Vance Harral

We have a GTN-650 and a Brittain B-5 autopilot in our airplane. The system works well in NAV, TRK, and APPRCH (capture) modes. That said, understand the Brittain is just getting its information from the GI-106 CDI we installed with the 650, not directly from the GTN itself. The autopilot doesn't "know" it's talking to a GPS, it's just getting left/right track information from the analog voltage output of the CDI. Really no different than when the CDI is receiving a VOR signal in VLOC mode. Your current setup almost certainly works the same way - the autopilot gets information from the CDIs your KNS80 and KX155 drive, not directly from the radios themselves. My understanding is it's possible to install a GPS roll steering computer such as the DAC GDC31, and interface it to the Brittain. With this setup, you put the autopilot in heading mode, and the roll steering unit computes headings for the autopilot to fly, which result in it tracking the desired course. This allows the autopilot to fly course reversals, holding patterns and other complex courses. It's a nice feature, but not one we've been motivated to pay for. I don't think a G5 indicator set up for HSI mode has traditional analog voltage outputs that can directly drive an autopilot, like the GI-106 and other CDI indicators. My understanding is you can't interface the G5 with an autopilot unless you purchase the forthcoming GAD29B interface unit. That unit is not yet certified, and the list of legacy autopilots for which Garmin intends to pursue certification doesn't include Brittain.

Test results like this are one of the reasons we switched to Phillips XC20W-50 from Aeroshell 15W-50. It's the cheapest option in these parts, and while I have no problem paying more for actual higher quality, there's no reason to pay more for clearly equivalent results. The other reason we switched is the issue mentioned in the Blackstone report about additives in Aeroshell reacting with the copper flashing on the camshaft and causing high copper readings. We saw that in our oil analysis. The higher copper from this is harmless in itself, but my thinking is it could mask copper wear from other components.

For what it's worth, our access hole is in essentially the same place as Chupacabra's. We're a little luckier in that the alignment is a little better. But as you can see in his photos, there's plenty of room to angle the screwdriver a bit if the alignment isn't perfect. The real trouble is figuring out which direction the screw is off from the hole, without removing the cover in the first place. You can shine a good flashlight through the slot for the throttle lever, and peer through the hole itself to locate the screw. But it does require standing on your head (or at least lying across the passenger seat with your feet out the door) to look. My recollection is that the adjustment screw is ferrous, and will "catch" a magnetic-tip driver. But it's been a long time, I wouldn't swear my life on that. If I really had trouble with it, I might consider using a step bit to enlarge the hole.

Per the M20 TCDS, the M20E was certified to CAR 3 standards, while the M20J was certified to CAR 3 plus a bunch of specific items from FAR 23. FAR 23 requires certain data be published in the POH. My guess is that's why the M20J and later models have published demonstrated crosswind components, while earlier models do not. The fact the M20E POH doesn't have a max demonstrated crosswind component doesn't mean one wasn't demonstrated - the CAR 3 standards require a max demonstrated crosswind component of at least 1.2 Vs0. It's probably published "somewhere". However, it doesn't matter if you know it or not. It's not a legal (or practical) limit for GA airplanes certified under CAR 3 or FAR 23 and operated under part 91. Even in an M20J, it's not illegal or impractical to land with a crosswind component in excess of the max demonstrated crosswind component published in the POH.

We've had pretty good luck with a RAM X-mount (http://www.rammount.com/products/x-grip) attached to a suction cup and extension arm (http://www.rammount.com/part/RAM-B-166-103U). The Stratux and its case with antennas sit in the mount, and we run a USB cable down to the battery, which sits in a pre-existing pocket on the sidewall that holds the POH. As you probably already know, it's crucial to get the antennas out from behind the airframe. An external connection like @Skates97 rigged up is best, but barring that, on the glareshield or against a side window seems adequate. We initially just put ours on the back seat or the hat rack, but that turned out to be mostly useless.

That's a fair question. The honest answer is, I don't actually know. All I know is it was there when we bought the airplane. No modification logged in the logbooks, and it looks "professional", so I've always assumed it was OEM. It's entirely possible it's just a well-crafted local mod by some clever A&P.

Not necessarily. In our 1976 F, there's an access hole in the quadrant itself, through which you can poke a screwdriver to adjust the trigger point.

I spent some time searching on this, and I can't find any specifics on the display glass used in the Garmin and Avidyne touch screen products. Not sure what you mean by them "feeling" more fragile, perhaps it's a personal perception. They're certainly not made of plastic.

