Vance Harral

Thanks for the clarification. Yes, the C307PS is what you want. It is specifically called out by name in the G5 installation manual. The D307PS has an integrated A/D converter somewhat like the GAD13. But it converts the current produced by the AD590 to 1-wire digital protocol, rather than the CANBUS protocol needed by the G5. Other Davtron products can receive this 1-wire protocol, e.g. their M303 display. I don't know if any avionics manufacturer other than Davtron supports 1-wire. It's interesting that the D307PS is less expensive than the C307PS, given that by definition it must contain more "stuff" inside. Maybe the D307PS uses an IC which integrates the A/D converter, and is manufactured in greater bulk such that the component is cheaper despite being more sophisticated. Or it might just be a certification or "what the market will bear" thing. Might also be a loss leader to try to get you buy the M303 or other Davtron products.

I'm not sure exactly what you're asking here. Both the Garmin GTP59 and the Davtron C307PS are analog temperature sensors, albeit different technologies. In fact, all temperature sensors are analog devices. The whole point of the GAD13 is to convert that analog information from the probe, to digital information transmitted over CANBUS to the G5. Since I'm feeling nerdy this morning... An OAT probe is just a metal shell wrapped around an integrated circuit. In the case of the Davtron C307PS and similar products, the IC is an Analog Devices AD590. When supplied with a voltage differential across its two pins, this device produces a current that is proportional to absolute (Kelvin) temperature. Data sheet is available at https://www.analog.com/media/en/technical-documentation/data-sheets/AD590.pdf. The data sheet shows that the AD590 comes in two flavors, with two different accuracy specs. Garmin techs like to point out that the "cheap" flavor has a potential accuracy error of +/- 5C (with no external temperature compensation circuit). They imply their competitors use this cheap configuration, while Garmin uses more accurate hardware. These claims are probably true, but I argue they're not meaningful - more on that shortly. In the case of the GTP59, Garmin doesn't publish what IC is inside their probe, but based on the way the GAD13 connects to it, it's almost certainly a 3-wire resistive sensor. These sensors present a resistance which varies with temperature, across 2 of their leads. The 3rd lead is just a short to one of the two other leads. It exists so the controller can measure the resistance of the connecting wires themselves, and effectively subtract that resistance out of the calculation. I'm sure there are high quality/accuracy versions of these sensors. But if I were building an experimental, I might try a ten-dollar, hot tub probe, e.g. https://www.amazon.com/Waterproof-RTD-PT100-Temperature-Sensor/dp/B07DP3LYPX/. At that price, I could buy several units, use the one that tests with the best accuracy in an ice bath, and throw away the others. Garmin probably doesn't buy hot-tub quality sensors, but they almost certainly qualify incoming units from their suppliers, and reject those outside Garmin's own tolerance limits. Anyone else can do this too, though. Again, more on that shortly. So let's examine the worst case scenario on "cheaping out" with the Davtron probe: if Davtron purchases the cheapest version of the AD590, and you are unlucky enough that the particular unit you get has the worst possible error, and neither you nor Davtron performs any QC testing on the probe, you could get a C307PS that is off by +/- 5C. At piston airplane speeds and altitudes (including turbocharged airplanes up to the flight levels), a 5C inaccuracy results in a true airspeed error of 1-2 knots, which is not meaningful. Accuracy is more of a concern if you're talking about whether you'll get airframe icing. But since it's foolish to assume you're completely safe at +1C and completely in peril at 0C with any temperature probe installation, it's hard to argue this has much operational meaning. In practice, we start looking outside for airframe icing any time OAT dips within a few degrees of 0C. So even a 5C inaccuracy is relatively meaningless, other than bragging rights. In reality, though, I think it's extremely unlikely you'll get a Davtron probe that's off by 5C. I presume here that Davtron doesn't have a completely stupid manufacturing process. If my assumption is correct, they assemble the units, then perform some sort of "smoke test" to guard against assembly errors, as well as bad parts received from their IC supplier, just like Garmin. Such a test would catch, and allow Davtron to reject, the very small number of parts at the worst of the accuracy range. You'll have to decide for yourself what you think about Davtron QC. But if you're a cynic about that - and have some patience - you can be your own QC. Buy the cheap Davtron probe, hook it up on a bench, drop the probe in an ice bath, and return it for another if the temperature it reports is off by more than your personal tolerance. Lather/rinse/repeat until you get what you want, and proudly proclaim your CB status. In summary, temperature probes are just a wrapper around an IC supplied from an outside source. Those ICs have accuracy specs on paper, but in reality the accuracy of the probe you get depends on the QC process used by the manufacturer, which potentially rejects outlying units. Garmin's process might be better than Davtron, and it makes sense to pay their price if you're manufacturing a $40M bizjet. For the rest of us, a less expensive solution makes sense; and to Garmin's credit, they support this by supplying an AD590-compatible input to the GAD13. I think that's an entirely reasonable position for Garmin to take, and I happily supported them in buying their GAD13. But I also supported Davtron by using their "cheap" probe.

