Vance Harral

How exactly does the initial reporting for "appliances" work with ADlog? Do they give you a big list of possible appliances that might be installed on an M20x, and you check off what you have? Or does the form just say something generic like "list all your appliances, e.g. prop governor, radios, etc."? I freely admit I'm not an ADlog customer, so perhaps my skepticism is out of place. I just find it hard to believe there's much they can do in the way of knowing what appliances are installed on a particular 40+ year old aircraft, at least without sending out a genuinely knowledgeable representative to specifically inspect that aircraft. That inspection is a service I'd willingly pay for. But I already do - to my IA, who gets paid every year at the annual for his professional opinion on AD compliance, regardless of whether I use ADlog or not. He has his own software to assist him in that effort. But in the end, it requires a lot of collaboration between the two of us to get it (mostly) right. I get that ADlog has value outside this issue of appliances we're discussing. But I'd bet a lot of owners of older aircraft using ADlog have a false sense of security about ADlog informing them of "all" ADs that apply to their airplane. As an example, our airplane has Stan Protigal's STC for installation of an H3 halogen landing light. This is not a particularly well-known mod. My guess is it's not on any sort of checklist ADlog might send to a new M20F customer. If someone buys my airplane in the future and signs up with ADlog, how does ADlog know to watch for ADs on that landing light?

We had to do the same thing on our '76 M20F about 10 years back. We chose to just bite the bullet and buy the new rod/joint assembly. Looks like the cost has gone up a couple hundred from when we did it (doesn't it always?)

The first three are straightforward, but I struggle with the last, especially on a 40+ year old airplane. It's tough to identify what's an "appliance" and must be searched for separately. If there's an AD against your fuel pump, will you find it under M20 airframe ADs, or only under Duke/Weldon/etc. as an appliance? What about a landing light? Landing gear motor? Prop governor? Battery? Fuel computer? Radio? It's bad enough these things aren't typically categorized under the M20 airframe, but even worse when the one in your aircraft isn't a factory part, having been installed via a later OEM drawing, an STC, or other method of certification. One of the reasons I don't subscribe to ADlog or a similar service is they seem of limited value. It would be one thing if the vendor came out, did an extensive inspection on your aircraft, and used their skill and knowledge to build a one-off list of "appliances" to track for your aircraft. But my understanding is they put the entire burden on you/your mechanic, to identify and list all appliances specific to your aircraft. If you put in all the effort required to identify every appliance and list them by make/model/serial-no, you can search the FAA site yourself.

To clarify, the "eyeball" indicator has a fixed side and a moving side, both with horizontal white lines as you say. The vacuum lines actuate the moving side, which is essentially an indicator of how much force the system is applying to the elevator. In other words, the vacuum lines are an input to the indicator, driven by an output from the altitude hold unit in your tailcone. The (negative) pressure in the indicator lines is a down-regulated analog of the (negative) pressure in the lines to the elevator boots. The primary purpose of the eyeball indicator is to give the pilot information on what to do with the elevator trim when the system is engaged. If the indicator is consistently indicating an application of up elevator, the pilot should add some up trim, and vice versa. The goal is for the lines to match, most of the time. This indicates the most efficient trim setting, with the autopilot applying little to no elevator force in either direction. But note that when the autopilot is working, the indicator is constantly in motion to small degrees. You only adjust the trim if the average value is consistently above/below the fixed line. In our system (B-5 instead of B-6 but the idea is the same), I find the eyeball indicator to have mixed utility at best. First, I always trim the airplane for level flight prior to engaging altitude hold, so the indicator is mostly neutral most of the time anyway. Momentary changes in the indicator aren't very interesting - again, that's just a confirmation the pitch actuator is actually working. If the indicator is consistently high or low for an extended period of time, that means you've entered a very extended up/down draft, or that one of the boots is starting to leak. A trim adjustment is appropriate in those cases, but those are pretty rare events. More importantly, though, I don't think the indicator is intuitive at all. Imagine for a moment that you look at it, and the movable line is higher than the fixed line. What exactly does that indicate? Should you trim up or trim down to fix it? There's a correct answer, of course, but it's not obvious. My motivation to be really educated about the pitch trim indicator and other operational aspects of the altitude hold is hampered by the performance of our system to date. Our altitude hold "works", but performance is weak. We think this is a combination of two issues in our system. The first is the integrity of the seals for the tubing and valves associated with the altitude reference chamber. Ideally these would be perfect. In practice, they have a nonzero leak rate spec'd in the maintenance manual. What this means is that if your altitude varies from the selected altitude for more than a certain amount of time, the reference chamber establishes a new normal, and holds that new altitude instead of the one you originally selected. To prevent this, the system must be able to apply enough force to the elevator to correct altitude variances fairly quickly. That's our second issue. When we encounter an up/down draft, the system applies appropriate correction, but it's often too "soft". Before the system can return the airplane to the originally selected altitude, the reference chamber leaks enough to establish a new reference. We then have to disengage the pitch control, manually re-established the desired altitude, and re-engage. In smooth air this might happen once every 10-15 minutes, which really isn't too bad. In rough air - when you really want the altitude hold - it happens every couple of minutes. So often that it's arguably like not having altitude hold in the first place. We're hopeful performance can be improved by improving the reference chamber seals and/or increasing the gain on the elevator servos, but we haven't gotten around to addressing it yet.