Glass on touch screens isn't fragile or scratch prone, and those "screen protectors" are almost always unnecessary. It's not impossible to scratch it, but you're certainly not going to do it with the casual application of a fingernail or plastic pen cap. For reference, your fingernails are about 2.5 on the Mohs' scale. A copper penny is 3, soft steel is about 5. Window pane glass is about 6, and things like the Corning Gorilla Glass found on most modern touch screens are nearly 7. As a practical example, I've carried keys and/or change in the same pocket as my phone on occasion, with no damage to the display. To be fair, some displays have an anti glare coating on top of the glass that can get scratched, and deteriorate over time. My Garmin 396 portable had this problem. I fixed it by taking rubbing compound to the screen to polish off the coating, then putting an anti-glare "screen protector" over the display. The purpose of that was just to restore the anti-glare properties, not to "protect" the display glass itself. To my knowledge, no panel-mount GPS/NAV/COM has this kind of anti-glare coating, so not a concern. I also think if we're going to discuss people using things other than their finger tips to point at or actuate controls, it's fair to argue the plastic or rubber face of a hard key is more fragile than touch screen glass. None of this is meant to be argumentative toward pilots who just simply like knobs and hard keys. Personal preference is just that, personal. But I do think there is a long-term reliability component to consider. Hopefully this discussion is helpful to the OP.

I tend to hang on to my gizmos a little longer. My iPad is about 5 years old, and my phone was even a little older than that, until I swapped it out this year for my son's hand-me-down iPhone 6. Never seen a touchscreen failure. Heck, even phones that are abused to the point of cracking the display glass still seem to work fine (other than the glass shards in your finger). I've seen plenty of people just plaster a screen protector over the broken glass and keep on truckin'. My son lived with this for about 6 months until we bought a replacement digitizer/display unit for his phone. That said, I think hours of use has as much impact as calender time... I'm pretty sure in three years, the average phone sees a lot more use/abuse - including exposure to the elements - than a panel mount navigator in an airplane. Again, I don't have any scientific data, but my anecdotal observations sure suggest the touch screens are more robust. Your experience with your 430 buttons is common. Sure, you can get them to work again for a while by exercising the buttons, but it's not going to get any better. The real, no apologies fix is to send it back to Garmin for their $1000 flat repair rate. I agree flight school airplanes see more use/abuse, but GNS button failures aren't specific to unloved/high use airplanes. My buddy with the flaky 530W takes as good care of his airplane as anyone. Low time, always hangared, etc. I'm sure you take good care of yours too. It's not just a flight school problem. Here are a collection of threads I found in just a 60 second search, from people with 430 button problems, none of which involve flight school airplanes: http://www.vansairforce.com/community/showthread.php?t=94227 https://www.beechtalk.com/forums/viewtopic.php?f=21&t=113739 https://www.pilotsofamerica.com/community/threads/can-you-clean-430-buttons.47091/

Having flown hundreds of hours with both hard knobs/dials and touchscreens, I continue to be mystified by this criticism that touchscreens are "difficult" in turbulence. I find both systems easy to use in smooth air, and slightly more difficult to use in turbulent air. I'd wager people that have significantly more trouble with a touchscreen in turbulence aren't using the bezel to support their hand when tapping, maybe trying to hover their whole arm up over the panel. Some touch screen devices have better supporting edges than others. The bezel on the GTN series is specifically designed for this.

One of the trade-offs to consider is long-term reliability. Every nav/com gizmo I've ever used with knobs and hardkeys seems to eventually flake out: KX-170, KX-155, Garmin 430, Garmin 530. I've used numerous copies of these radios, and after a while the knobs and buttons slip or don't register. The 430 on one of the local flight school airplanes has one of the hard keys held in with tape. A buddy with a 530 is starting to have trouble with all the hard keys on it. The 50/25 KHz pull knob on our KX-155 has been flaky for a while, etc. Touch screens have failure modes too, of course, but my own personal experience with phones and GTN devices suggests they hold up better to long-term use. I don't have any scientific data, just my opinion.

My impression is the failure isn't all that uncommon. We've had it happen twice in 14 years of ownership. Little more oil than usual, discover compromised main seal when pulling the cowl and feeling behind the prop. I know it's scary to think all the oil could drain out in flight. But the prop flange end of the crankshaft exits at the top of the case. Assuming you're not flying aerobatics, the only oil that will blow out there is little droplets from splash lubrication. Even if the seal completely departs, I don't think it's likely to be an OMG-I-coulda-died failure. It's certainly not the same as losing your oil drain plug, or blowing a hole out the bottom of the case with a thrown rod. I'm not trying to water down your concern, though, just explaining why the main seal mechanism likely isn't more robust to start with.

These GPS Interference Testing NOTAMs have been issued on a regular basis in the southwest US for years. Not once in that time have I ever actually seen a loss of GPS signal. Note that the center ring says interference "may" occur down to 50' AGL. That's essentially all the way to the surface. Can you imagine the howls of indignation if GPS actually quit working for all the surface vehicles in that 184nm radius? Every phone running a street nav app? Loss of tracking on every taxi and UPS truck? I don't have any insight into what agency does this interference testing or how it works. But my guess is they have a transmitter on which they carefully increase the gain, until it just barely begins to interfere with GPS signals - measurable, but still well within parameters to allow commercial receivers to be essentially unaffected. My guess is the NOTAM is there in case of a mistake, not because they really think any commercial receiver will lose signal. It's just a guess, but I think any actual, significant interference is a rare mistake. Again, I've never once observed loss of signal on the ground or in the air, on many affected dates over years of these NOTAMs being issued.

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.