Vance Harral

Those look great! Let us know how the prototypes turn out, and... if you'd be willing to share the solidworks data

While Brittain themselves are "in hibernation", I believe they are still answering the phone. Suggest you go to them first with technical questions: http://www.brittainautopilots.com/

Another plug for Alan, he recently helped us out of a jam involving a broken fuel selector. It would not be possible to keep older (and in some cases even newer) Mooneys flying without salvage operators like him.

Veteran of a 16-year Mooney partnership here: 6 different people over those years, 3 or 4 active at any one time. Here's my $0.02 on things that are helpful to have in a written partnership agreement, even among a group of genial partners with lots of genuine goodwill: Operations: Define how decisions about changes to scheduling, fueling, insurance, maintenance, and upgrade polices are made. Negotiate the initial policies however you like, but sooner or later someone is going to propose a change after the partnership is established. Decide in advance whether such changes require unanimous consent or majority vote. For the most part we use the former, but there are certain minor changes that may be made by majority vote. Define how squawks are communicated, so everyone knows what shape the airplane is in. The point of this must not be to assess blame, but only to ensure all pilots are maximally informed about the state of the airplane. The reason the policy has to be written down is so everyone knows where to look for squawk info. It avoids honest mistakes where a good partner tried to communicate something about the airplane, but another partner didn't read the e-mail/look for the squawk sheet/whatever. For what it's worth, I used to think the best way to do this was a written squawk sheet in the aircraft; but it turns out text messages and/or phone calls are better for our small partnership. It allows questions, and helpful back-and-forth about what to do next. Document what level of insurance will be maintained, and - most importantly - if it is always funded equally, or if a less-experienced pilot must carry whatever extra burden they cause on the premiums. My advice? Fund it equally. Actuarial tables don't lie, but that's only aggregated across large numbers. When dealing with individuals, choose a partner you trust, and share the premiums. If you can't muster the goodwill to share the load on the high-experience side and be extra careful on the low-experience side, you don't have the temperament for a a partnership. Decide if anyone ever gets to fly for free in exchange for services rendered. Common reasons for this might include ferrying the airplane to a shop for maintenance, or getting flight time in exchange for performing maintenance or administrative tasks on behalf of the partnership. My advice? Don't even stick your toe in the water on this, always require the rack rate be paid to fly the airplane regardless of services rendered. It's not that I'm unsympathetic to the concept of earned credit, but I think the difficulty of agreeing on specific values for specific services results in flight-time-for-services-rendered causing more problems than it solves. Clearly spell out what happens if a partner is financially in arrears to the partnership. How long do they have to make things right, and what restrictions are placed on their privileges while in arrears? The policy itself doesn't have to be draconian, you can choose to tolerate, e.g., up to $100/month in arrears for up to 12 months before action it taken. But you need to decide in advance when a partner in arrears may no longer fly the airplane, when they are required to sell their share, etc. Equity: Require an annual meeting of the partnership at which you agree and document the value of the airplane, and partners' equity. Having an agreed-on value of the airplane once per year drives a lot of other decisions, e.g. how much insurance to buy, starting point for adding/removing partners, what the widow(er) is owed if one of the partners dies, etc. Spell out a policy regarding changes in equity, particularly with respect to unequal funding of upgrades. Sooner or later, one partner is going to really, really want some upgrade gizmo, enough to offer to pay for all of it, or at least more than their equal share of the cost. Establish a clear rule about whether or not doing so is allowed, and if so whether it changes the equity shares in the partnership. Work up and write up financial arrangements that roughly counteract depreciation over time. The exact details aren't critical, but the value of the airplane plus the cash the partnership has in a partnership-specific bank account shouldn't vary by more than aircraft market fluctuation. This is easiest to explain by a specific, big-ticket example: our partnership bills pilots $12.50/hour toward an engine overhaul. But the reason we do this is *not* to have enough cash in the bank to pay for an overhaul with no out-of-pocket cost. That is an impossible goal, because one never knows when an overhaul will be needed. However, after 16 years of operation and approaching 2100 hours SMOH, we have about $17K in the bank that offsets the fact our airplane is now valued as a run-out, vs. being valued with a relatively low-time engine back at the time of purchase. Financial arrangements of this type minimize arguments over one partner "using up the airplane" by flying it more. They also establish a standard that the financial goal of the partnership is to maintain value. This is really helpful in driving maintenance decisions, e.g. a malfunctioning vacuum AI can be replaced with a G5, but the starting point is to install the same vacuum AI so as to maintain the value of the partnership. Decide what happens if a partner dies. Not fun to think about, of course, but these things can happen, and it's an awful time to try to figure something out. It's best if the partnership agreement spells out something simple, and easy for the grieving spouse to understand and follow. Now, for a change of pace, here are some things everyone talks about which you're probably going to write down, but which I contrarily argue are not really what make or break a partnership: Scheduling policies: Sure, you're going to have some: reserved weeks or priority for scheduling, or maximum trip times, or whatever. But no scheduling rules can prevent conflicting desires, and all that really matters is whether the partners have goodwill about it. Bad partners think, "I've gotta guarantee I get my fair share!" Good partners think, "I'm glad Bob is flying the airplane, the partnership is healthy when everyone wants to fly"; or "Joe has priority on the airplane this week, but I'd really like to fly, I wonder if he might enjoy some company trading legs on his trip." So define any scheduling policy you want, but understand that it's essentially guaranteed partners will ask for variances or changes to the rules (see above). Fueling policies: Sure, you're going to decide on wet vs. dry rates, preferred fuel supplier, preferred storage level, etc. But what you care about is flexibility. When you get home late at night and it's bitterly cold, and you're tired, and the pump/FBO is on the other end of the field, can you put the airplane away with only half tanks and e-mail your partners that you'll make it right tomorrow? Will they write back and say, "No problem, I don't need much gas and I'll fill it up after my flight on Sunday"? If you find cheap fuel on a $100 burger run, can you make an executive decision to fill the tanks for the benefit of the partnership? If the self-serve pump is busted, are you really obligated to pay the FBO rate on the spot to fill to the required level or can you make it right later? These things come up all the time, and you want partners with some graciousness about it. A good test of this is to think about how you feel about paying to replace fuel someone else burned. If you bill a wet rate, this doesn't matter. If you bill a dry rate, are you irritated about getting reimbursed, or do you see it as an opportunity to get together with your partner for breakfast, let him pick up the tab, and call it close enough? Risk management policies: no landings on dirt, no international flights, who is an "authorized" instructor or co-pilot, VFR/IFR/wind limits, etc. You're looking for partners who approximately share your risk tolerance, and who you trust to operate within that general risk tolerance. No written document is going to cover all the corner cases, and even if it did, the nature of risk is such that words written on a page aren't particularly interesting. "Small stuff" of varying kinds: you can write down that everyone should wipe off bugs after flying, require or prohibit the tow bar from being left on the nose gear, require the strobe switch be left on all the time, etc. But real humans genuinely forget or perform to different standards on these things in real life. If finding bugs on the airplane when you come out to fly is genuinely going to drive you nuts, you don't have the temperament for a partnership. Summary advice: fewer rules are better; and it's more important for them to be simple and clearly defined, than it is for the rules to be perfectly equitable in all the various corner cases that might occur. If rule negotiations with a potential partner bring up all kinds of nickel-and-dime corner cases where the person is overly concerned about being treated fairly, that's not the type of person you want as a partner. The guiding principal is that owning in a partnership saves huge amounts of money over sole ownership, and that should make it easy to have lots of goodwill about schedule conflicts and shared costs in the 1 AMU or less range. Hope that's helpful to the OP. I don't claim my way of thinking is better than anyone else's, just wanted to contribute some real-life experience with partnerships.