@Danb, I wish I had good advice or good news for you, but we've dealt with the same problem for a number of years now - a very minor "hitch" that we are absolutely 100% convinced is caused by slight wear on the phenolic blocks where the yoke shaft goes through the panel. We band-aid it with frequent lubrications, and our A&P/IA is comfortable the aircraft is airworthy. But the reason we haven't installed new phenolic blocks is that best as anyone who has ever looked at it can tell (this is in a 1976 M20F model), the entire instrument panel must be removed to replace the blocks. It's easy enough to unscrew the fasteners that hold the block in place. But it can't slide off the back of the yoke shaft without removing a bunch of linkages and wiring, and it won't fit through the hole in the instrument panel such that it can be slid off the front after removing the yoke itself. We even purchased a spare block at one point from LASAR, but sent it back because we could not figure out any reasonable way to install it - at least not until some future, major avionics upgrade. My understanding is the problem isn't nearly as bad in other models. I hope yours is one of them.

@daver328, I don't recall that particular accident, but I'm aware of others like it. From balloons to drone operators to scud-runners, a lot of folks simply rely on big sky theory, and don't pay much attention to even simple rules, much less complex ones like right-of-way in the landing pattern. I respect your experience, and I especially respect your recognition that lots of experience sometimes causes you to be certain about things that aren't actually true, or used to be true and no longer are. When I asked for an FAR or AIM reference, I really meant it, as it's possible I'm mistaken too. Perhaps there are specific rules about practice approaches beyond FAR 91.113(g). But for now, my understanding remains that 91.113(g) is the only real governance, and that interpretation of that rule is nebulous in real life. After all, if it were crystal clear, there wouldn't be a need for all the industry articles written about this topic, the ACs, the endless forum debates, and so on. I think everyone here can probably agree on a few basic concepts: do your best to maintain situational awareness; don't be a jerk; and recognize that even good people can interpret rules differently or make honest mistakes. Negotiating traffic patterns - whether towered or untowered - is probably the most complex task the majority of civilian aviators engage in. It's a dynamic environment, requiring adaptability and judgment. I think it's great the OP and others like him post questions like this to stimulate discussion. but I long ago gave up on the idea there is a simple, well-understood answer.

Please let us know what CFR 14 regulation or AIM guidance requires this. If there is one, I need to learn about it. If there isn't one, you're just stating an opinion. Not one I disagree with necessarily, but still an opinion that many won't share.

