Vance Harral

I try not to be an alarmist. But I think you better call LASAR first thing tomorrow, and ask if the gasket you received was from the same batch as the one Dan used to assemble our fuel selector. If it was... or maybe even if it wasn't... I would not fly the airplane without pulling the selector bowl and inspecting the gasket. Go look at the video in my OP again, and think about what happens if your gasket lets go in the air.

OK folks, here are some pictures of the gasket under a magnifying glass. This is definitely not right. The material is pitted, and has an "orange peel" or "chocolate cake" appearance. My airplane partner says it looks and feels like foam rubber. Either the material was crap to start with, or it was attacked by fuel, and/or the fuel lube used to assemble it. When I get the new gasket tomorrow, the first thing I'm going to do with it is simply drop it in a jar of 100LL for a few days and see what it looks like after that.

So I called Dan at LASAR and (politely) asked WTF. His response was that he definitely replaced that gasket when he worked on the selector two weeks ago, but... this is not the first report he's had of this sort of problem, recently. These gaskets are not generic parts. They are Mooney-specific parts that come from the factory. Yeah, I'm sure the factory just cuts them out of a sheet of butyl rubber or whatever, but the only legal source is the factory. So one possibility is the factory has produced a set of crap gaskets that deteriorate in the presence of 100LL. Maybe that caused cferr59's problem? Dan claimed he'd be on the phone to Mooney immediately after hanging up with me. The other possibility is that Dan is fibbing to me, to cover up shoddy work. I can't discount that 100%, but I honestly have no reason to believe it could be true. We've worked with LASAR in general, and Dan in particular, for over a decade with no issues. Dan is overnighting us a new gasket, supposedly from a different lot of parts. He's also still digging around for salvage fuel selectors. Assuming we install the new gasket and everything holds... how many days/weeks/months do I stare at it on the ground before working up the gumption to fly with it?

My airplane partner dropped the selector bowl a few minutes ago and sent the attached pic. How does the saying go... a picture is worth a thousand words? That seal cannot possibly have been brand new just a few days ago. I don't even know what to say at this point. Too early to be pointing fingers at any particular mechanic or vendor, especially since the part has been in multiple hands. But something about this definitely smells.

Thanks John, I'm very interested.

The main body of the Duke's gascolator has three parts: a top section that contains the springs and balls and tracks that establish the detents, a middle section that routes the ports from each of the two tanks down to the bowl, and a bottom section that is the bowl itself. It's possible these are made of anodized aluminum - I'm not a materials expert - but it doesn't look like it. Dan says they are made of cast magnesium and I'm inclined to take his word for it. The bolt in question has a "washer" with embedded rubber. It's called a Stat-o-Seal. That's not where the leak is coming from. As you said, the leak is from the seal between the bowl and the middle portion of the body. The bowl and the middle portion of the body do *not* have a pristine interface. As mentioned above, the salvage selector from Alan had some light pitting. All this was cleaned up with scotch brite. But because we're forced to use the middle body from the salvage selector (that's the part I broke on the original selector), the interface cannot be pristine, there is going to be some pitting there. The opinion of multiple mechanics is that the pitting is not bad enough to prevent a reliable seal. Either that opinion is incorrect, or the seal between these two components is bad/installed improperly. Both the original screen and the screen from Alan are long since in the garbage. I bought a new screen from LASAR for the annual this year (I install a new one every few years). I installed this year's new screen right before I broke the original selector. That screen was included in the parts we sent to LASAR. I don't know if Dan used that screen when he reassembled the selector, or yet another new screen. But whatever the case, we're not dealing with a 50-year-old screen. It's interesting to wonder if this is part of the problem. As we all know, sometimes prophylactically replacing a part introduces new problems that weren't present with the old part. Won't know until I work up the heart to go back out to the hangar and start disassembling the selector for the Nth time in this saga. I'll keep everyone posted.

We installed the selector as received from LASAR, we did not disassemble it on receipt to check the work. We're all human, and it's possible Dan installed the wrong seal or assembled the unit improperly. But that would be unusual for a shop/person with that much experience. I'm still decompressing and waiting on a follow-up call from Dan so I haven't been out to the hangar to remove the bowl and look inside. That's the obvious next step, and I'll report back here on what I find.

