Vance Harral

A couple of folks above have suggested the brown staining around the fuel tank access panel is sealant "oozing out" from a prior R&R job. Maybe. But it's more likely to be fuel seeping through the access panel from degrading sealant. The blue dye in 100LL fuel turns reddish-brown over time and leaves these sorts of stains. Significant leaks show blue staining, but very small leaks (or leaks that have been recently cleaned of blue staining) show only reddish-brown marks at seams. I know this from observing our own airplane, which has had access panel seeps over the years. For another example, see the first half of the attached video, which shows significant Mooney fuel tank weeping. The reddish-brown stains in the video aren't rust, they're what's left when the blue dye dries and desiccates.

Hrmph, sorry about that. I just assumed this was the same on all airframes that had the Brittain aileron servos, but clearly not. I'll try to remember to take a photo of mine next time I'm out at the hangar.

Glad they helped, good luck with your project! For what it's worth, suggest you pay heed to jetdriven's troubles with binding after reassembly, which is part of the reason we sent our unit to LASAR for overhaul. We spoke directly with Dan Reisland about this, and he said reassembly of the "guts" inside the block (bearings and shims) is critical, and if not done just right can lead to exactly the sort of binding jetdriven talks about. My guess is it mostly has to do with selecting the right size shim(s) to minimize play without binding up. The right size depends on detailed tolerances of the block and the bearings, and installing different bearings affect that, even if the new bearings are the same part number. So something of an art, based on experience. That's my impression, anyway. If you're just going to clean and reassemble your existing parts, I'd guess odds are they will go back together fine. If you're contemplating new bearings, or your shims are worn, or you just want a slightly bigger shim to tighten up play, you may want to let the pros do it. At the risk of sounding like a shill for LASAR, Dan was extremely helpful to us with this, as well as our landing gear work, at our recent annual. I'm sure the LASAR guys would be the first to tell you these are just mechanical parts and they're not some sort of mystical gurus. But they do this sort of thing every day, and experience counts.

The problems that can occur when the system is neglected - which it often is for long periods of time due to the pain of disassembling it - are as follows: Old, dried up grease in the bearings - this wasn't as bad as I thought it might be in our airplane. It is essentially sealed, after all. Wear in the bearings from normal, long-term use - this was our biggest problem. Shims worn, or not the right size in the first place. You can see in the photos above we had only a single shim, and was allowing a fair amount of play. Wear in the "screw" itself. In our case, there was almost no wear, and the folks at LASAR say it isn't unusual for it to actually be in quite good shape when inspected. When we got things disassembled to the point of the last photo above, we realized the bearings were in fairly bad shape. We hadn't yet ordered replacements, and when we realized it would require a puller to get them off the shaft, we chickened out and just overnighted the whole thing to LASAR. Dan fixed us up and had the freshly overhauled unit back in our hands in less than a week.

If you remove the bolts and nuts that hold the "block" together, you can slide it off the bearings that allow the screw to turn, as well as remove the shim(s) that take up the play in the system: Here's the shim: Here are the bearings after sliding the block off. Note that the bearings are press-fit onto the shaft. You need a puller of some sort to remove them: This is as far as we got before we chickened out:

Not PeytonM, but we overhauled our jackscrew assembly (by which I mean we R&R'd it, and had LASAR actually do the overhaul) just about a month ago. Here's what it looks like when first removed from the airplane. The big block in the middle contains the "nut" and the bearings. That's where you're going to find the old, dried up grease, as well as the (probably worn) shims. The shaft on the right attaches to the trim control rods that go down into the belly. The "screw" part on the left attaches to the tail, and is what's underneath this boot you can see when you remove the empennage fairing: Note the hole at the far lower right of the above photo. There are four of these, and that's how you get access to the bolts that go through the square block, and hold the jackscrew assembly in place.

Thanks for the info on traffic alerts, Maurader. Based on your pointer and a little more research, looks like both the GTX-345 and the NGT-9000 call out azimuth, high/low, and distance. The connection to a WAAS GPS isn't an issue for us because we already have a GTN-650. So the flip-side of the argument is that with the NGT-9000, we're arguably paying for a WAAS GPS receiver we don't need. We don't have any installation quotes yet, so time will tell on walk-away price. But I can't imagine the installation costs on our particular airplane would vary much between the two boxes for just their respective basic feature sets. That just leaves the price delta on the hardware itself. The partnership is hoping to get out of the shop for $7500 or less. Maybe way less, as various, much-less-capable options are also still on the table for us. But we wont' really know until we start requesting quotes. The only thing we know for sure is TAS is off the table - we'd rather spend those dollars elsewhere. That makes the comparison between the GTX-345 and the NGT-9000 a close heat.