Another +1 on the Davtron C307PS probe. Many, many G5 installations in the field are using this less expensive probe rather than the GTP59. Garmin will tell you the GTP59 is TSO'd, used in certified installations up to business jets, and achieves better accuracy than the C307PS. All that is probably true, but it's not meaningful in a GA piston single, and not worth the extra cost.

Yep, I missed that one. ... and that one too. I don't know much about it either, but as with "minor modifications" and "standard parts", I expect it will boil down to the interpretation of individual mechanics. I deliberately prefixed my list of methods for approval with "at least" because I was sure I'd miss some. The point is simply that there are many different avenues of approval, so the question asked in the OP isn't really meaningful. It's like asking what regulation prohibits a person from getting a pilot certificate in a certain scenario. There aren't any such regulations. There only regulations that define a variety of methods for various people to obtain various pilot certificates, and you can get one via any of them: traditional experience/check ride, military equivalency, foreign certificate equivalent, etc.

This is, IMO, the most difficult thing to understand about parts on certified airplanes. Everything installed on a certified airplane must have a "basis for approval". But there are many, many such approval mechanisms, including at least: part listed on original type certificate replacement part provided by a manufacturer with PMA aftermarket modification with STC aftermarket component which meets a TSO aftermarket component meets NORSEE standards replacement or add-on is an "industry standard part", see https://www.faa.gov/sites/faa.gov/files/aircraft/safety/programs/sups/standard_parts.pdf replacement or add-on is judged in the opinion of an appropriately certified mechanic to be a "minor modification" aircraft is a "vintage" aircraft and part falls under new VARMA regulations Anyone who tells you that you can't install a non-original part on a certified aircraft without an STC is ill-informed. But that doesn't mean you can install anything you want regardless of STC. If there is no STC which permits installation of the component on your certified aircraft, then there must be some other basis for approval: TSO, NORSEE, signoff as "minor modification", etc. The "minor modification" sign-off is the one that generates the most argument. Appendix A of 43.13 explicitly lists items that count as major repairs/alterations, such that a mechanic cannot really claim those specific items are "minor modifications". Beyond that, though, the definition of what constitutes a minor modification is - best as I can tell - just up to the judgement of the individual mechanic. Some mechanics are a lot more liberal than others with this interpretation.

I know it's a typo and I should just let it go, but... that may be as effective as any other inspection method!

This may be meaningful to the FAA in terms of certificate enforcement. But it means absolutely nothing in civil liability court, and my guess is it therefore means nothing to insurance companies either.