That's certainly a reasonable and conservative idea. But I can tell you I'd feel bad if I reported a 6-mile final and you said you'd break off your base leg to let me land first. I certainly wouldn't take offense or feel you'd violated the spirit or letter of the FARs if you proceeded to land in front of me.

@toto, I get your point. But the first sentence falls apart in real life too, due to the nebulous understanding of "final approach", which is not formally defined in FAR 1.1. At what point does a landing aircraft transition from being "in flight" to being "on final approach to land"? Most VFR-only guys would probably say this happens on the base-to-final turn, but the OP specifically referenced the case of an aircraft on a practice instrument approach. I don't know the parameters at his airport, but the final approach fix for the GPS approach into my home airport is 6 miles from the threshold. No reasonable person thinks an aircraft on a practice approach here gets a 4-minute right-of-way (at 90 knots) upon crossing the FAF, vs. a guy who just turned base.

FAR 91.113(g): " When two or more aircraft are approaching an airport for the purpose of landing, the aircraft at the lower altitude has the right-of-way, but it shall not take advantage of this rule to cut in front of another which is on final approach to land or to overtake that aircraft. " That quoted, it's not always obvious who's lower, and the "shall not take advantage" clause leaves a lot of room for argument. I think of this one as akin to the automotive right-of-way rule for a 4-way stop sign. Which is to say that yeah, technically there's a rule for who goes first. But between ignorance of the rule, human nature, and measurement error, every case essentially boils down to appropriate use of judgement and caution.

My understanding is this was a legitimate, long-term reliability concern on radial engines, where multiple pistons apply pressure to a common crankshaft journal and bearing (e.g. for a 9-cylinder radial, 4.5 pulses per revolution. The practice of not letting the prop drive the engine stems from operating manuals for airlines, running engines like the R-2800, in very long descents at 300 KTAS speeds. John Deakin argues this is a non-issue with the typical flat engine used in the modern GA fleet (0.5 pulses per revolution). I don't know that he's right. What I am confident of is that it's a long-term issue either way, not an instantaneous one. There certainly is no harm in handling occasional events like a slam-dunk approach or emergency descent (real or practiced) by pulling the power to idle.

Don, can you expand your thoughts on this? John Deakin - who is on the APS staff - says concerns about the "engine driving the prop" in flat-4/6 engines are just as much of a myth as shock cooling. See https://www.avweb.com/news/pelican/186778-1.html

There's really not much to it, but ask and ye shall receive:

Mine came with a couple of mirror attachments included, but I found them to be low quality and not very helpful. In the end, I got really good images by simply bending the head 180 degrees around and safety wiring it tight to the adjacent flex cable. After doing so, the whole apparatus was still skinny enough to fit down the spark plug hole and look back at the valves. Picture attached below, note the slight angle on the flex cable just past the camera head. You need to bend a little angle there to look at the valves, as opposed to just looking back out the spark plug hole. Fair warning: the "WiFi View" app you download to work with the camera is pretty klunky. In particular, whoever wrote the app doesn't seem to understand the difference between resolution and digital zoom, and has unfortunately coupled them together. That's why the highest resolution image I posted above only shows part of the valve. You have to select a lower resolution to see the whole valve at once. But hey, whaddya expect for $40? I'm tremendously happy with the purchase. It's perfectly adequate for borescoping, and at that price it's essentially disposable.

And for grins, a little video of both valves in one cylinder attached below. Pics and video taken with a $40 wireless endoscope, available at Amazon: https://www.amazon.com/gp/product/B01MYTHWK4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 valves.mp4

You show me yours, I'll show you mine...

I guess I just don't understand how this happens, at least not "frequently". Seems like only a completely disreputable shop would behave this way, and that word would quickly spread not to use them. The shops I've worked with would call before doing any such thing (or at least that's what was specified in the written contracts I signed - in my case there was never any doubt the blades would be within limits after grinding). I only have an N of 2 prop shops, though.

