Vance Harral

I had good luck cleaning up my wheel wells with the local shop's solvent pressure washer (basically just an engine degreaser), and a variety of scrub brushes of different shapes (be sure to get at least one skinny, pointy one). That said, you need to be careful, even with low-grade solvents. I accidentally laid down in a puddle of the stuff for a few minutes, leaving a rash on my back even through a heavy denim shirt. Worse yet, I managed to get a few drops in one of my ears, which was quite painful and dizzying. I didn't win any safety awards that day...

It's more likely to be the probe, but don't guess, determine for sure before buying any replacements. Once you've identified which system is bad, you can test the probe for that system by measuring it with a multimeter. The first test is to measure the resistance, which should be "relatively low" (not open circuit). If that checks out, you can measure the voltage (for thermocouple probes) or resistance (thermistor probes) output when the probe is in the hot water, and compare against expected values in tables you can look up on the internet. If the probes seem OK, you can check the gauges by applying a voltage or resistance across their leads, but that's a little riskier: it's possible to ruin the instrument by applying inappropriate inputs to it, so only do that if you're fairly confident you know what you're doing.

The traditional way to look at this is to remove the probes from their bosses while leaving them connected to their respective instruments, and drop them in a pot of boiling water. Whichever one is wrong will be way off from 212 degrees.

Actually it's even more complicated than that. The orientation of the filler neck is different in different Mooneys, such that different filler caps have a different orientation of the 3 "ears" to get the tab pointed to the rear. If you buy a replacement cap off E-bay that looks right, without checking the exact part number, you wind up with a cap that has a caddywhumpus orientation. Ask me how I know...

Can't speak for others, but as a CFI, I wouldn't fly the airplane with you unless the issue was either resolved where it is, or by getting a ferry permit to take it somewhere to have the work done (which would be pretty straightforward to obtain). The reason I wouldn't fly the airplane isn't because it's "dangerous". Rather, as an instructor, it would convey the wrong impression - that bending the rules is OK when you think it's "reasonable". Students learn as much or more by your actions, as they do by your words.

Flying the airplane as currently equipped is a (small) legal risk. The actual safety risk is effectively zero in my opinion, but that's a separate subject. The assertion that "no one" can fly the airplane until the issue is resolved, and your questions about it being "grounded", make it sound like you're considering using inappropriate leverage against the seller. e.g. trying to prevent him from saying "no thanks" and flying away from your offer by intimating you'll involve the FAA. Hopefully that's not what you're getting at. This is an airworthiness issue per your purchase contract, so by all means negotiate on price to have it resolved. But as Anthony says, it's a relatively small and likely inexpensive issue in the grand scheme of things. And if you're considering trying to get the mechanic or FAA involved... don't be that guy.

The attached photo isn't my airplane, but was a convenient image on which to draw. Our intercom jacks are mounted in the front edge of the arm rest "cutout". This is different from the location in RLCarter's photo, where they're in the armrest ledge itself. The orientation of the jacks is horizontal rather than vertical, which I think makes them a little less prone to being knocked around. In the photo below, there's another indentation in the panel forward of the armrest, where the jacks in this airplane are actually located. Our interior panel doesn't have that indentation, hence there is room for the jacks to be mounted in the "cutout".

You're correct, and I stand corrected, thanks! I didn't dig deep enough to find this cross-reference, I was just searching the TCDS for "CHT", cylinder head", etc. It's interesting that CAR 3 "required basic equipment" lists a CHT gauge as required, whereas FAR 91.205 does not. I wonder what the history of that change is.

If the airplane lacks a required instrument, it is not airworthy and cannot be legally operated. But, it's not the responsibility of an A&P to "ground" the airplane. That's the responsibility (and risk) of the owner/operator. A mechanic can decline to sign off an annual, but he has no legal authority to prevent operation of the aircraft. It's essentially the same as an auto mechanic observing that your car lacks required emissions equipment. They can make note of it and/or refuse to work on it, but they can't prevent you from driving it home.

Then as far as I know, there is no requirement for such an airplane to have a functioning CHT gauge. It's not in a POH Limitations section or in the type certificate. Here's a link to the M20 type certificate, which is inclusive of all M20 models including the M20C: http://www.airweb.faa.gov/Regulatory_and_Guidance_library/rgMakeModel.nsf/0/60107bc8954c93a686256c24005b5075/$FILE/2A3.pdf Nothing in that type certificate requires a CHT gauge (or ammeter). It would be interesting to ask the A&P what his basis is for saying the CHT is "definitely required". You should make sure he's not confusing an early model M20C with a later model M20C which has a POH with a Limitations Section which calls out the CHT as required equipment.

