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Everything posted by Vance Harral
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It's important to distinguish between the quantity required for proper lubrication at any given instant, and the ability to maintain that minimum quantity over the course of a long flight. The quantity of oil necessary for proper lubrication (and cooling) is quite small. But the manufacturer of an airplane with long legs must publish recommendations based on completing a flight over the airplane's maximum range, with worst-normal-case oil consumption. I confess I don't fully understand the intersection of engine and airframe certification regulations in this respect. But in practice, the "minimum oil" you need to commence a flight depends on how long you expect to fly (with reserves, of course), and the rate at which your engine consumes oil. Like so many other things in aviation, this can be a complicated analysis, and it's up to the PIC to decide.
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This guy is an embarrassment to Mooney pilots.
Vance Harral replied to Brandt's topic in Mooney Safety & Accident Discussion
I'm a fellow ranter about this. I actually think the industry does instrument pilots a disservice, by evangelizing the idea that you must set up an approach "properly", in advance, so you never have to make last minute changes. Yep, I'm looking squarely at Gary Reeves and the cadre of other CFIIs with their never-program-VTF! screeds, and related advice. These folks set up an idea in the heads of their clients, that GPS approach programming is scary. That you get one shot at it, and you better get it done well in advance of commencing the approach. Any late-breaking change and you're screwed, because it's just not possible to fly the airplane and handle the button-ology. Bunk, I say. Even with the old etch-a-sketch interface on the GNS navigators, it's just not that hard. But like other aviation skills, it requires a lot of practice. Repeated reps of doing the same basic things with a few variations. Unlike other aviation skills, GPS programming can be practiced at home, in short increments, for free. So I just don't think there's any excuse for a modern IFR pilot operating on an instrument flight plan to be weakly or not-at-all proficient in loading a new approach on short notice. -
What is this panel-mounted checklist device?
Vance Harral replied to Vance Harral's topic in Avionics/Panel Discussion
I agree that the panel isn't factory original, so I suppose it's possible the "checklist indicator" is a one-off device. I'm flying the airplane again tomorrow and will - with the indulgence of my commercial student - fiddle with it some more. Speaking of the "STN" switch, we've yet to determine what that switch is connected to (if anything). The current guess is that STN means "station", but we're unsure what "station on" and "station off" might select/indicate. -
WANT TO BUY: Data Loader Cable for King KLN 89B
Vance Harral replied to LANCECASPER's topic in Avionics / Parts Classifieds
Thanks for the pointer, Lance. I confess I was hoping someone had one to "donate", but 0.068 AMUs isn't a bad price for a hobby project. I appreciate your reply. -
This is exactly what happened during my partner's flight. Trivial fix, but the strain relief idea is a good one that we didn't think of. I'll bring this up with our mechanic at the next inspection. Excellent idea, we'll give this a try and report back.
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WANT TO BUY: Data Loader Cable for King KLN 89B
Vance Harral replied to LANCECASPER's topic in Avionics / Parts Classifieds
I'm resurrecting this thread to see if anyone else has a spare programming cable lying around. The flight school where I teach recently acquired a 172 with a KLN-90B, which appears to still work. The airplane is intended for VFR private pilot training, and in an iPad universe it really doesn't matter whether it ever even gets powered up. But I have a soft spot for vintage avionics, and thought it might be a humorous side quest to update it with a database from this decade. I've got a USB/serial adapter, and maybe a line on a recent database file, but I don't have the required DB9 to TRS jack cable. I could probably make one in a pinch, with some research, but it would be more convenient to just buy something. -
On an anecdotal side-note about battery capacity... This weekend, one of my airplane partners had an alternator failure in our airplane - exactly the contingent situation being discussed here. This occurred in IMC, though fortunately he was only a few minutes from home, with a healthy battery and a dual G5 setup that has it's own backups. Anyway... we've done capacity checks on our battery using the "turn on the stuff in the airplane in the hangar" method, and being a bit of an electrical engineering nerd, I even know what the voltage vs. remaining capacity curve looks like for our Concorde RG-35A battery, driving an "emergency" electrical load. The interesting thing is that when the alternator failed - which my partner was alerted to immediately via the bus voltage annunciator - he observed an indicated battery voltage of 11.7V. That's abnormally low for a healthy battery, even taking into account the IR drop between the battery terminals and the voltage gauge. It's much lower than we ever saw on that gauge in our capacity test. Once he got on the ground and shut down, the indicated voltage immediately went back to 12.3. Voltage at the actual battery terminals was slightly higher, of course; but the point is that battery voltage with the engine running was lower than with it stopped. The cause of the failure turned out to be simple: just a broken field wire at the alternator. But his observations suggest that a spinning alternator with a broken field wire actually puts an additional electrical load on the battery, beyond the "turn on all the switches" load one might use in a practical capacity test. I can see how that might be the case, because the alternator output wire to which the battery is connected, would at that point also be connected to an un-energized rotating electro-magnetic system. I confess I haven't dug out my electromechanical machines textbooks to verify that idea, though. Anyone know if this is actually the case? If the hypothesis is correct, then in the event of electrical failure, it might be a good idea to pull the main alternator breaker (not the field breaker) to disconnect that parasitic load. That assumes you can pull the breaker, though. The main alternator breaker in our airplane is of a type that cannot be manually pulled, for whatever reason.