This is a fair point, thanks for emphasizing that the type of propeller makes a difference. My purpose in giving the particulars of our propeller was just to put some actual data out there, vs. lore. I've met owners who are afraid to overhaul their propeller under any circumstances, because they're convinced it will almost always result in their blades being condemned. I think that's over the top, and not fair to the prop shops. One can certainly look up the service limits for a prop, compare them with the state of a single specimen, and reasonably estimate the likelihood of future condemnation assuming normal operations. Perhaps it's true the service tech I spoke with was "sticking his neck out" in giving such an estimate. But I like to think I convinced him I'm a reasonable customer and human being, not a simpleton who would interpret his statement as a guarantee of anything at all. As a person in the business, I'm sure you've dealt with customers of the latter variety, and I don't blame you for being conservative in your statements. We certainly appreciate your posts here on the forums. For what it's worth, I'm a fan of IRAN for props and other components, and would have preferred to do instead of having our prop overhauled last year. Unfortunately, I could not find a prop shop anywhere in Colorado at the time, that would agree to perform an IRAN on a prop with more than 10 years since the last overhaul. Faced with a choice between the risk and expense of a full overhaul locally, vs. the risk, expense and additional down time of shipping the prop out of state, we chose a full overhaul. I wouldn't criticize someone for choosing to ship out of state for an IRAN instead. It was a tough call for us.

Several posters have mentioned blade grinding. IMO, there's undue concern about this, if you're using a reputable shop. It's true an overhaul requires blade profiling, but the amount of material removed is very small - again assuming a reputable shop. Our prop was new in 1991. It was overhauled in 2005 (primarily to take advantage of the deal Hartzell was offering on new hubs), and again in 2016 (because it was throwing grease). So the blades have been reprofiled twice. At the 2016 overhaul, I asked how close the blades were to limits. The service tech said the prop was nearly guaranteed to make two more reprofilings assuming continued operation on normal airport surfaces, and possibly three. Given our history of about 12 years between overhauls, that means the blades will almost certainly be OK for another roughly 36 years, and maybe for another 48 years. I'm sure there are poor/disreputable shops that grind blades into oblivion for no good reason, but I don't really buy the argument not to overhaul your prop because it's likely your blades will be condemned. Just my $0.02.

Here are a few notes on the interior panels, from when we refurbished our interior (which has been almost 10 years ago at this point, hard to believe). Ours was a "poor man, DIY" refurbishment, not a professional job. Listing out items of interest, Anthony-style: Removal and re-installation of the interior plastic panels is best done in mild or warm weather, or in a heated hangar. The work requires a fair amount of flexing on certain panels, and if you do this when it's cold, you're likely to cause additional cracking. It's not necessary to completely remove the back seat to get the rear side panels out. Just unbolt the seat back at the top, where it bolts in to the steel frame, then fold the seat back forward, and slide the hole in the panel over the flange that receives the bolt. In our vintage of Mooney (1976 M20F), the overhead vent directors and top panels are blocked from removal by the knobs that open and close the vents. These knobs are held on with set screws, but the screw is behind (above) the vent mechanism. You need a bent wrench or angle driver to get to the screw, and you'll have to gently pry on the panels slightly to get to the screw. Also related to the overhead panels: when you finally get them loose, remember there are typically electrical connections up there (overhead light and sonalerts). There may not be much slack in the wiring, so be careful not to pull wires loose when the overhead panels drop. After removal, cracks in the panels can be repaired with fiberglass patches on the back side of the panel. With patience, some careful sanding, and paint, it's difficult to tell there was ever a crack in the first place. But it's critically important to roughen up the surface where you're applying the fiberglass patch. Otherwise the epoxy resin doesn't bond to the plastic, and the repair tends to "pop off" with the slightest amount of flex. Bends and ripples in the panels can be straightened by softening the material with a heat gun, then using vices and clamps to press and hold the material straight until it cools. Be careful, as there's a fairly thin margin between warm enough to re-form the panel and hot enough to melt the plastic. This procedure is particularly helpful to flatten out the divots that form over time where screws go through the panel. Based on various online recommendations, I initially tried high-end "Colorbond" plastic paint by Bryndana to paint the panels. I had a very negative experience, both with the paint itself and with customer service. I wound up using plain old Krylon "Paint for Plastic" from the PMA section of Wal-Mart instead, and it's held up well for a long time. It turns out the rubber edging sold in home & garden stores to cap steel landscaping strips makes a great replacement for the protective strip that goes around the edges of the panels that fit against the windows. If you really want the screws that hold the panels to tighten up, consider using a tool to flare the metal flanges that receive the screw (to give more purchase for the threads), then tap and drive a one-size-larger-than-OEM screw. If your airplane has a Brittain autopilot with vacuum servos, note where the vacuum lines run along the left side of the interior, and be careful not to drive screws through the lines when reinstalling panels. Much of the above can be avoided by simply buying new panels from Plane Plastics, but note that some fitting and trimming is typically required (remember these are hand-build airplanes).