FYI, for the OP, there is a judgement component to fixing wet wing fuel leaks. One which doesn't seem to get discussed much here in the midst of the black-and-white "fuel leaks are a disaster" vs. "I've never had any trouble" vs. "get bladders" debates. If you read either the Mooney maintenance manual or AC 43-13, you'll find that many wet wing fuel leaks are actually airworthy. Both documents provide guidance on how to determine airworthiness, and the standard is not zero leaks. I quote from the maintenance manual on our airplane: "Slow-to-heavy seeps occurring in open areas, such as wing surfaces exposed to the airstream, are leaks which do not constitute a flight hazard and need not be repaired prior to flight, providing the condition causing the leak cannot result in a leak of greater intensity during flight." So that Mooney you see on the ramp with a blue trickle emanating from a couple of inspection panel screws and/or an outboard lap joint isn't necessarily owned by a cheapskate rule breaker. It might be, but it's about as likely it's been formally judged as both airworthy and safe, by an A&P, and that the owner is continuing to fly it while contemplating long-term options. Not all leaks are airworthy, of course; and any leak of any kind legitimately decreases the value of the airplane. But among people who have never dealt with wet wing airplanes, there is often a perception that the first time a small stain shows up anywhere, it permanently grounds the airplane until a very expensive complete strip and re-seal is accomplished. That's just not the case. Spot patches and watchful waiting are both appropriate ways to deal with fuel tank seeps. In most cases you'll have months/years to notice a leak, decide what to do about it, and still fly the airplane and eventually ferry it to a shop to have the work done as desired. I speak from personal experience here: we bought an airplane with original sealant plus an amateur patch job, in 2004. We knew it would leak soon enough, just based on history. In the 16 years of ownership since, we've had the fuel tanks patched three times. Average cost for the patch work was $1-2K each time. Maybe around $5000 total, or about $300/year, or about $3/hour of flight. So for about half the cost of a full strip and reseal, we've been limping along for twice as long as the warranty a full-strip-and-reseal shop will give you. I'm not saying that's the right answer for everyone, though. If you have a show-quality airplane with a really nice paint job, seeing it seep fuel is painful if for no other reason than cosmetics. Our airplane is a workhorse, which influences our thinking about leaks and patch jobs. To be clear, I'm not suggesting you buy an airplane with a bunch of heavy seeps at face value and consider it no big deal. The problem never gets better on its own, and it will require maintenance in the range of $1-10AMU, depending on how bad the problem is and how you plan to fix it. But to the extent you're concerned about the basic design of wet wings, it might make you feel better to know that they rarely go from leak-free to unairworthy in a short time. By the way, our favorite A&P had a long career with a major US air carrier, and he said many airliners have wet wings and leak a little fuel essentially all the time. The joke was that if you could jump over the puddle it was making on the ramp, it was still airworthy. That's only a slight exaggeration from the actual guidance.