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What is this panel-mounted checklist device?
Vance Harral replied to Vance Harral's topic in Avionics/Panel Discussion
Good guess, but the first time it blinked at me was taxiing from the runup area to the hold short line for initial takeoff. This was after fiddling with it during the runup. The aircraft hadn't been powered up for more than about 10 minutes, so seems unlikely to be a simple timer. -
What is this panel-mounted checklist device?
Vance Harral replied to Vance Harral's topic in Avionics/Panel Discussion
Yeah, you've got the gist of how it works. I think you can choose to interpret the lit state as "done" or "not done" either way, but the manual for the thing probably has a suggestion for one way or the other. What I'm really interested in is what mechanism causes it to blink. Seems like the intent is to signal to you that you haven't completed the checklist; but I'm not sure what's causing it to decide that. -
Not actually a Mooney question, this gizmo is in a recently acquired 172 at the flight school where I teach. But we have a lot of experienced aviators here, thought one of you might have seen one. As shown below, there is a charming, vintage checklist gizmo at the top of the radio stack in this airplane. Pushing the buttons causes them to light up, and pushing a lit button turns the light back off. Moving the switch from "take off" to "landing" seems to invert the state of the buttons: whatever is lit goes dark, and vice versa. That part is straightforward enough, but while checking out in the airplane this weekend, I discovered that the lights sometimes start blinking, for seemingly inexplicable reasons. I think they might be tied to a switch on the throttle. Like, maybe if you move from idle to non-idle or vice-versa, and you don't light up (or extinguish) the lights, it blinks to get your attention that you haven't completed the takeoff or landing checklist? Anyone know the make and model of this thing, maybe have a link to a manual? I think it would be funny to be the one guy at the school who is fully "checked out" (pun intended) on the operation of this thing.
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How to address this hangar rash my plane came with
Vance Harral replied to M20 Ogler's topic in General Mooney Talk
We also bought an airplane with "hangar rash" on the ailerons, though after looking at it for years and years I came to the conclusion it was most likely the result of a ham-fisted attempt to rig them by bending the trailing edges with incorrect tools. Ours was along the inboard trailing edges, not out at the outboard tips like yours. Yours looks, frankly, worse. The skin of that port side aileron appears to be cracked, and would make me nervous. In our case, we flew the airplane that way for a long time. But things came to a head when we needed to replace an aileron control arm bracket due to wear. The bracket is fastened to the aileron leading edge with a conventional bolt and nut, but the nut is inside the aileron, and there is no way to get a wrench on it without partially de-skinning the aileron. We took the airplane to Beegles for that work. The guys at Beegles looked at our ailerons, said they weren't entirely sure they were legally airworthy in the shape they were in (while acknowledging the airplane had been flying for years that way and that it was matter of opinion), and recommended a full re-skin, which we did. We now have much nicer looking ailerons, though the paint doesn't match (in fairness to Beegles, our existing paint is awful, more than the usual challenge to match). The cost was a little spendy, but not earth shattering. I think it was $2-3K, but this was several years ago, so the exact amount we paid isn't really relevant to what you'd pay today. Based on our experience, I'm pretty confident the guys at Beegles would recommend a re-skin of your ailerons. That's not to say someone else might have a different idea, but I can't imagine what it would be. I've seen trailing edges of various surfaces repaired with patches, including - for better or worse - elevators and flaps. But never ailerons in my experience, and never in any case at the corner as is shown in your photos. If you do have the ailerons re-skinned, I'd advise replacing that control arm bracket as well. Again, they do wear after 40+ years, and there is no way to replace them without a partial de-skin. -