The EI AV-17 is $250 at Aircraft Spruce: http://www.aircraftspruce.com/catalog/avpages/av17voiceannunciator.php You'll need a couple of $20 AVI-1 inverters unless you want to roll your own solution for the "high true" logic in a couple of the Mooney systems. With the addition of tax, that gets you up a shade above $300. But still very inexpensive in aviation dollars. We did the installation ourselves, our A&P signed it off as a "minor alteration". I'd be disappointed in any A&P who wouldn't do so on a part 91 piston aircraft.

We have an EI AV-17 voice annunciator in the airplane, and I consider it a great investment. Inexpensive and easy to install. It's not a fancy model with extra sensors or custom programmable warnings. It just has a number of input lines that trigger fixed messages, which you can connect to existing warning systems. We have it wired to the gear, stall horn, ram air warning, engine monitor, and vacuum. In my opinion, the value of a voice annunciator is both to get your attention for a warning you might have otherwise missed, as well as to clarify exactly what the issue is. For example, any of us on the forum for a while have seen multiple posts asking about the subtle difference between the stall and gear warning sonalerts in vintage models. Both emit the same note, just one is a continuous and the other an intermittent beeping. If you don't always remember which is which, that's a good argument for augmenting with a voice annunciator.

Flew from Longmont, CO to Torrington, WY this morning to catch the solar eclipse. Can't say enough about the great job the folks at KTOR did with this unusual event. Very well organized, plenty of parking, great hospitality. I didn't have a reservation, but figured I'd take off with plenty of fuel and just see how it went. Turned out to be a piece of cake getting in, and we had spectacular views of the eclipse. Not bad getting out, either. Departed about 1pm and we were sitting at home by 3:45pm, including a stop at the ice cream shop on the way home from the airport. My airplane partner drove with his family, and he's still on the road 8+ hours later (I owe him dibs on the next cool event!)

Brittain sells Mooney autopilot servos for about $200 apiece, my airplane partner got a quote just this week. My understanding is these parts are not brand new, they're refurbished cans with new rubber boots and seals (tape), that come with a yellow tag. Their inventory of these parts is limited, it waxes and wanes over time. In our case, it turns out they don't have all the exact make/models we need at this time, so we're going to have to pull our existing servos out of the airplane and send them in for overhaul. Overhaul of our existing units is going to run about $150 each. So cheaper, but longer down time while the parts are shipped back and forth. Had we been able to purchase the "new" units, my assumption is we could have sent the old ones in later for some amount of credit, but I don't know that for sure. My partner made the calls and I don't have the details.

Hmm... This makes sense, but I'm curious how the details work. It would be one thing to make trivial changes like swapping a resistor, changing a plastic fascia, etc. But putting a digital interface on an analog autopilot seems like the kind of thing that would have to be re-certified. At some point, a modification crosses the line from being a minor tweak to being a whole new product. That said, documentation from the manufacturer of the autopilot itself seems like pretty solid ground to stand on.