As RLCarter said, 91.205 isn't the only place you have to look. Either the FAA-Approved "Limitations" section of the POH, or the Type Certificate for an aircraft can specify required equipment beyond that listed in the FARs. If they do, the listed instrumentation is required to be legally airworthy. The "1976-78 POH" available for download here has such a Limitations section, which lists the CHT gauge as required equipment (ammeter is not listed). However, earlier M20C POHs have no such Limitations section. So I believe the legal requirement depends on the year model of the M20C you're looking at. You need to get the actual, official POH for that aircraft. If the CHT gauge is listed as required equipment in an FAA-Approved "Limitations" section, the airplane is not legally airworthy as currently equipped. As others have said above, the UBG-16 is not certified as a primary gauge replacement. Post #3 says the EGT probe and gauge was removed, not the CHT probe and gauge. ragedracer1977, If you need to address this problem, you'll have to install the original CHT probe and connect it to the factory gauge. Then, assuming you want your UBG-16 to still track the #3 CHT, you'll need to order an EI "piggyback" probe which allows both the factory probe and the EI probe to sit in the thermal well boss of the #3 cylinder. Agree with others that the seller should pay for this if the CHT gauge is legally required for airworthiness.

Are you sure about that? I've never seen a Mooney maintenance manual that specs anything about "travel when the aircraft is suspended". As far as I know, every maintenance manual spec on the shock disks specifies having the aircraft on the ground, with full tanks. Respectfully suggest you double-check. As others have said above, if you have 0.25" of play when the gear is first retracted on the jacks, there's a good chance you have more than 0.60" of compression when the weight is on the wheels.

No wonder the fly-in suggestions are never near me, here in Colorado. C'mon, where are all you middle-of-the-USA Mooney drivers?

That's probably about right at current prices, but the darn things seem to inflate in cost about $5/disk per year. The first time I ever looked into it (over a decade ago), you could find 'em for about $80 apiece. Next time I looked they were $95, then $100, then $105, etc. We replaced our mains at annual this year and paid about $115 each. Moral of the story: if you think they're getting close, just replace 'em now. They'll probably be more expensive next year.

Factory specifications for shock disk replacement should be documented in the maintenance manual for your airplane. I have a 1998 M20J maintenance manual, and the relevant details are in Section 32-81-00. No jacking is involved. The procedure is to leave the airplane on the ground, fill the tanks, and measure the gap between the retaining collar and the top retaining plate. Basically, you're measuring how much the disks compress with weight on the wheels. The allowable gap is 0.60" for the mains, and 0 (no gap) for the nose. The amount of play after jacking, how long it takes the disks to uncompress, the date code on the disks, etc., are all reasonable things to consider. I don't have any particular beef with mechanics using those factors to recommend replacement. But that's not how the factory spec'd it.

I'm in, link please. Profile says Erie, CO which is where I live, but airplane is actually at KLMO, not KEIK.

As a fellow M20F owner, I'd suggest there's little reason to pay the extra cost and weight penalty for the 35AXC. We've been running the 35A model for over a decade with zero problems. First one lasted 8.5 years and was still "usable" when we replaced it, just starting to show very early signs of reduced total capacity. Bought another which has been running strong for 3.5 years. Aircraft lives in Colorado, near Denver, and sees occasional days above 100 and below 0. We don't use a battery minder or anything similar. We do fly frequently, but the airplane occasionally sits for several weeks, and has always fired right up. Finally, some people report having to modify the top of the battery box to fit a Concorde battery, but we didn't need to do so for the 35A. Based on my experience, the extra cold-cranking capacity of the AXC is irrelevant for an IO-360-AIA engine. The AXC does give you 17% more total capacity, which theoretically gives you 17% more time with electrical power if your alternator gives up the ghost. But the scenarios where that would matter are pretty far into the corner cases.

One way to deal with this sort of thing is to bill a wet rate instead of using a dry lease, based on the cost per gallon at the home airport and typical fuel burn. In this case the company always reimburses for fuel purchases, rather than only when the top-off rule isn't followed. There is a tiny amount of "unfairness" in this due to variations in actual gallons-per-hour used by different operators, but it's trivial. In exchange, administration gets a lot simpler. In particular, it makes it easier to deal with situations like the fuel pump being closed, or the case where operator #1 asks operator #2 to leave the tanks down a bit because the next flight is going to be heavily loaded. The operators already have money going into and coming out of some sort of escroe account to pay the dry rate, so it's really no more overhead to deal with fuel reimbursements at the same time the flight is "billed" - just have everyone clip fuel receipts in the same logbook you use to track tach/hobbes time. We've run our partnership this way for a long time and it's worked well.