Thanks John, please keep me posted. I don't know what the various different selectors look like, I'm only familiar with the Dukes in our aircraft. Perhaps someone else can assist us with photos.

Dan says he'd like to try to make the Duke's selector work, but is presently researching other alternatives so he can give me options. I appreciate Dan's interest in making the old selector viable, and I haven't 100% ruled out giving him another crack at it. But LASAR is in California, we're in Colorado, and the airplane is AOG. So every try-again cycle involves 4 days and about $100 worth of round-trip shipping. I'm not a penny pincher, but I've already put two months and 1 AMU of effort into making the old one work, spanning both LASAR and my local shop, waiting on shipping of seals and parts, etc. It just feels like I'm at the point of throwing good money after bad on the existing selector (I've always felt that good/bad money idiom was backwards, but I digress...) Maybe the answer is to bring Dan out here so he can actually work on the problem in situ. I'm sure he has no interest in flying the airlines right now, maybe a fellow Mooney owner in California needs a visit to Colorado and can just bring Dan along for the ride?

No, I'm not sure it's leaking because of the pitting, that's just a hypothesis. When I get over being demoralized, I'll go back out to the hangar, drop the bowl, and see what the gasket looks like. I agree the failure mode seems very odd. Whatever is causing it, I remain tremendously disconcerted the selector could be completely leak free for days on end, then lose it all at once. If it had been dripping slowly at first and getting worse with each passing day, we would have noticed. The selector was installed 9 days ago, and we made multiple trips to the hangar to check on it, switching back and forth between tanks on each trip. Completely dry. Last check was last Thursday, 6 days after installation, no issues. The seal let go some time between then and this morning.

I appreciate the practical suggestion, I'd certainly try something like this if it was an old car. Unfortunately, I don't think there is any manual from Dukes, or method in AC43-13, that covers this kind of work on a certified aircraft. I live in the real world and I understand that sometimes good mechanics and conscientious owners go out on a limb regarding minor and/or low-risk repairs. But machining the mating surface of a fuel system component doesn't strike me as either of those things.

Thanks for the response, Mike. The "whole thing" has already been to Dan at LASAR once, this is the reinstall after receiving it back from him. No aspersions cast on Dan either. What more could one ask for? He actually disassembled the unit while on the phone with me, and described what he found and how he'd reassemble it. He's very experienced, I'm certain he was careful in the reassembly, and everything seemed fine for several days before it sprung a leak. My working hypothesis is that the pitting on the main body of the salvage selector we got from Alan prevents a good seal at the bowl with proper torque, no matter how fresh the gasket is, or how much fuel lube is applied. Perhaps it's OK for a little while with enough fuel lube, but eventually that gets washed out. One could try overtorquing the bolt that holds the bowl on to get more clamping force, but... that's what got us here in the first place. I could send it to Dmax, but I can't imagine what he would do differently than Dan. What gives me the heebie jeebies is the likelihood someone will get the seal to once again be OK for "a while", then it will suddenly let go again. Possibly in flight. Based on the rate at which fuel is spewing out in the video above, my guess is it took way less than an hour to completely empty a full tank. I don't want to lose another $100 worth of fuel on the ground in the hangar, and I really don't want to be worrying about this in flight.