While ours isn't nearly as bad as yours, I've found the AHRS in the GTX 345 to be sloppy vs. certified primary attitude indicators. It frequently indicates several degrees of pitch or bank in straight and level flight, and it's not just an offset or leveling issue - it actively "wanders" over time. I've tried flying under the hood using only the 345 output displayed on Foreflight , and found it more difficult than any other steam or glass AI I've flown with. Frankly, I find it easier to just fly partial panel with needle/ball/airspeed than to use the 345. I've read similar complaints in other forums, and have come to the conclusion the AHRS in the 345 isn't really a serious IFR tool.

Absolutely correct, yes. When I say "DTK is not set directly", that assumes you are in flight plan mode as opposed to OBS mode. These boxes are wonderful, and I think not actually that hard to understand; but they sure can be difficult to accurately describe with the written word.

I'd love to go flying with you in the immediate future, I'll PM you for details.

OK, based on these replies, some time with the iPad trainer app, and a conversation with a buddy, I think I've got this sorted out. I'll lay it out @carusoam style: In GPS mode, the CDI always indicates the difference between the present position and the desired track (DTK). DTK isn't set directly, it's derived from the flight plan. Holds and PTs are just another segment in the flight plan. For hold segments (including HILPT), the GPS sets DTK to the inbound course and keeps it there for the duration of the hold. For traditional 45/180/45 procedure turn segments, the GPS sets DTK to the outbound course on crossing the fix outbound, then autosequences DTK to the inbound course halfway around the PT. The data stream that drives the depicted flight path on the moving map, the "Turn to XXX in YY seconds" messages, and autopilot roll steering data, is independent of the CDI. Some depicted flight path segments are "variable", or what @midlifeflyercalls "optional" above. These are depicted as dashed lines when they are not the active segment. When they become the active segment, they turn magenta, but also change from plain dashes to arrows, to help emphasize turn direction. As I dig into this, one thing that interests me is that the depicted flight path for "variable" flight plan segments change as speed changes. Not hard to understand why, as the turns in these segments are based on standard rate turns, and the radius of a standard rate turn changes with speed. But in a baseline installation, the only speed data the GPS has is ground speed. If the algorithm were really going to be perfect, it would take heading data from a magnetometer and airspeed information from an air data computer, use that to determine winds aloft, and produce flight paths that take into account winds aloft. Do "high end" avionics installations couple this data to the GPS via a input port, such that the GPS can use that information in computing variable flight paths? Further comments welcome, thanks for the replies so far.