Thanks Maurader, great explanation. Question for you: when the NGT-9000 generates an audio warning, does the voice tell you where to look? Something like "Traffic, 2 o'clock low!". Or does it just say "Traffic!"? And is it any different with the Garmin products?

I'm still curious where the TargetTrend algorithms are implemented. If they're in the 345 itself, then any display device - including Foreflight, FltPlan Go, etc - could theoretically display those trend vectors. If they're part of the software in the display device instead (GTN-650 or Garmin Pilot or whatever), it's unlikely Garmin will ever give Foreflight or another EFB vendor the algorithm. Also, if they're in the display device, then two different devices could potentially be running two different versions of the algorithms. I can see this coming up with traffic display on a GTN vs. Garmin Pilot. Garmin does a decent job rolling out GTN firmware updates, but it's a little annoying that we have to make a trip to our avionics shop and drop them a check for $100 every time we want the latest GTN firmware. I'm aware some avionics dealers do this for free as a courtesy, but the shop that installed our 650 isn't one of them. Consequently, we only upgrade the firmware every year or two, instead of every time an update is available.

Well, for one thing, you apparently can't buy one any more. That page you linked to says "Sorry, the requested product is not available", and I can't find one for sale anywhere but Ebay. I think the relaxing of TSO rules, combined with the relatively small price difference between portable/backup AHRS units that display on an EFB and things like the Dynon D10 and Garmin G5, have essentially eliminated the market for things like the Dynon D2.

Can someone expand on TargetTrend? Garmin isn't the only vendor which provides a traffic display that paints a track vector for threats, so I'd like to better understand the details. For example, here's a screen grab from an AOPA article on the Lynx NGT-9000. There is clearly a vector line for the yellow threat target, and the two non-threat targets have altitude trend arrows that indicate those aircraft are climbing: My understanding is ADS-B/ADS-R message content includes latitude, longitude, altitude, heading, and horizontal and vertical velocity. While the message itself doesn't contain any "trend" information, it's pretty trivial to compute a future position for a target, assuming it doesn't change its current flight path. It seems like I've seen a lot of traffic displays with this sort of trend data. This gets more complicated if the target is changing it's flight path. I can imagine a "smart" box comparing several data points for a particular target, realizing it's turning, and heuristically painting a curved vector for the target on the display. Does TargetTrend (or similar products from other vendors) do this?

This would certainly be an important piece of information. @Cruiser, can you provide a link to this recommendation, or is it just something you heard in passing?

Right. And at around 1 AMU for the 660 and a panel dock, that's considerably less expensive than a G5 or similar. Still a lot more expensive than velcro'ing an old cellphone to a blank spot on the panel, though, which is what got this thread started. Decisions, decisions...

Well, I'm not sure I'd call the AHRS in the GTX-345 "portable". It's hard-mounted in a unit that's as firmly fixed to the airframe as any certified attitude sensor. If you have an Aera in a panel dock, you can hardwire it to the GTX-345 and get an attitude indicator whose connectivity robustness is equal - or at least very close - to what you'd get with an ESI-500 or G5. The internal sensors and firmware of the AHRS in the GTX-345 may not be as good as an ESI-500 or G5. I don't know about accuracy, update rate, etc., and not sure how I'd research that other than asking for PIREPs. It's also true that if you display the attitude information via Bluetooth link on an EFB instead of via hardwire connection to an Aera (and we don't even have an Aera today), that's a more complex system with more failure modes. But I think the GTX-345 AHRS is an interesting animal in the overall landscape. As a backup source of attitude information, it's robustness is probably somewhere between a genuinely portable solution (e.g. Stratus 2 or iLevil), and an ESI-500, G5, or even a simple Mid-Continent Lifesaver. So not a gold-plated solution, but to me it has nonzero value that makes the NGT-9000 look that much more expensive for its lack of AHRS. And before the cheapskate debate spools up - this isn't about being a certified CB. If our partnership had an extra AMU (or ten, or a hundred) to spend on "safety", there are better ways to spend it than on increasingly robust backup attitude indicators. Primarily training, to be honest. The odds of pilots doing something stupid in VMC due to lack of proficiency are tremendously greater than augering in because their backup AI let them down in the soup. We're not arrogant enough to think we're special in that regard. Again, I appreciate all the thoughts and conversation. Still trying to understand the pros and cons of the many ADS-B solutions available to us. Haven't entirely ruled out a (theoretically) less-expense 978 MHz UAT solution, either. Seems like there's a new solution every few months or so. But we're creeping up on the 2020 deadline, and we want to be equipped by then, even if there's a long wait at the avionics shops.