I'm working with Dan at LASAR on this problem, but figured I'd seek advice here on the forums too. About two months ago, I broke the Dukes fuel selector in our '76 M20F by overtorquing the bolt that holds the bowl on. The story of exactly what happened and why is a cautionary tale for another time, but for now let's just say I take full responsibility, even though I was working "under supervision" by a certified A&P who was only a few steps away. I was able to obtain a salvage fuel selector from our local Grim Reaper, @Alan Fox. Unfortunately the selector was not in pristine condition and had some pitting, particularly at the interface between the lower body and the bowl. No aspersions to cast on Alan here, he sold me the part "as is", and I accepted that as the deal. The local shop installed new seals in the selector, but it leaked fuel at the bowl. The selector was disassembled and a "Frankenstein" selector was assembled using most of our old selector, but the main body from the salvage selector. When installed in the aircraft, the selector leaked fuel through the selector shaft. The shop removed the selector and replaced the seals again, but same problem. We pulled the selector again and sent all the parts - original and salvage - to LASAR. Dan at LASAR found the local shop had been nicking the shaft O-ring on reassembly due to the sharp edge where a flat is cut into the shaft to receive the set screw on the selector lever. He filed a small radius on the cut, reassembled the selector, shipped it back to us, we installed it, and it held fuel with no leaks for several days, with the selector in both the left and right positions. Went out this morning to finally fly the airplane after two months of down time and found the right tank completely empty, and the belly and drip pan covered in blue stains. Pulled the panel beneath the fuel selector, switched to the other tank, and observed the massive, gushing leak at the bowl shown in the attached video. At some point in the last couple of days, the seal at the bowl simply "let go", and poured about $100 worth of avgas on the floor. The failure mode is scary: one of the most qualified people in the industry almost certainly did everything right in IRANing the selector, it looked good for several days on the ground, then it just started gushing fuel. Thank goodness it happened on the ground! Needless to say, we've lost faith in this particular collection of parts. The Duke's selectors aren't made any longer, nor are the H&Es, so Mooney sells a retrofit kit P/N 940073-503 for some other type of selector. When our own @Jim Peace went through this drill in 2016, the cost for the retrofit was $2400. I learned this morning it has since doubled, to just below $5000. Furthermore, it's my understanding from Dan at LASAR that the retrofit kit may require moving the position of the selector, rerouting fuel lines, etc. such that it involves nontrivial labor costs in addition to the parts. The conventional wisdom is, "Don't buy a new selector, just get yours overhauled and it'll be right as rain". But again, we've already been through multiple iterations of this, including work by one of the most respected folks in the business, and I'm at wits end about how to proceed. First choice would be a known good used selector from some M20F just recently condemned due to something awful like spar corrosion, etc.; but of course I wouldn't wish that on another Mooney owner. Next choice is the retrofit kit, I guess. Next choice is yet another salvage unit of unknown provenance. Absolute last choice is trying another round of seals in the existing salvage selector. It's been nothing but trouble, and has exhibited a scary failure mode. We've lost faith in it. Any advice, denizens of MooneySpace? IMG_9513.MOV

You're awesome, Paul! I'm giving a Flight Review at KBJC this Saturday, any chance you'll be around the airport that day?

My caps are not tethered. However, if you place them somewhere other than right next to the hole while fueling, you are more likely to forget to put them back on. Ask me how I know.

That's a kind offer, Paul, and a good excuse to get together. How 'bout you evaluate them and post a PIREP here? I'll buy the spare from you - and lunch - if it goes well. If it doesn't, I'll fund a follow-on experiment and give you one of whatever we try next.

This is an interesting question. The fueling mats for sale at Spruce are made of polyurethane. My understanding is the electrical properties of silicone and polyurethane are similar. I think the silicone baking mats we're discussing here are probably "fine" vs. purpose-designed choices in terms of risk. But now that I think about it... regardless of the material used, I'm thinking you probably want to ground the airplane before laying down the mat, and (perhaps more importantly) remove the mats before you disconnect the ground. That would seem to be the lowest-risk procedure.

Silicone baking mats sound like a great idea. Thinking something like this would fit the bill with a DIY hole cut out: https://www.amazon.com/gasare-Silicone-Countertop-Protection-Resistant/dp/B07K6YZY21

Even an old workhorse with bad paint shines up pretty decent with basic products from the auto parts store. All it cost me was a few bucks and a lifetime supply of ibuprofen for my sore shoulders and forearms. Haven't flown it yet, will hope for good results like GLGA!