Not really a Mooney-specific question, but no luck on another board, and we've got lots of IFR experts here. Note that while the certified navigator in our airplane happens to be a Garmin GTN-650, this is a general question, possibly with different answers depending on different equipment. For various reasons - often "historical" - certain instrument flight procedures are not based on a specific course over the ground. The obvious examples are timed holds and "remain within XX NM" procedure turns. I learned to fly IFR without an IFR-certified GPS, so I'm comfortable flying these segments old-school: by reference to headings and timed legs. I confess I generally ignore the CDI on the outbound leg and through the turns of such holds/PTs, as I'd do navigating purely by ground-based systems. I just verify when intercepting the inbound course that the GPS sequences to the appropriate flight plan segment, and that the CDI guidance looks reasonable. But I'm vaguely aware the navigator paints a magenta line on the moving map for the turns and outbound leg of holds/PT, and that the CDI is indicating "something" while you're flying them. My original understanding was that a CDI in GPS mode would simply depict lateral displacement from the inbound course throughout timed holds/PTs, just as VLOC guidance with a ground-based transmitter would depict angular deviation, and I'm pretty sure I've observed that behavior in at least some cases. But complicating the matter is that holds and HILPTs on GPS approaches are defined by a specific course over the ground, and the navigator could theoretically provide guidance all the way around the hold, much as it does when flying a DME arc in GPS mode. Things get even more interesting in light of stories I hear/read about autopilots with GPS roll steering automatically flying holds and procedure turns. We don't have roll steering, but in an aircraft that does, I think this can only be possible if the GPS is providing guidance throughout the entire hold/procedure turn. So... I'm sitting down with the GTN trainer this morning to fiddle with this, but my initial attempt at understanding was to read the GTN manual, and I'm not actually having any luck there. There are mentions of solid vs. segmented flight plan segments on the moving map in the Flight Plan section of the manual, but it doesn't actually seem to discuss CDI or other guidance behavior. Hoping someone more knowledgeable than me can comment here, ideally with reference to an "official" (manufacturer or FAA) document that describes how this works. Any takers?

Multiple people in the thread are interested, but in my case the aircraft is a 1976 M20F and our alternator is a Hartzell/Prestolite ALY-8520. Regarding the paperwork, we enjoy a good relationship with our A&P, who frequently allows us to perform our own repairs under his supervision and sign them off. I'm not sure that courtesy will apply to disassembling electrical equipment and working on the internal components, however. While there is plenty of debate about what kind of work requires a Repair Station Certificate, the only opinion that matters in our particular case is our mechanic's. If he is unwilling to sign off on letting us do the work ourselves, the cost and hassle of finding someone who will would almost certainly exceed the savings of replacing internal components vs. buying a whole new alternator.

Meaning that replacing these parts requires disassembling the alternator case? I understand it's certainly possible to do so, but it changes the nature of the repair with respect to paperwork.

Anybody have pictures of the diode bridge? We have a similar problem with alternator noise we're going to try to solve at our upcoming annual. Baseline idea was to just buy a new alternator, but I'd be happy to replace/repair a capacitor and/or diode bridge instead, if it's practical. But I can't locate any replaceable components on our alternator, at least not that I can see in-situ with a quick look. I'm only generally aware that "old school" alternators have external electrical components that can be replaced. I understand the principles, but have never actually worked on the guts of an alternator, or seen one worked on. If you talk about this sort of thing in the context of any automobile built in the last 30+ years, you get roll-eyes and an explanation that alternators aren't built that way any more - all you can do is replace the whole unit.

I'm sure @PT20J is correct that the galvanic corrosion concerns are negligible. But for what it's worth, stainless steel is a little further away from Aluminum on the galvanic corrosion chart than mild and chromium steel, and therefore technically more susceptible to the galvanic corrosion problem, not less: https://www.albanycountyfasteners.com/blog/2017/09/15/stainless-steel-and-aluminum/ My understanding is the "stainlessness" of stainless steel refers only to its resistance to iron oxide corrosion from water and/or most air. It's not necessarily better protected than non-stainless steel from adjacent metals or other non-atmospheric elements. That said, I'm not a materials expert and maybe I'm off base here. Happy to be educated by people with a better understanding.

It's obvious from some reading that steel helicoils are inserted into aluminum structures all the time. But isn't this a galvanic corrosion risk?

At the rate those shock disks are inflating every year, I'm not so sure. When we bought our airplane 16 years ago, those things were about $70 apiece. Latest price is about double that, see https://www.skygeek.com/j11968-14.html. So a full replacement of all 11 disks in 2020 dollars is over $1500 just for the parts. Throw in a few hours of labor and the specialty tools you're supposed to use for the job, and you're looking at a $2K expense every 5-10 years depending on your model and climate. I'm a Mooney fan, obviously, but if there were an STC to install oleo struts I'd certainly consider it. The idea of storing your airplane on the jacks strikes me as only about 90% of a joke.