Thanks for the PIREPs, all. I'm aware the prices for the units themselves are constantly changing. Of course, it's also hard to get an exact cost because it depends on the dealer you work with. When I first looked at this last year, the NGT-9000 seemed considerably more expensive, even without the diversity antenna setup and/or active traffic. Maybe that's less true today. Looking just now, Avionics Source lists the GTX-345 at $4495 and the base model NGT-9000 at $4995. I'm assuming installation costs would be similar in our airplane, so call it a $500 delta if I can get ATAS for free and we decide we don't care about the AHRS. That's not a big difference in the grand scheme of things. The AHRS is a sticking point, though. Yes, it's true its value is only as an emergency backup. But that's a big deal to us - the aircraft only has a single vacuum-powered AI today. This is actually the bigger reason I'm interested in a "panel-mounted" display, even if it's just a phone velcro'd to the panel. For both traffic and back-up attitude, I'd prefer the data be on the panel in my immediate scan, rather than on a tablet that's on the yoke or in my lap. Anyway, if we go with the NGT-9000, we either have to give up on backup attitude, or obtain a standalone solution which increases the total cost significantly. For FIS-B weather, I don't think any of the panel-mounted options are very good compared to a tablet - I'll almost certainly consume ADS-B weather via remote connectivity to the tablet. The display dilemma for me is all about traffic and backup attitude.

Definitely considering the NGT along with the 345, but there are trade-offs. No integrated AHRS in the NGT for backup attitude, so would need a separate solution for that. And audio traffic appears to be a $650 add-on that makes the price delta even larger vs included audio alerts with the 345. So not sure I agree it's "close to the same $". The integrated touch screen in the NGT is nice, and Mooneyspacers that have the NGT seem to like it. But I'm not yet convinced it's a better display option than just having a cellphone on the panel, which you can replace/upgrade/change apps on over time. The real drag with the 345 IMO is Garmin's use of Bluetooth for connectivity, which limits you to 2 connected devices at any one time. When I fly instrument practice with a safety pilot, we both like to have "connected" iPads, and that uses up all the connections. To get a 3rd display, we'd need to use a wired connection to our GTN-650 (already in use for other things of course), or install an Aera in the panel. Our airplane is in a partnership, so the cost of this upgrade will be nicely split by 3. But we don't have unlimited funds, and I'm not yet convinced the price delta for the NGT is a good long-term value. Happy to hear further opinions from others considering the same choice.

When I say "dedicated display", I don't so much mean a dedicated piece of hardware. Yes, that's part of it, but it's the easy part. The hard part seems to be finding a dedicated app - or a simple mode in an integrated EFB app - that shows only traffic, or only attitude or whatever. This, as opposed to split-screening or overlaying the data on top of maps and other junk. In other words, I want this on an iPhone or similar small display "temporarily" mounted to the panel: ... rather than this on a tablet that's on the yoke or in my lap: That seems to make me an outlier, though. Seems like most people prefer the bottom solution. I haven't looked at Garmin Pilot in quite a while. If I understand correctly, you're saying Pilot has exactly what I want - modes that looks like the top picture above for traffic and that would run on a phone, for example; and similar for EFIS display of attitude information. If so, sounds like Pilot has changed since last time I evaluated it, and maybe it's time to take a second look. I'm a fan of Foreflight at the moment. But with a GTN-650 in our panel, contemplating a GTX-345, possibly a Flightstream 510, and the seemingly unending price increases from Foreflight, I could be swayed. Nonetheless, I'm a little surprised Garmin and other vendors don't advertise their hardware works not only with the various big EFB apps, "but also with our free, dedicated display app available on the Apple Store". Doesn't seem like a big investment in software development, but maybe it's just not worth the time and energy vs. integrating with Foreflight/Pilot/WingX/etc.

Boo. As I contemplate our ADS-B in/out options and the various features and gizmos that come along with them, I increasingly find myself wanting a dedicated display for traffic and/or EFIS data from the magic box(es). Velcro a phone to the panel with only traffic, for example - instead of overlaying traffic on top of a moving map, weather data, and all kinds of other combined information on a single Foreflight/WingX/whatever app. But this doesn't seem to be a common model. I'm a little surprised the various hardware vendors don't have more standalone apps for this sort of thing.

My understanding is Foreflight, Garmin Pilot, and now FltPlanGo will all show an EFIS display based on the AHRS output from a GTX-345. I've only personally used it with Foreflight, in a flying club aircraft I don't own. Were you asking about a standalone app that's not an EFB? If so, I agree that would be nice. My research so far hasn't turned up any such apps, but I haven't looked very hard.

I keep reading this sort of thing. But for what it's worth, the Slick mags in our IO-360-A1A have been running fine for 17 years and 1500 hours. They get timed at every annual and opened up for inspection every 500 hours. At one of the 500-hour inspections, our A&P replaced some inexpensive internal parts, that's it. I'm not sure why they have a reputation as "throwaway" mags. Is the conventional wisdom that we're just lucky?