Just finished a multi-day job of polishing up the airplane. It'll always be a workhorse rather than a beauty queen, but polish and wax still make a difference. One of the high-elbow-grease parts of the job was polishing all the marks and scratches around the fuel caps from the fuel nozzle, and from laying the caps themselves on the wing. I'm thinking about carrying a fueling mat in the future to reduce this. Ideally something small and lightweight - just big enough to shield the tank opening a few inches on all sides, with enough spare room to set the cap on. Spruce has some fueling mats, but the high-end model is expensive and seems designed for commercial use; and the low-end model gets poor reviews. Both look heavy. I've seen much smaller/thinner mats that look more appropriate for personal use, but after searching for them online to no avail, I'm thinking they were probably DIY jobs. For those of you that use fueling mats, any suggestions?

I understand now that you and I are talking about two different things. You are talking about not losing gross control of the aircraft: getting upside down, ripping the wings off, etc. I agree almost any "low end" backup attitude indicator is helpful in reducing that risk, including the imprecise AHRS in the GTX-345. I also agree the risk of complete loss of control is reduced at slower speeds. But I'm talking about executing an instrument approach to minimums, well enough not to get off course resulting in CFIT, even though the airplane is still flying at normal attitudes. My odds of being able to do that traditional partial panel were "decent" because I practiced it... at least until a recent 2+ month hiatus due to the combination of a complicated annual and the COVID pandemic. But even at my most proficient, there has always been room for improvement in my partial panel skills. Accordingly, I chose not to fly my airplane over widespread low IMC. I was considering changing that strategy after installing a GTX-345, with the rationale that I now have attitude backup if my vacuum AI rolls over and dies. Based on what I've seen actually flying with the iPad and GTX-345 though, I've flipped back to my original mindset. I reserve the right to adjust my risk profile yet again with further practice, but I'm not there today. Having said all that, my original point stands: I've met pilots who changed their risk management profile based on having backup attitude information they have not actually practiced with. That's a sketchy idea even with a high-end, certified attitude backup solution. It's an even worse idea with a portable, uncertified solution. Go practice with your backup, then adjust your risk management profile based on your experience. Make the decision based on real flying, not armchair flying.

Has anyone called Brittain lately? I'm not sure of their "hibernation" status. Right after Jerry died, we called Brittain and ordered a set of the rubber boots to stock in our own personal inventory against future ruptures, though we haven't used any of them in anger yet. It was some of the very last stock of boots, I think. I thereafter read reports of Cecelia telling other callers she had no common parts in stock, and that she was simply trying to keep the company alive until a new investor could be found. One assumes that if a new investor is able to resurrect Brittain as a going concern, manufacturing new boots and getting back into the servo overhaul business would be their first priority. As for "finding some servos only a few years old", I don't think anyone has manufactured completely new Brittain servos in decades. The best you can get is new boots/seals/tape on old cans; but that's OK as the cans are essentially indestructible. There was a time when Brittain would ship an overhaul kit to the field with boots and seals; but in latter years the FAA got on their case and required them to have customers send servos to the factory for overhaul. You can let your conscience be your guide on what that means when the manufacturer is no longer able to provide the service. I consider it to be an "owner produced part".