I don't have much experience with helicoils. What holds the helicoil in place? A quick web search suggests it's either the snapped-off edge of the tang (seems very weak), or that you can "glue" it in with thread locker. This might not be an issue with bolts that are installed once in a blue moon, but if you're R&R'ing tie down rings every time you need to jack the airplane, you want the helicoil to stay firmly in place through lots of cycles.

Hmm... after a little research, looks like these are serious chore to remove, and require a special tool to re-install. I can see why they're great fasteners for this sort of application, but obviously not designed for R&R: Nerd video showing super high-tech installation: https://www.youtube.com/watch?v=W62ZJzePjAk Redneck video showing removal: https://www.youtube.com/watch?v=pP4aoLa2eJk

Sure, but the rip-out force should be somewhere around the lift force generated by winds at about stall speed. Any less and the tie-downs aren't really helping the way they're supposed to. Any more and there are some corner cases where you want them to break away because it results in minimal damage. I agree those corner cases do not include gale force winds that flip the airplane upside down. Your point that the corner cases shouldn't include a tie-down mistake either is fair.

That's an interesting point about the nut solution causing spar damage in the event of a mistake. Tie-downs should be robust enough to hold the airplane in place in "moderately high" winds, but not so robust as to bend the spar.

Out of curiosity, has anyone here ever tried to replace this bracket? Looks like it's attached with pull rivets. Can you get to both sides of the spar with drills and rivet pullers to safely R&R in situ, or is this something that's simply not practical without removing the wing skin (which is a non-starter)?

Thanks to everyone for the additional detail, especially @Clarence for the photo and @Shiny moose for expounding on the helicoil solution. As I mentioned, we already have the LASAR tie-down ring/jack point combo, which eliminates the issue with R&R'ing a nut every time we need to jack the aircraft. I'm going to venture out to the airport this weekend, pull the appropriate inspection panel, and verify the tail of the bolt extends up far enough through the bracket for the nut solution. It occurs to me this morning that the nut solution is easily undone if we change our minds about a fix. To be clear, whatever fix we choose will be done at our upcoming annual, under appropriate A&P supervision. Thanks again!

I'm resurrecting this thread to try to better understand the options for a fix, as we've discovered the threads on one of our tie-downs is shot. I'm not having much luck with detail in the parts manual, and it will be a couple of days before I can get out to the hangar and actually look at the airplane. First, can anyone explain what structure the original tie down rings thread into? Is it the spar? A bracket attached to the spar (which could be replaced)? Something else? Second, did the original structure from the factory contain a helicoil? It's unclear to me if the comments from @Hank about installing a helicoil refer to replacing a helicoil that's part of the original design, or drilling/tapping/installing a new helicoil that isn't part of the original structure. My preference would be to fix this problem by keeping the original design and structure, but obviously that's not practical if it involves replacing the spar. If we can replace a bracket and/or helicoil that would be nice. If not, I agree the @Yetti solution seems practical. Note that we actually already have the LASAR combination jack points and tie down rings, maybe the fix is as simple as installing a nut on the back side.

You don't need a high-end articulating arm or mirror attachment to get a good view of intake and exhaust valves. Just buy one of the cheapie cameras, bend the end of the arm around 180 degrees so it's pointing backwards (actually, you want about 175 degrees, to get the best view), and insert the whole thing through the spark plug hole. The hole is plenty large enough to allow this. If you're paranoid you can safety wire the camera end against the cable, but I quit doing that a while back and haven't had any problems. Images are great, see below. There is a slight chance than bending the arm all the way around like this will damage the wiring inside the arm. But that hasn't been the case for me, and even if it did, so what? At $25 for the whole gizmo, it's a low risk.

Before you implicate the boots and go through difficult gyrations to test them, remove the port side interior carpet panel in the baggage compartment and have a look at the PC lines behind them. It will only take a few minutes. The first leak we diagnosed in our PC system when we bought our airplane 16 years ago, was that the prior owner had driven one of the screws for the port side baggage compartment carpet panel directly into one of the PC lines! In our airplane, the offending screw is positioned directly over where the lines run. We repaired the line and left the screw out of the carpet panel on reassembly, as the remaining screws were more than sufficient to hold the panel.