaches its individual peak EGT at the same mixture setting. I'm sure there are operators who have fine-tuned their setups to the point where an difference-between-individual-cylinder EGTs alarm can be useful, but I don't know any personally. In most cases it seems impossible to avoid nuisance alarms.

We installed a 650 about three years ago in our '76F (essentially the same panel layout as Bob's '77J, including the throttle quadrant), and we've been happy with it vs. spending the extra money to upgrade to the 750. Our #2 is a KX-155 as well. We've had no problems with it knocking out GPS reception, though I know that's been an issue in some installations. Bob, be aware that if you choose the 650, you won't be able to put it very high in your #1 nav stack. The steel tubing that comes down the center of the windshield continues below the glare shield, and prevents installing equipment of any significant depth up high. We wanted the 650 up high, immediately below our audio panel. But we wound up having to put in a spacer, then put the transponder below that, and push the #1 and #2 radios all the way down to the bottom of the stack. I was a little worried about the engine controls blocking the buttons on the KX-155 when everything is full forward, but that hasn't been a problem either. Here's a picture showing what it looks like: I'm used to the layout now, but having the transponder up top wasn't my first choice. The avionics shop said about the only way around that in an older Mooney is to go with the 750, which has an L-shaped profile with only the skinny display up top. The other Bob's comments about keypad entry, display of frequencies, etc. are spot on. These are mostly non-issues for us. I do occasionally wish we had the "full keyboard" for waypoint entry. I don't use the keypad for entry very much anyway, as I find it faster to use the nearest button and/or use graphical editing via touchscreen on the map. But even when using "nearest", it would be nice to see more choices on the page without having to scroll. About the only 750 feature I'm snarky about is approach plates. Sure, you can display them on the 750, but that's another high-dollar annual subscription, and even the 750's display is fairly small and low-res compared to any flavor of iPad. Three years into it, my personal opinion is that the 750 has about one AMU's worth of nicer features vs. the 650, but the actual price difference is still considerably greater that that. Your money to spend, of course, but I'm glad we saved our pennies for other toys.

Yep, this is a major annoyance to me, and one of the main reasons why we keep a now-ancient GPSMAP 396 on the yoke. I want terrain warnings, even if they are only "advisory" as opposed to "certified". And the only way to get them on the 650/750 is to pay for the TAWS upgrade. I don't know what's involved in the TAWS upgrade, but I have a suspicion it's literally just enabling a config register via a firmware upgrade. :-(

The installation instructions for the "fast response" flavor of P-110 specify 3/8" from the shoulder to the ferrule, which results in about an inch of the probe being inside the exhaust pipe. I'd guess this is sufficient for the "massive" flavor of P-110 as well, but I actually don't think it's a critical measurement. The round end of the probe that goes inside the pipe is just a housing. The thermocouple junction is inside that housing, and as long as it's inside the pipe, it should be fine. Sliding the probe further in/out of the pipe may vary the measured temperature a few degrees, but EGTs should be interpreted as relative rather than absolute numbers anyway. If it makes you feel any better, our probes are installed 4" down from the exhaust ports rather than the recommended 1.5", and that's not an operational issue for us. I hear you about the old style connectors. We had all kinds of trouble with them on one cylinder, and needlessly replaced at least one good EGT probe before figuring out the issue was wire breaks at the connector crimp joint, rather than the probe itself. EI sent us a bag of the new style connectors, which we installed on the EGT probe for the troublesome cylinder, and haven't had a problem since. I keep wondering if I should replace all the other old style connectors as well, but those have held up OK for whatever reason. My guess is the EGT installation on the troublesome cylinder experiences more vibration than the other locations.

I discourage pushing them on every walk around, as I think this tends to wear out the springs and seals (the only time our airplane ever failed a pitot/static check was due to a worn-out static drain). Certainly good to push them any time you think moisture might have gotten in the system - after rain, washing, etc. - and/or every few preflights just to make sure they haven't frozen up. If you've never fiddled with yours before, be sure to clean them before operating, as you don't want to push oil and dirt up into the mechanism. Provided they're clean, it's OK if they're a little hard to push in, as this usually just indicates the spring holding them in the sealed position is in good shape. Our static drain was very easy to push in when we first got the airplane. But a failed pitot/static test was traced to that drain being leaky. The replacement drain is much harder to push in, but no failed checks in the ensuing 8 years.