My understanding (I am not an engine mechanic) is that the presence of a small amount of pooled oil on the cylinder walls above the piston during a borescope inspection, doesn't necessarily indicate anything about the rings. Lycomings lubricate their rocker arms and valve stems by spray action through the pushrods. So any time the engine shuts down, there's going to be a bunch of oil in that area. As the engine cools, most of this drains down the hole in the head assembly that connects to the infamous drainback tubes (that themselves are sometimes sources of oil leaks). However, if either the intake or exhaust valve of a cylinder happens to stop in the open position - which I think is always the case in at least one cylinder - some of that oil can wick along the valve and dribble into the cylinder instead of going down the drainback tube. That seems to me to be the most likely explanation for what you're seeing. If your rings are bad, and the crankcase is getting pressurized, it can blow oil up into the combustion chamber. But that oil is going to almost instantly get burned during the next combustion event. I don't think that scenario results in carmel-colored oil on the cylinder walls as seems to be shown in your photos. I'd expect to see carbonized residue instead. Again, I'm not an engine mechanic, and defer to others more knowledgeable. But my initial take is that this is not something to worry about.

I've never been asked for proof of insurance on any of my 5 check rides, but that's just one data point. I suppose DPEs would like to be reimbursed for medical (or funeral) expenses if the applicant crashes during a check ride, though there would certainly be a court fight about the DPE's own responsibility if substantial assets are at stake. But that's not the full extent of the concern. If a check ride results in damage to persons or property not directly involved in the check ride, and someone asserts the DPE has liability, the aircraft owner's insurance isn't going to cover the DPE. The DPE needs their own insurance for that. There's also no clause I'm aware of in the insurance policy for my airplane which waives the right of the aircraft owner's insurer to subrogate against a DPE. Again, the DPE would need their own insurance to cover that situation, though perhaps this is so rare that it's just "customary" for an insurer not to subrogate in this case. I just assumed all DPEs carry some amount of personal insurance for these sorts of concerns, and therefore don't care (much) about whether the owner of the aircraft is insured. But I've never asked an examiner about it. Happy to hear info from someone more informed.

Avemco will update your status, adjust your rates, and send you a pro-rated refund when you get your instrument rating. Or, at least they were willing to do that a couple of years ago when we added a partner to our partnership without an instrument rating, who finished up that rating shortly after joining the partnership. Assuming that's still true (call them and confirm), you can take the $3600 rate in the short term. You're not locking yourself into the full $3600 for the entire year, you would presumably get a rebate from them on completion of your IR.

I speak from direct experience when I say the cigarette lighter plug may have significant IR drop. There are two reasons for this. The lesser is that some of the "cheap" USB chargers that display voltage actually draw non-trivial current. The greater reason is that the wiring at the cigarette lighter, and the mechanism that connects it to the back of the port, was never designed for continuous use; and on older airplanes it has often been neglected and is in poor shape, and therefore resistive. I have personally observed the measured voltage at that port be about 250mV lower than the voltage measured at the battery terminals. I have no doubt many airplanes are in good shape and do not exhibit this behavior. But it's worth noting. You correctly state that the voltage at the battery terminals is the one that matters with respect to charging and battery health. What I'm trying to convey - hopefully in a helpful manner - is that there is not a single value of "bus voltage" everywhere in the airplane. Even with a theoretically perfect measurement device (infinite impedence), the voltage one will find at various points in the system (battery, regulator output, cigarette lighter, input to radios and instruments) varies by at least a few millivolts, and in some cases a few hundred millivolts. This is understandably confusing to people whose V=IR educational punishment was light and/or long ago.

If you're really trying to understand/fix bus voltage in the range of tenths of a volt, then one critical factor is how (where) you measure the bus voltage. Ideally you'd connect the measurement device to the sense terminal of the voltage regulator to start, then sample a few other points: circuit breaker busses, power input of instruments, etc. It's common to have a few tenths or hundreds of millivolts IR drop between the regulator and other locations. Note that cigarette lighter plug-ins and other cheap, portable voltage measurement devices are especially susceptible to IR drop. You don't want to crank up your regulator based on measuring a voltage that's electrically "far" from the output of the regulator itself.

Those stops on our 1976 M20F are a little bent, too. Bothered me the first time I saw it, but I've seen a few other samples since, and it seems this bent look is normal.

