Vance Harral

Another technique for slowing down and staying within the confines of a small practice area is to add drag via steep turns. Cruise to the practice area, reduce power, make clearing turns as necessary, then roll in and put on some "G"s to slow down. The Commercial ACS standard for steep turns is "approximately" 50 degrees of bank, which is 1.5G of load factor assuming level flight. Salty old flight instructors will sometimes ask for commercial steep turns at "59 1/2 degrees" of bank, or about 2Gs. Anything in that range will slow you down pretty well through a 180- or 360-degree turn, and is an excellent demonstration of the drag associated with steep turns. I add the usual safety disclaimers here: clear for traffic before maneuvering, be mindful of the increase in stall speed with load factor, etc. But since the Commercial Certificate requires a greater degree of proficiency in steep turns anyway, it's not an unreasonable technique.

ACS = "Airmen Certification Standards" - the document which governs FAA flight tests. It's an evolution of the old PTS ("Practical Test Standards"). The FAA Commercial Pilot ACS can be found at https://www.faa.gov/training_testing/testing/acs/media/commercial_airplane_acs.pdf. Presumably Transport Canada has some equivalent, it may contain exactly the same language. In any case, you should read whatever document governs your flight test and see if it has anything to say about configuration for slow flight. Yeah, in a 172 the only real choice is where to set the flaps, if any. Way back in the 1990s when I was doing my private pilot training, the instructor that taught me slow flight wanted flaps fully extended (all the way to 40 degrees in some 172 models!), which in turn required enormous amounts of power to maintain level flight. Looking back, I don't think that makes much sense. I demonstrated slow flight in a 172 yesterday to get a CFI checkout at a local flight school, and when I asked the chief pilot where he wanted me to set the flaps for the demonstration, he said he was indifferent about it.

The most experienced instructors I've worked with don't seem to particularly care what configuration is used for slow flight: clean, flaps only, or flaps and gear are all OK. The FAA commercial pilot ACS (do you use this in the Great White North?) doesn't require any particular configuration for the slow flight task, so it really is the pilot's choice... in theory. In practice the examiner may have preferences on the check ride, so it behooves to you to talk to him in advance if possible. That said, the ACS does require the "landing configuration" for power-off stalls and "takeoff configuration" for power-on stalls. Since both of these require gear down, and since slow flight work is often combined with stall work, I typically fly slow flight with the gear down. I also tend to set the flaps to the "takeoff" position, since this reduces the required pitch attitude to maintain level flight at low speed. You can certainly fly slow flight in the clean configuration, but the higher pitch attitude required to do so is less comfortable, and can have a negative impact on cooling.

Airspeed is proportional to power cubed, not squared. A 5% increase in power only gives you about a 1.7% increase in speed, i.e. 153 KTAS becomes 155.6 knots. There may be some good reasons to go with the IO-390, but cruise speed isn't one of them.

I've had really good results from these guys: http://www.engravers.net/

'76 M20F - partially mine, in a partnership '67 TR4-A - belongs to the wife (I married up!)

And a third, namely how it will affect business when/if word of the denial spreads. Aviation insurance is a small industry, not at all like auto, homeowners, and health insurance. I've had multiple brokers tell me claim denials are infrequent at least partly due to industry dynamics. A reputation for weaseling out of claims on technicalities (even when the carrier is legally right) is harder to mitigate in aviation than in the trillion-dollar scale of those other insurance markets.

At least one company (Avemco) used to publish a detailed list of their claim denials every year. It appears they've stopped doing so, but I doubt things have changed much since 2011: https://www.avemco.com/Articles/ART0006-2011.pdf The money quote from that article is, "Of our 460 claims, only 6 (or 1.3%) were denied for all reasons." You can read about the detailed reasons in the article. Most of them are obvious issues almost no one would argue with, such as aircraft being operated by a pilot not named on the policy, or filing an in-flight claim when the policy holder explicitly chose to purchase a no-in-flight-coverage policy. Avemco handles the medical/annual thing by asking if you have one at the time the policy is purchased. Assuming you don't lie about it, they don't deny claims if you later have an incident after your medical/annual expires. Not intending to shill for Avemco here - I used to be a customer but haven't been in years. They're just the only aviation insurance company I know of that has ever published their claim denial statistics. I assume the market is competitive enough that other brokers/underwriters must have similar statistics, but can't say for sure.

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.