In a mode-C environment (most aircraft still do not have ADS-B out), the altitude ATC sees on their scopes is the pressure altitude broadcast by your encoder, adjusted for nonstandard pressure, i.e. the altimeter setting. Encoder altitude differs from true altitude due to (a) altimeter setting ( altimeter accuracy, © encoder accuracy, and (d) encoder resolution being limited to 100 foot intervals. Only (a) is common to all aircraft flying int he same atmospheric conditions. The others depend on the individual aircraft. To put some numbers on it... Altimeter tolerance is +/- 80' at 10,000 MSL, and encoder error is +/- 125' of the altimeter. Now assume you have a couple of aircraft using the same Kollsman window settings (call it 29.92 to simplify things). The first one is flying at an altimeter-indicated altitude of 9869', with an altimeter that reads 80' lower than true altitude, and an encoder that reads 120' lower than the altimeter. Its true altitude is 9869+80=9989'; but the encoder will broadcast a pressure altitude of 9869-120=9749=9700 with rounding; an error of 289' due solely to the state of the aircraft. Say the second one is flying at an altimeter-indicated altitude of 10080', with an altimeter that reads 80' higher than pressure altitude, and an encoder that reads 120' higher than the altimeter. The second aircraft's true altitude is 10080-80=10000', and its encoder will broadcast a pressure altitude of 10080+120=10200. In this case, ATC will "see" a vertical separation of 500', but the actual separation is only 20'. Even if the two aircraft talk to each other on the radio and say their (indicated) altitude, they'll think they are further apart than they actually are. Food for thought, especially for those of you who might see a mode-C-derived target on your TIS-B or ADS-B-in box, and decide it's no factor (or even worse, initiate an avoidance maneuver), without first visually identifying the target. FYI, we just got done with our biennial pitot/static/altimeter/transponder check, and I talked to the tech about this. It's tempting to think most systems are not right at the edge of the error tolerances, but the opinion of the tech was that edge settings are actually pretty common. One reason for this is the most common (i.e. cheapest) blind encoder has a very sensitive, single-turn pot for adjusting calibration. Once it's tweaked to anywhere within the 125' tolerance, techs tend to leave it alone and not try for better numbers, due to the likelihood of pushing it out of tolerance in the other direction. He also said the encoder does drift over time, and that there are plenty of scofflaws who let their biennial checks slide for months or years. Again, food for thought.

Sorry to hear of your trouble, Anthony. Wish I had parts to help you out, but don't know of any in my local area. When I found the cracks in our filler plates, I was afraid it was going to turn into a saga like yours. Fortunately the filler plates are more available than the backplate, and in our case Brian helped us out with servicable used parts. We took the airplane for its post-annual shakedown flight this morning, and all is well. Thanks again, Brian.

Including the "clamp to nothing" at the end of the housing? If so, that's really odd. Maybe that clamp just keeps the end of the housing from unraveling?

That might work if the clamp in question was connected to anything other than the cable housing itself. It's not, i.e. it's useless as installed, regardless of how it might be repositioned or reoriented. My guess is it's supposed to be attached to "something", and I'm trying to figure out what that "something" is. Again, the parts manual unfortunately doesn't detail the cable installation.

One bump in the hopes of scaring up a volunteer for pics. Maurader, any luck?

Thanks, Maurader. All this apparatus is on the co-pilot's side. The heating/ventilation reference page in my M20F parts manual says "1975 and on", so yours is theoretically identical to ours.