There are plenty of M20Js in the Denver area. But if you get no better offers and don't mind traveling a bit north, I can offer you a ride in a 1976 M20F out of KLMO. I'm a CFI, and you can sit left seat if you like. 1976 was the last year for the F model. The instrument panel and interior are the same as a 1977 M20J (including the infamous, superior throttle quadrant ). It's the same body length, and feels/flies essentially the same. It's just about 10 knots slower in cruise, as it lacks the sloped windshield, improved cowl, and various fairings of the J model. You'll enjoy those changes if you're flying a J, but curse them if you're working on one. PM me if interested, but no hard feelings if you get a better and/or closer offer.

Me too. This is an interesting point that I had not considered, thanks.

Politely contrary opinion: keep the vacuum step if it's working. The useful load you gain by removing the vacuum pump, manifold, and servo boot is a few pounds at best, and leaving it installed doesn't hurt anything. Your vacuum pump will eventually fail, but likely not for a long time, and you no longer have to worry about when/if it fails: it's not a critical piece of equipment, won't take anything else with it, and you can easily procure a cheap used/overhauled pump when needed - perhaps even for free, from someone who is removing theirs. Cost of the electric step upgrade is $435 for the kit, plus shipping, plus a couple of hours' labor minimum for the installation work. Weight delta is less than variation in the clothes you wear in summer vs. winter, and the only other benefit is just being able to say you ditched the vacuum system, which I guess sounds cool. I do think the design is nice, and it's a good option for an actual malfunctioning system, but that's apparently not the case for the OP. To be clear, I'm all for replacing vacuum gyros with solid state, that's a separate subject. But I don't get the recommendations to spend money to remove remaining tidbits of a vacuum system that powers working steps, wing levelers, etc. I think that money is better spent on actual flying, but happy to listen to counter-arguments.

Only waypoints along the final approach course are retained. Any waypoints not aligned with the final approach course are removed.

Depends on your other equipment. A Garmin G5 can output "air data", including the pressure altitude a transponder needs to transmit Mode C altitude. However, it can only do so on its CANBUS output, and no transponder I'm aware of has a CANBUS input. If your G5 installation includes a GAD29 - which it probably will to allow your Avidyne 440 to display navigation CDI needles on the G5s - then the GAD29 can also be employed to convert CANBUS data to ARINC-429 data. Many transponders have one or more ARINC-429 inputs, and can be configured to receive pressure altitude over ARINC-429. But your installer must make that connection, and since it's not typical, many don't. In summary, (1) determine if your transponder can receive pressure altitude information via ARINC-429 inputs; (2) make sure your dual G5 installation includes a GAD29; and (3) tell your installer to wire one of the GAD29 ARINC-429 outputs to an ARINC-429 input of your transponder. If all that is done, then yes, you can get rid of your existing altitude encoder.

This change was made in GTN software revision 6.11, released in 2016. But it is incorrect to say the GTN "no longer removes the IAF/IF waypoints" after this change. Activating VTF does still remove waypoints, sometimes including the IAF. It just doesn't remove any waypoints that are along the final approach course. So for example in the GPS 29 approach to KLMO below, if you load the approach from the FIPPS IAF, then later activate VTF, FIPPS will be removed from the flight plan, but FIMUR and MELVN and RW29 will remain. Prior to revision 6.11, only MELVN (the FAF) and RW29 (the MAP) would remain.

Don't apologize. I have a master's degree in electrical engineering and about 30 years' experience in the electronics industry, and I went through exactly the same process. Building avionics wiring harnesses is not especially delicate or complicated, but like anything else you've never done before, there is a learning curve the first time. The difference between you and others is that you're actually trying to read the installation manual and follow exactly what it says. Once you've done your own, start looking at field installations done in other airplanes, and you'll soon discover that many of them are done poorly/incorrectly, and yet still "work".

Try this link, for switch caps in black: https://www.mouser.com/ProductDetail/Electroswitch/SW53AA2?qs=5muX3C0yOnj5E%2FJxlK6wTg%3D%3D&countryCode=US&currencyCode=USD I didn't glue mine on as others have mentioned. I'm sure it will fall off eventually, but it's been there for months with no trouble. At about a buck apiece, just buy a dozen and keep spares handy.