A mechanic friend called me today, who I'll keep anonymous because he is a truly good guy and everyone makes mistakes. He was working with an apprentice to swing the gear of an M20J as part of an annual inspection. The apprentice was in the cockpit and working the "lawnmower pull start" mechanism in the J model that manually extends the gear. Well, there wasn't quite enough supervision, and the apprentice kept pulling on the line even after the gear down light illuminated, until it got really hard to move. My guess is the bungee springs on the main rods are bottomed out, and the truss rods are in an excessively over-center position, but I haven't actually seen the airplane. Anyway, my mechanic friend says the gear is now "bound up" and won't move in either direction. In particular, if the system is put back in a normal configuration (tab closed, which is supposed to disengage the emergency spline, then breaker in), selecting gear up with the switch doesn't do anything except trip the breaker for the gear motor. In my M20F, the emergency extension crank can be rotated CCW to move the gear toward the retracted position. Yes, I know the placard in the cockpit says not to turn it that direction, but the M20F service manual actually prescribes doing exactly that during certain rigging operations. So if this was an F model, turning the emergency extension crank CCW might be a way to alleviate the over-extended scenario. But my limited understanding of the "lawnmower pull start" system in the J model is that it's impossible to do this. I can't offer much help to my friend because I'm just not really familiar with the J model emergency extension system, and it's unclear to me what might have actually happened to get the gear bound up like this. Supposedly none of the rods appear to be bent, the system is just under a lot of pressure. It occurs to me that the emergency extension spline may no longer be dis-engaging properly, and that's what's actually causing the breaker to trip rather than pressure on the gear rods. But again, I haven't seen the airplane. Anyone know how to get the gear moving back in the other direction, or at least release the pressure/tension on the mechanism? My friend is contemplating removing some of the bolts that hold the rods in place, but that seems like a bad idea when the system is under pressure, as it might damage parts and/or hurt someone.
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This is one of those interesting cases where newer isn't a slam dunk. GI275s have higher resolution, brighter displays, and features the G5 doesn't. But whether having more, brighter pixels makes up for the physically smaller size of the display depends to some degree on individual eye performance: focus, whether you need cheaters, etc. Some people prefer the physically larger square displays over the higher resolution round ones. So make sure you go actually sit in airplanes with each flavor, before deciding. You can't really tell how it will affect you personally just from pictures. You only have to cut the panel for G5s if you want to flush mount them, and that's not a requirement, though you might have to file the hole slightly out of round to get a pair of them to sit one above the other (we did). But they stick out from the panel quite prodigiously if you don't flush mount - about 3/4". You don't really notice this sitting right in front of them, but it looks ugly from the side. If you're a flight instructor in the right seat, non-flush-mounted G5s also tend to obscure the tip of the steam gauge ASI needle when it's in the most interesting part of the range; and if you install only a G5 ADI and keep your steam gauge DG/HSI, the non-flush mount tends to obscure the top of the DG/HSI, which is of course almost the only thing you care about. Note that the airspeed and altitude tapes on the G5 are not certified primary, and thus are for "situational awareness only", the 275 is superior in this respect. But when I point this out with my flight instructor hat on, response from the pilot in the left seat is nearly always, "Yeah, whatever..." I know most of them are completely ignoring the steam gauge ASI/ALT, and it is what it is. When it comes to battery life, things get really curious. Garmin advertises 4 hours for the G5, but only 1 hour for the 275. 1 hour is "plenty" by a lot of people's standards, but if you're just comparing runtime, the G5 is the clear winner. My guess is that high-end display eats a lot of electrons. Here's a subtle point that's not obvious: the operational knob for the G5 is in the lower right-hand corner of the instrument, while the GI-275 is at lower left. In a "classic" Mooney 6-pack panel, the yoke shaft exits the panel right next to the 4 o'clock position of the lower center hole, which means the knob for a G5 HSI winds up right next to the yoke shaft, and that's an annoyance for us. Whether a lower-left or lower-right knob is better varies from airplane to airplane. Something to think about. Both devices are wonderful instruments and you can't go wrong with either. But as I said, not really a slam dunk to choose the newer GI-275, given the cost difference and the subtleties mentioned above.