Your pointed reply with boldface type nicely illustrates the point I'm trying to make. Saying these pilots are not partners due to their lack of an equity stake makes it clear you don't see them as equals. They're just "renters" to you. No matter how nice and/or experienced they are, if you treat them like renters, they'll treat your airplane like a rental. You need to be OK with that. Some renters are better than others, of course. That judgement call is up to you. To be clear, I get that you're the only one with capital investment, and it's not unreasonable to want more/all of the control because of that. Adults are free to enter into any honest agreement, and I'm not saying your arrangement can't work. I just think it's uncommon for arrangements like this to work well over the long term. People who don't want to pay for an ownership stake usually discover it's better to rent from a business with no emotional investment in the rental machine, even when that comes with per-day rental minimums, etc. I have seen the arrangement you're proposing work out OK when the "renters" are actually aircraft owners themselves, who just want occasional access to a different type of aircraft. Usually it's reciprocal. Any chance your renters are aircraft owners themselves, or at least have been in the past? If so, that probably improves your odds of a good long-term arrangement.

For those of you interested in water ditching strategies, the following is a good read: http://www.equipped.org/ditchingmyths.htm It's the only research I'm aware of where someone actually tried to look at NTSB records and determine what strategies and situations matter. Among other interesting points, the author contends there is no data to suggest ditching with wheels down (or in fixed gear airplane) makes any measurable difference in survivability vs. wheels up. He also says skill, planning, and preparedness for ditching don't seem to matter much either - student pilots with little experience and no knowledge of "recommended" ditching procedures tend to do as well as the Gray Eagle Ace-of-the-Base.

If you really trust your potential partners and believe everything is going to work out, give them equal scheduling rights, and equal say in how the aircraft is operated and maintained. Trust that they'll treat you fairly about scheduling. Ask what they think should be in the operating agreement and incorporate their ideas. If you're unwilling to do these things, I predict a negative outcome. I've been part of a successful partnership for 14 years and I know it can work out well. But I wouldn't enter a partnership where one person wants a greater share of privileges and say-so in aircraft operation because the airplane is more theirs than mine. I understand you're carrying a greater share of the capital investment and responsibility in exchange for it, I just think it's unlikely to pan out when some of the pilots are second-class citizens. Not because it's "unfair", just due to human nature. Ask yourself, if one of your friends dings a wingtip or spills orange juice on the seats, is it no big deal because these things happen and it's just a machine, or are you going to be irritated at their carelessness with "your" airplane? The answer to these questions has a lot more to do with the success or failure of the partnership than the rental agreement. The agreement is important too, but it's secondary to the attitude with which you're going into it.

Sorry you had a bad experience, we've had zero trouble with ours in the 7 years it's been installed. That's just one data point, though. There are certainly opportunities for things to go wrong with it.

I wired ours to the terminals of the sonalert, rather than the stall sensor itself. Saves running a set of wires out into the wing.

Something about that doesn't seem right. Assuming $100/hour labor, that's 50 hours - more than a full week. I try not to cry "inflated mechanics charges!" without understanding details. Was there something complicated about your installation? Other work done in addition to the AV-17, or maybe a bunch of old wiring removed? By way of comparison, I did the wiring myself and had the mechanic inspect it. Total cost, about $350 for the hardware, plus one hour of labor for inspection and sign-off. The work is mostly just adding wires to existing connections via screw-on ring terminals, no soldering involved. It does help to have a firm understanding of electrical behavior, to understand where an AV-1 inverter or equivalent is needed. As an amateur working very slowly, it took me a couple of days to do the wiring. That doesn't include the time to study the Mooney system schematics and fully understand the AV-17 manual, though. I'd like to think a decent shop would already have that knowledge or at least not charge you for their learning curve, but maybe that's debatable. I completely understand that some folks don't enjoy the DIY approach. But even turning the whole process over to the shop, I would have guessed $2K total cost at most.

Probably not the issue, but to scientifically complete the experiment, you'd need to perform stalls at altitude in your normal landing configuration (which you said is usually full flaps, occasionally partial). In your original post, you said the stall warning came on at 70 KIAS in the "no flaps" configuration while airborne. The indicated airspeed at which the stall warning horn will come on with flaps extended is slower. But only by a few knots. I did read where you said you make full-stall landings and agree it's odd you're not hearing the sonalert on landing. Absolutely. One of the best and least expensive upgrades we made is the addition of an EI AV-17 Voice Annunciator to our airplane. In addition to the factory sonalert tone (which I agree is easily missed), we now get a "check airspeed" warning through an always-on feed into the audio panel. It also generates voice alerts for the landing gear warning, engine monitor alarm, low bus voltage, and low vacuum. My mechanic was willing to sign it off as a minor modification.