PT20J has it right above: read the AFMS. That said, one key to the Garmin Autopilots is the "scoreboard" displayed at the top of the G5/G3X/whatever. Left side is lateral mode, right side is vertical mode. Green means active. White means armed (one mode can be active while another is armed). Blinking means transitioning from armed to active. I'm deliberately not providing more details, you can get those from the AFMS. But in my instructing, most people I fly with who are surprised by autopilot actions are not correlating the control inputs they're surprised by with the mode in which the autopilot is operating.

It's the connection from the "shield" wire inside a shielded, twisted pair, to the "block" (usually the connector frame) of the device the shielded wire connects to. See the linked video below:

I highly recommend SteinAir for supplies: http://steinair.com. They have videos that show how this stuff wires together: https://www.steinair.com/support/videos/ Among other supplies, they have a reasonably priced pin crimping tool: https://www.steinair.com/product/4-way-indent-crimper/. Others may pooh-pooh this particular crimper as "cheap", but it got the job done for us with no trouble and our installation has been reliable so far. My recollection is that the GAD13 requires only the low-density pins, but for an extra couple of sawbucks you can get the high density insert as well. They also have a nice, inexpensive ratcheting lug crimper: you'll want both of https://www.steinair.com/product/ratcheting-crimper-frame-only/ and https://www.steinair.com/product/insulated-terminal-die-only/ if you need this. Don't use a non-ratcheting hand crimper for this job! Regarding wiring, the 22AWG M22759 unshielded for this job is just for power/ground, so you probably don't need much. But it's inexpensive, so you can get a dozen feet or so of each and have plenty to spare. I like red for power, black for ground, and white for signal, but there is not really an "aviation wiring color code" to follow, and many installers just use white for everything. The M27500 is "inexpensive" shielded twisted pair, and is only needed if you need more than a 10' run from the OAT probe to the GAD 13, because the OAT probe already comes with 10' of shielded twisted pair wiring. The CANBUS wire is expensive, but you hopefully only need a short section to run from the GAD13 to the nearest adjacent G5 or GAD device. Frankly, you can get away with using M27500 for that run, but most people pony up for the CANBUS wire. Also, while I am not discouraging you from following the Garmin wiring diagram to the exact letter, most modern installations I'm familiar with do not run independent shield termination with 16AWG and/or braid as indicated in the wiring diagram. Instead, they use pre-fabricated solder sleeves with pigtail connections, see https://www.steinair.com/product/14-solder-sleeve-wpigtai/. Suggest buying a handful of these in both the 1/4" and 1/8" sizes. You do, in fact, need small gauge solder sleeves *or* crimps to make the "daisy chain" connection for the CANBUS wiring from the nearest G5/GAD device to the GAD13. Buy extra and be careful, as amateurs (like myself) tend to screw it up the first time. Same thing with the ring terminals: they are inexpensive, so buy extra. Highly recommend you purchase a "de-pinning" tool, in case you make a mistake pinning the connectors. Again, these come in both low- and high-density sizes: https://www.steinair.com/product/insertionremoval-tool-for-larger-type-pins-mil-spec/ and https://www.steinair.com/product/insertionremoval-tool-for-high-density-d-sub-pins-mil-spec/, respectively. I think you only need low density. I know I've put a lot of SteinAir links above, but I'm not trying to shill for them, necessarily. I am testifying that we used their parts and supplies for our own DIY installation and found everything to be of good quality.

You are looking for something that doesn't exist. There is no FAR or other government regulation that constrains the ability of U.S. Citizens to receive and log dual flight instruction. Looking for an FAR that expressly permits children to do this is like looking for an FAR that expressly permits women, Christians, Democrats, people who live in Tennesee, etc. to receive and log flight instruction. There are restrictions on non-US citizens seeking flight training in direct pursuit of a certificate or rating. There is also the Child Pilot Safety Act which prevents children from manipulating the controls of an aircraft in pursuit of an aviation record. I presume neither of these things apply to the OP, though only they know for sure.