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The biggest issue with Cologuard is financial, at least if you use insurance for healthcare. Cologuard has a high false positive rate, about 13%. If your Cologuard test turns up positive, they send you for an actual colonoscopy, which often indicates there is nothing actually wrong. The problem is that at that point, your colonoscopy is no longer a "routine screening" that's covered at 100% by law. Instead, your insurer gets to decide how it's handled, and you typically pay your co-pay or deductible or whatever. That can run into the thousands if you're on a high deductible plan, see https://www.gastroconsa.com/how-cologuard-tests-may-end-up-costing-you-thousands/ I'm sure the people who developed Cologuard and the docs that suggest it mean well. It's a way to screen a percentage of the population too squeamish for the gold standard practice. But because of the way insurance works, it effectively looks like a big financial scam. Just go get the colonoscopy.
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Here's the EGT routing on our IO-360, as of a few years ago. You'll note that the port side routing avoids the ignition wires, while the starboard side routing for the forward cylinder routes alongside the ignition wire and uses the same clamps. Like you, I never noticed any particular problem with data from the cylinder that ran along the ignition wire, and concluded it didn't really matter in practice. That said, the last time I had to replace a probe, I changed the starboard side routing to look like the port side routing and avoid the ignition wire. I don't really like the way the thermocouple wires just sorta hang loose in the breeze, but the wire is monostrand, stiff, and supports itself to some degree. I do think this "hanging in the breeze" arrangement likely contributed to a bunch of problems we had the first few years with the wires fatiguing at the crimps of the blade connectors that joined the pigtail from the probe to the connecting wire that goes to the engine monitor. I complained to E.I. about this and they claimed no one else had the same complaint as me. But then then they changed the type of connector they were using from a spade style to the "OLC" barrel connector, and our problems with wire fatigue have mostly gone away with those connectors. We've replaced several probes over the last ~16 years since engine monitor installation. They do have finite lifetimes. I think the "fast response" (smaller) probes don't last as long as the massives. They theoretically give better response, though. Our probes are further down the exhaust stack than any other installation I've ever seen. We just re-used the holes from an old analog 4-cylinder probe installation. They're further away than the installation manual for our engine monitor recommends, but having been in a bunch of different airplanes with different installations, I've come to the conclusion it just doesn't make any difference where the EGT probes are installed from a day-to-day operational perspective. Since absolute EGTs don't matter, and the numbers vary from airplane to airplane, it's not like you're trying to target any specific range of temps that make location critical. Hard to say what effect probe distance has on longevity - again we had poor luck with this before switching to the barrel style connectors, but that's a problem with the wiring, not the probes themselves. The conventional wisdom is that the closer they are to the cylinder, the higher the indicated temperature, and therefore the shorter the life. But I can't offer even anecdotal evidence that our probes are lasting longer than others' because they're further down.
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Glad to hear from you, Andrew. Thanks for checking in with the community.
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If you need/want the OEM 40:1 Gear Set
Vance Harral replied to Matthew P's topic in Vintage Mooneys (pre-J models)
I think the risk of failure for a gear set that was properly inspected and lubed in the past 200 hours is quite low, and I don't lose any sleep over it. As discussed in other threads, though, the gear set really does wear out over time, even when properly inspected and lubed. That's the reason the lack of availability is so maddening. It's a little bit like being told the manufacturer of your airplane just isn't interested in the availability of brake pads or O-rings or oil filters, or other stuff that you are absolutely guaranteed to have to replace at some point. The long lifetime of the gear set compared to those other consumables makes it a slow-moving problem, but it's a problem nonetheless. -
Your reasoning is logical, but that's not the way humans work. I've given about 1000 hours of instruction. That's not much compared to folks here with a lot more experience, but it's enough for me to have put a large number of pilots with varying experience in situations that make them slightly to largely uncomfortable, in a distracting environment. The idea that pilots will make a rational response to specific problems based on logic like you're stating here, just ain't true. I've seen pilots either lock up, or react "backwards" to all kinds of warning indicators: horns, buzzers, G-loads and so forth. And these are smart people who can tell you all the right answers on the ground over coffee. So I know based on what I've seen with my own eyes, that no one should take any comfort whatsoever from the idea they would "naturally" react properly to an unusual situation. The best you can do is actually induce the situation, and train for the recovery, until it hopefully becomes instinctual to do the right thing. Not instinctual because it's "logical", but just because it's what you did the last N times you actually experienced that situation, in training. Deliberately putting yourself in such situations with an instructor is reasonable for a certain class of problem: stalls, spiral divergence, etc. That's what Scott is doing in the video. There's another class of problem where it's not reasonable to deliberately put yourself in the situation in anything other than a simulator, e.g. engine failure immediately after takeoff. I try to get in the simulator to practice those sorts of things, but I don't do it as often as I should, and I don't suffer from any illusion that I'd be ice cool and always do the right thing in a pressure situation I've rarely or never experienced. I try my best to convince other pilots the same.
