Vance Harral

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

True of all modern thermocouple instrument designs, including every all-cylinder engine monitor on the market today. But some ancient instruments employ a needle movement which depends on current driven through the wires by virtue of the voltage induced at the thermocouple junction. On those designs, the length of the wire matters, because the needle movement is calibrated for a specific current bias based on the resistance of the total wire length. I've never seen such an instrument in person, even on some pretty old airplanes. But they did exist, and are the source of the admonition not to cut thermocouple wires. It's possible your helper is confused about this, but more likely he was just trying to save time. A lot of engine monitor packages are sold with the probes pre-wired, i.e. they already have connectors soldered at all the interfaces when they come out of the package. Shortening the probe wires in this case requires splices and/or resoldering the connectors. It's easier to just tie up the excess where convenient, and call it a "service loop".

Recommend you call Aviall too, and price compare vs. PHT. Either is fine, I'm sure. For reference, we bought 4 PTFE oil hoses with integrated fire sleeve from Aviall a couple of months ago (two for the oil cooler, two that feed the oil pressure gauge). Total cost for hoses alone, not including labor, was about $750, most of that for the larger diameter oil cooler hoses. I'm aware you can make them yourself for much cheaper, but we didn't want to DIY it, and we were a little uncomfortable with the idea of re-using fittings.

OK, I'll bite. Not sure how "typical" it is, but this is a 1976 M20F (very similar layout to a 'J') with a pedestrian 6-pack, but fairly modern gear in the radio stack.

Thanks Brian, I'd forgotten about the bypass mechanism. Makes sense.

I've never really understood what the magnets are supposed to accomplish, can someone explain? Are there particles small enough to pass through the filter media and re-enter the oil system, but large enough to be "caught" by the magnets? Or do they just eliminate the extra step of sawing out the filter media and spreading it out to look for particles when you do cut the filter?

In the electric gear airplanes, the emergency extension system just turns the same shaft the electric motor ordinarily turns. If a failure to extend is caused by a problem with the shaft, rods, or gears internal to the actuator, that single failure kills both the normal and emergency extension mechanism. This is the reason why the landing gear actutor ADs/SBs are so important to comply with.

Not sure what is meant by this, as there can be no shower of sparks if the vibrator is not enabled (other than aftermarket mods like Slick Start). Even with the vibrator enabled, there isn't any actual sparking at the plugs until you crank the engine, such that the LR points in the mag open and close. For those interested in how the SOS system works, here are a couple of good links: http://www.donmaxwell.com/publications/MAPA_TEXT/Shower%20of%20Sparks/Shower%20of%20Sparks.htm http://www.aeroelectric.com/Mfgr_Data/Magnetos/Continental_Motors/IGN-52_Shower-of-Sparks_TM.pdf

Respectfually disagree. The question was whether the SOS engages with twist only vs. twist-and-push. To answer this, you need the Mooney schematics for your airframe, to determine how the switch is supposed to connect the starter vibrator. In later models like mine, the BO enable pin of the vibrator connects to the BO terminal of the switch. In older models where the SOS engages with twist only, it's connected to the S terminal of the switch. There no way to know this without the Mooney schematics, the switch spec alone is not enough. Things are complicated by the fact that the spec sheet you linked to covers multiple models of switch, as well as the fact that many Bendix parts have been superceded by later TCM switches. In particular, the PUSH TO PRIME rows in your table apply to a flavor of switch that's different from the PUSH TO START flavor installed in the C/E/F models.

Can't speak to other models, but the POH for the '76F wouldn't help you with either of these questions. The normal starting instructions just say, "turn to 'START' and push forward", which gives no clue about whether the SOS is enabled by the first or second action. There are no procedures for hand-propping in the POH either. In fact, it specifically says, "Hand cranking is not recommended". The only way I know our switch is wired as designed is from a combination of the aircraft schematics, and the technical documentation for the mag switch itself. I know people have hand-propped Mooneys with SOS systems, but using a switch with separate SOS vs. crank connections always seemed like a dicey proposition to me. It doesn't take much of a slip by the person manning the switch to engage the starter while intending to engage only the SOS. It's safer to disconnect the starter first, in which case it doesn't matter which position enables the SOS. I'm sure somone will jump in and say you wouldn't be hand-propping if the starter could turn over the motor in the first place. But if the battery is *completely* dead, it won't run the SOS either. So there is no point in hand-propping unless you have at least some energy in the battery - i.e. not enough to crank, but enough to change the dynamics of hand-propping if you slip on the switch. When you combine those risks with the tricycle gear configuration of the Mooney, and add in the slightly higher compression of the 200-hp engine in the later short bodies, it's not hard to understand why Mooney would remove hand-crank instructions from the POH. My guess is the change in ignition switch wiring happened around the same time.

No. Not all models are wired the same, our '76F is wired exactly the same as yours: SOS doesn't come on until switch is pushed in. I do think "most" Mooneys are wired so the SOS comes on when the switch is turned against the spring. But it's incorrect to extrapolate that to all models.

Maybe. But I advise people to be cautious about buying into a partnership where the person offering the deal is currently the sole owner, even for a little while. Not that they don't mean well, but sometimes it's difficult for a sole owner to accept truly equal ownership of new partners, especially when it comes to all the little things: fueling policy, whether the belly gets wiped down after every flight, if the sun shade gets put up, is the strobe/beacon switch left on or off, etc. Emotionally, some folks think of it as still being "their" airplane, which they're just letting the other guy(s) use, as opposed to a genuinely shared asset. Not really suggesting the OP shouldn't proceed with buying an airplane, but just some food for thought about how it's treated while finding new (or old) partners.