The problems I described with my experiment using the iPad as an emergency backup occurred while flying level approach at 90 knots. I disagree with the suggestion they can be alleviated by slowing down. Or, if they do vary with speed, I actually think you have it backward: I think they're less of an issue in cruise than they are on an approach. Let me elaborate on a couple of things. First, it's not that I had trouble keeping the aircraft upright or that I was ever anywhere close to an unusual attitude. Rather, the errors and lag in the displayed attitude resulted in my chasing heading/track and altitude excursions. e.g. I'd set a straight and level attitude on the display, but see track and/or altitude slowly changing. So I'd input a small bank and/or pitch correction to fix that - which might or might not be immediately reflected in the attitude display. Then I'd try to re-frame my brain, like "to hold a constant heading, I think the display needs to show a 2-degree left bank"; only to discover the error didn't seem to be consistent. The net result was that my performance wasn't really any better with the backup iPad attitude display than with traditional partial panel technique. I mostly blame this on the GTX-345 AHRS that generates the attitude information. I've seen several reports that it's simply not a high-quality attitude reference, and my own experience agrees: OK for emergency backup, but just not accurate enough for the single-digit bank angles and half-bar pitch changes associated with precision instrument flying. My guess is most of the AHRSs people are thinking of as emergency backups are similar: Stratus 2/3, Sentry, GDL 52, etc. I freely admit I only have experience with the GTX-345. But my technical reading on the matter leads me to believe there's a good reason why certifies AHRS systems are expensive, and inexpensive AHRS systems aren't certified. The second issue for me wasn't a problem with the hardware/software, but rather a lack of experience with high-end, digital attitude depiction. I have essentially no time behind a G1000, Aspen Evolution, etc; and therefore no experience with synthetic vision depictions. By default, the Foreflight attitude display is backed by synthetic vision information: it includes both terrain depictions, and augmented-reality pointers that show nearby airports. What I didn't appreciate until I tried it is that if you hold a fixed pitch/roll attitude on this sort of display, the depiction changes even though your attitude is not changing. Perhaps this is intuitively obvious in a turn. But even when flying straight and level, terrain and airport pointers slowly slide down and to the side of the display as your position moves forward. Not being distracted by this requires an adjustment in thinking, even on a huge display with an infinite pixel count and frame rate. On a small display with limited pixel count and limited refresh rate, it's even more distracting to a pilot used to looking at an old iron gyro, or even a digital presentation with a simple sky/ground background depiction. I have no doubt I can get used to this, and I'll continue working on it. But it's another great example of how a very nice tool can get a pilot in trouble if they're trying to use it for the first time in a high stress situation.

Strongly suggest those of you relying on an iPad for emergency attitude information cover up your traditional instruments and actually spend some time flying with it during training. I'm sure some of you have, but for those that haven't... when I gave it a shot, I found it surprisingly difficult. Partly this is due to the AHARS built in to our GTX-345, which turns out to be marginally OK for keeping the greasy side down, but rather poor for precision control (frequently shows a slight bank when straight and level, and lags actual attitude just enough to make fine control difficult). Partly this is due to the Foreflight display, which I found distracting and "swimmy" for various reasons that are probably just personal. The point here is not to say it can't be done, it most certainly can. But it's just different enough that I sure wouldn't want to be trying it for the first time in an actual failure scenario. My casual poll of a locals who are excited about the emergency backup capability of their iPad suggest about half of them have never actually used it in real or even simulated IMC. Like any other tool, it shouldn't be relied on unless you've trained with it.

The part number I quoted is what was shipped to us for our 1976 M20F with the Duke's selector, by LASAR a couple of months ago. I believe it's the same selector used in your aircraft, but it's possible I'm wrong. To be honest, the screen wasn't an absolutely perfect fit for us - the inner "doughnut hole" was a little on the small side and had to be slightly stretched around the center port of the selector. I don't know what the difference is between the P/N I quoted and the one you found on LASAR's site, or if that has anything to do with the fit. In any case, strongly suggest you just call the LASAR parts department Monday morning and chat with them. This is the kind of thing where you're going to get a lot better answer from a human on the phone than from browsing a web site. Your order wouldn't ship until Monday if you placed it on the web this weekend, so there's no reason not to call. As for the screen itself, I wouldn't say the edges of it are "sharp". But they're just cut out of a mesh screen material, they don't have any kind of refined edge that keeps them from fraying if mis-handled. I do have a hard time believing your screen shredded your gasket through pinching and/or vibration, though. The screen material just isn't that robust, and the assembly shouldn't result in the screen grinding hard on the gasket anyway. It looks more to me like the rubber gasket just got brittle and crumbled over a long period of use without replacement. Just a guess on my part, I'm not an A&P and don't have that much experience working on selectors. I have zero experience with the gaskets from Brown mentioned by MB65E, but it's likely they're fine. Uou're not going to get that Mooney-specific P/N gasket from Mooney themselves anyway, at least not at the moment. My airplane partner has been trying to get a hold of them all week, and they are returning neither phone calls nor e-mail. So the choices are LASAR or other MSC, or Brown.