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@gsxrpilot is alive and well, I had lunch with him this weekend. But like many folks (not yet including me for better or worse), he has decided that the less time he spends on social media, forums, etc. the better. Even if he was here, though, I doubt he'd have much to say about the 262. His airplane left the factory as a 252 which he updated to an Encore. As far as I know, he doesn't have any more insight into the 231 -> 262 conversion than I do, which is just we both know someone that had one. https://mooneyspace.com/topic/2181-comparison-of-mooney-252-and-mooney-262-conversion/ has a pretty good summary of the feature differences between the 262 and a "real" 252. But it's been so long since either was made, that most of the differences at this point are more about the individual airplane under consideration than the designed features. I think the increasing difficulty in obtaining "conventional" Mooney parts (landing gear parts, intake boots, etc.) is a much larger concern than anything associated with unique aspects of the various Mooney conversions like the 262, Rocket, etc.
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The classic approach prescribes lacing for electrical wiring and Adel clamps for hoses and cables. That said, every mechanic I've ever spoken with about this says they use zip ties where reasonable. "Reasonable" is up to their judgement, like so many other things.
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Splices are acceptable, but soldering them is contrary to the guidance in AC 43-13. The theory is that solder joints are brittle and likely to break, crimp splices less so. I'm not saying I necessarily subscribe to the theory, because I've had plenty of trouble with crimps. But that's the conventional wisdom, and the reason @PT20J - who I greatly respect for his practical experience - is directing you to use aircraft-grade butt splices. More importantly, you should generally be following the guidance in AC 43-13 as opposed to asking Some Guy On The Internet. 11-97 recommends replacing wire that has splices at less than 10-foot intervals unless for a specific reason, so yes it recommends replacing the whole wire even though it's a PIA and lots of mechanics ignore the advice in practice. The whole of Section 13 discusses splicing itself, where acceptable. It says there shouldn't be more than one splice in any single wire segment except in special circumstances. Section 13 also has guidance on acceptable lugs, including the tiny ring terminal on the CHT probe, which really is designed in accordance with industry guidance. FYI, other sections of AC 43-13 provide specific guidance to use "solderless" connectors, and discuss crimping extensively. The only places in AC 43-13 that mention soldering technique are in the context of pins that are mechanically supported in connector assemblies, and - interestingly - the use of solder in mechanical work rather than electrical.
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The OEM CHT probe is a thermistor, not a thermocouple like modern engine monitors use. The good news about this is a thermistor just needs conventional aircraft-grade Tefzel wire, not mono-strand thermocouple wire. You can use the same type of wire for both the CHT probe and your landing light, though perhaps not the same gauge. Something like this should be fine: https://www.steinair.com/product/18-ga-white-mil-spec-wire/ Regarding gauge, the critical factor is to ensure the current carrying capacity of the wire is greater than the circuit breaker which protects it. The whole point of the circuit breaker is to ensure the wiring in the circuit doesn't overheat and catch fire. Here's a current capacity chart for Tefzel wire: https://www.prowireusa.com/tefzel-amperage-chart
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I heartily endorse Aerodon's GMU11 mount! Worked perfectly to mount our GMU11 in the wing.
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Stupid question from a vintage Mooney owner: why do the newer Mooneys have such deep "filler necks" in the first place, given all the grief they cause with actually filling the tank to capacity? I'm not near my airplane at the moment, but my recollection is that the structure that holds the fuel cap on my M20F is only trivially thicker than the wing skin itself. You don't read threads here on Mooneyspace about C/E/F/J owners trying to "burp" their tanks to get more fuel in, as so often comes up with the K/M/R/S/TN.
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Obligatory pedantry from a high-density-altitude resident: manifold pressure at a specific throttle position changes with density altitude. So if you adjust the switch to trigger at, say, about 12" MP around your sea-level airport, it won't trigger above about 8" MP when approaching an airport that's 4000' higher than your home field. That means it might never trigger on a normal approach to that 4000' field. So... if you operate out of both high DA and low DA airports, your options are to have the switch trigger at annoyingly high MP, down low; or potentially not trigger when you need it, up high. We choose the former because of where our airplane is based, others might understandably choose the latter.