Attached are two photos showing where the cabin air vent cable attaches to the slider plate that opens/closes the vent, in our 1976 M20F. Closing the vent requires pushing the cable. As the photos show, our cable flexes a lot when the vent is pushed closed, because the clamp at the end of the cable housing isn't attached to anything but the housing itself. When it's cold and things get "sticky", sometimes the slider plate doesn't close when the cable is pushed in. I'm pretty sure this isn't how the system was designed, and that we're missing a bracket or something. The cable runs next to a huge bundle of wires, and I'm guessing it was R&R'd during some past avionics or electrical work, and not reassembled properly. Unfortunately, our parts manual doesn't detail this attach point, so it's a bit of a mystery how it's supposed to go together. Anyone out there with a 1976-ish vintage C/E/F/J who can take a picture and show/explain what it's supposed to look like?

PM sent, Brian, thanks. Appreciate the other suggestions, too. Fabricating a new one seem straightforward, but I'm not a metallurgy expert. Need to use same thickness, alloy, etc. Weight has to be close enough to be reasonably balanced until I can get the airplane to a prop shop for a fresh balance, which we're due for anyway.

Aircraft is a 1976 M20F with a Hartzell HC-C2YK-1BF prop. Annual inspection has turned up two separate cracks in one of the two filler plates in our spinner (see attached pic). This is not the spinner "bowl", just one of the filler plates that attaches to the bowl, behind the prop blades. As far as I know, the spinner is original equipment. Best as I can interpret the parts manual, this is the Hartzell 1904-3 spinner, with the associated filler plates being listed as P/N "A-2480". I found a Hartzell maintenance manual online which suggests certain cracks can be stop drilled, though I think ours may be too severe. Anyone stop-drill or otherwise repair a filler plate and care to offer advice? Alternatively, is this a good candidate for fabrication as an owner-produced part, using the cracked plate as a template? Best as I can tell, the filler plate is a simple piece of sheet aluminum, cut to a specific shape, with a few nut plates riveted to it. Seems simple enough, though not sure what particular flavor of aluminum alloy is appropriate. Last resort is to buy new, but I can only find reference to P/N "B-2480" in online sources. Does this supercede the "A-2480" filler plate? Thanks in advance for any advice/suggestions.

Thanks for the thoughts, all, I'll check out the alternatives. The 3M 5241 is even more expensive than the generic stuff from Spruce, though. The McMaster-Carr stuff is a tempting alternative, UV issues not withstanding. We get plenty of sun here in Colorado, but our bird is only outdoors when it's actually flying, so maybe/hopefully less of an issue if we just replace it every annual or two.

Our 1976 M20F has anti-chafe tape applied in the following locations: 1) overlap between empennage and empennage fairing, i.e. the interface that slides when the trim is operated 2) overlap between cowl edges and fuselage/nose stringers 3) interior of cowl where it rubs against the cooling baffles 4) edges of oil filler door 5) nose gear doors (I don't know why it's only on the nose and not on the mains) I confess I have no idea if these are "approved" or "recommended" applications for anti-chafe. The tape was there when we bought the airplane 10 years ago, and I've replaced bits and pieces of it over the years. I've always used "Teflon anti-chafe tape" from Aircraft Spruce for this: http://www.aircraftspruce.com/catalog/cspages/teflonantichafetape.php I like having the anti-chafe tape, but it gets ratty and annoying in a hurry. The only place it really seems to hold up well is on the empennage. Everywhere else, it peels away not long after installation, no matter how much I clean the application area (I've tried both mild and harsh solvents). I pulled it off the nose gear doors a while back because it wouldn't stay put and the chafing doesn't seem too bad there. But when I pulled it off the cowl/baffle interface a few oil changes ago, there was visible wear in the metal cowl surface by the next oil change, so I put it back. Now it's peeling off there and other places once again. I tried to research better solutions tonight, but there are a bewildering array of suggestions on the various forums: everything from very high dollar "aircraft" tape, down to plain old 3M tape from the "FAA/PMA section of Home Depot" (not that the "aircraft" tape is FAA/PMA approved anyway...) There's thin and thick tape, teflon and silicon, fiberglass reinforced, various adhesives, etc. The stuff you see on Aircraft Spruce, Chief, etc. is pretty spendy for experimentation, so I'm turning to my fellow Mooney drivers for advice. What are the rest of you using in the above listed areas, if anything? Thanks, VQ