That's a fair question and I don't have an answer for it. I don't hold an A&P certificate. I'm not skilled in the art of trim tube repair or the legal responsibilities of an A&P, and I didn't ask questions about the alloy and heat treatment when the repair was proposed. ... but it remains true that a licensed A&P with a long-time practice and a good reputation made the repair, logged it, and signed it off (most likely based on experience with similar repairs). That makes it legal for me to operate the airplane. Even if this particular repair can be traced to some black-and-white regulation, others can't. I've spoken with enough mechanics to understand at certain points they're simply obligated to make reasonable interpretations of regulations that cannot cover every possible situation - just as pilots must do with the regulations governing operating of aircraft. I'm sure there are "conservative" and "liberal" mechanics in this respect. I respect the spectrum and try to be careful, but I don't lie awake at night worrying about it either.

I agree with your "it depends" assessment. As another example similar to yours, one of the tubes for the elevator trim system in our airplane runs through a nylon grommet, and is subject to wear as described in Service Bulletin M20-185. On the first annual after we bought the airplane, our A&P/IA inspected this tube and found it worn beyond the limits described in the SB. The SB (not an AD) prescribes replacement of the tube, but the mechanic had the tube built up with a weld instead, per techniques described in AC 43.13. He judged this satisfactory because the tube isn't subject to bending or tension or compression loads, only torsion. It was significantly faster and less expensive than replacement. Another Mooney owner I spoke with about this insisted it was an "illegal" repair, but there's simply no basis for that position. Service bulletins aren't mandatory, so replacement of the tube isn't mandatory. The mechanic used approved data from AC 43.13 to make and sign off a repair he believed adequately addressed the problem, which by definition makes the repair legally airworthy. It's fine to debate whether it's a good idea vs. replacing the tube, but it's not "illegal". (For what it's worth, that repair was made 14 years ago and has held up just fine - including a detailed inspection just this year when we overhauled our trim system).

First photo definitely looks like rust on steel components. The others are harder to tell. I've taken various control rods out of our airplane over the years that looked awful in-situ, but that turned out to be nowhere near as bad as I feared. Sometimes, discoloration is just "gunk" - build-ups of dirt, grime, lubrication, etc. Where there is actual corrosion, it's sometimes just "light surface corrosion" that can be cleaned and repainted with minimal trouble once the rod is completely out of the aircraft. Scotch-brite or similar abrasives as others above have suggested. Even if there's pitting, it's not necessarily a deal-breaker. The parts in question can be bead blasted and repainted per techniques in AC43-13 Chapter 6, if they're not "bad". But defining "bad" seems complicated to me, and maybe just boils down to the mechanic's judgement. The oft-cited ten percent wall thickness is a reasonable standard, but note that AC 43-13 and the infamous Mooney SB 208 use this with respect to structural steel tubing, which is not the same as control pushrods. Our own very experienced A&P has been known to look at discolored spots here and there and say things like, "Well, yeah, that might rust all the way through in another 50 years or so. You don't need to do anything about it this year." This used to make me more nervous until I pulled and cleaned and carefully inspected a few such rods. In our case there was nothing of concern, but I don't mean to be cavalier about it - I still think you don't really know until you look closely. In summary, I'm not sure "horrified" is an appropriate reaction by your mechanic. I don't think you were in any particular danger flying this airplane the last year. But it would probably be good to pull the rods out of the airplane and have a close look at them. Odds are they won't require anything other than cleaning, paint, and new AN hardware. Not particularly expensive in the grand scheme of things. Just the thoughts of a pilot and owner who likes to assist with maintenance, though - I'm not an A&P.

Before you disassemble/extract too much to get to the hose running down the left side of the cockpit... you might start by taking out the left (pilot) side carpet panel in the baggage compartment. This is pretty easy and will expose "some" of the tubing, which you can examine for cracks and holes. In particular, you can check if any of the screws holding that carpet panel in place were accidentally screwed into the autopilot tubing. That was the primary source of initial leaking we found when resurrecting our Brittain autopilot. If so, it's possible to patch such holes without replacing all the tubing. If you have a borescope - and from the video above it looks like maybe you do - you can run it down the left side between the skin and the interior panel from the baggage compartment and possibly find other problems, though it might be a tight fit past the roll cage tubing. Good luck with your debug.

Point taken. I guess I don't understand if the "bet" is just for fun, or if he's contemplating ordering parts in advance, or otherwise spending time/money without knowing what's wrong. That's the sort of judgment call mechanics are often pilloried for here, but I suppose it's less of a sin if it's the owner themselves speculating.