Jump to content

Vance Harral

Supporter
 View Profile  See their activity

  • Posts

    1,403

  • Joined

  • Last visited

  • Days Won

    2

 Content Type 

Everything posted by Vance Harral

  1. Vance Harral
    Nah, you need to read the rest of the thread. The bolt is the one spec'd in the parts manual, and matches the measurement tolerances for said bolt. The whole design is an "as required" arrangement that varies from hand-build airplane to hand-built airplane. A longer bolt obviously wouldn't work, and a shorter one wouldn't have the required shoulder length. There's a reason the shims behind the baby shoe bracket are spec'd "as required" rather than a specific size.
  2. Vance Harral
    Coming back together. As usual, more blood, sweat and tears (and cursing) trying to get all the bolts and nuts back on vs. getting them off. Particularly frustrating today trying to reinstall the bolts and nuts for the rod ends inside the belly. There just isn't any room in there to work with. I must've dropped and fished out nuts and bolts a dozen times over the course of several hours... It's also essentially impossible to get everything reinstalled without scuffing up the new paint a bit, but it still looks 10x better than before.
  3. Vance Harral
    No, see my post above about which side the head goes on.
  4. Vance Harral
    Great find! I looked on Amazon twice, but must not have found the magic search phrase.
  5. Vance Harral
    I'd already obtained a Lock N Lube based on previous comments here on MooneySpace. So far it's fantastic, truly a great gizmo. I haven't hit every zerk in the airframe just yet and I'm wondering if there will be places where there's not enough space to get the tip locked. But I'm willing to try hard, because once it's locked on, it's flawless.
  6. Vance Harral
    Great idea, but looking more closely, the shipping charges at partdeal.com kill any bargain element. Same at huyett.com. Think I'll look around locally a bit first.
  7. Vance Harral
    The price at partdeal.com is definitely great. But I'd have to order 28 of the little suckers to reach the $10 minimum order. Anyone up for a group buy? Surely there's other cool stuff at partdeal.com I "need". Anyone have suggestions?
  8. Vance Harral
    On a somewhat different note... I'd mentioned the missing grease fittings on our forward trunion bearings earlier in this thread. Turns out the bearings in our airplane are indeed tapped for a threaded grease fitting, not a pound-in barbed fitting. The parts manual specs an Alemite 3018, which is a 6-40 threaded fitting, and I'm able to thread a common 6-32 screw into the hole (close enough when the hole is only a couple of threads deep). On one side the grease fitting was simply missing. On the other, it had been broken off, but I was able to extract the broken shank with a left-hand-cut screw extractor. I now have two empty 6-40 holes awaiting a solution. I packed grease in the bearings before re-installing the landing gear, so I'm not particularly concerned about lubrication in the short term, but I'd like a clean finish. Nothing turns up for Alemite 3018 or 6-40 grease fittings at Aircraft Spruce, and this older Mooneyspace thread on the same topic has no resolution. But there do appear to be suppliers, e.g. https://www.huyett.com/Products/Grease-Fittings-Lubrication/Fittings/Grease-Fittings/A3018. I suspect hangar fairies might also find something suitable at the local aircraft parts and hardware store (which is suspiciously full of car parts...) In the short term, I'm trying to decide whether to cut down a common 6-32 screw short enough to screw it in without interfering with the rotation of the trunion, or just to leave the hole open. The latter actually seems less of a risk.
  9. Vance Harral
    Some important details for those still reading... First, while all the pros thought it fine to put one thin washer on the head side of the bolt, I'd caution against anything more than that. The grip of the bolt (i.e. the length of the non-threaded portion of the shaft) is clearly supposed to extend all the way through both forks of the forked retract truss. The 0.750" grip of an AN26-17 bolt does just that. A single AN960-616L washer draws the bolt head back 0.032", leaving 0.718" of grip, which I was comfortable with based on a visual look - I could still just barely see the edge of the grip shoulder at the surface of the retract link indention. I also tried a standard AN960-616 washer, which has a thickness of 0.063". That results in a grip distance of 0.687". I was uncomfortable with this visually - the thicker washer drew the bolt back far enough that I could no longer see the grip shoulder on the nut side. Based on this observation, swapping the AN26-17 bolt for an AN26-16 would not have been a good solution either, as the grip on the -16 bolt is only 0.688". Second, I double-checked with DMax on this (actually got to talk to Don himself, which was an honor). Don was OK with the washer solution, but said he would probably have just installed a thinner shim behind the "baby shoe" bracket. He also said some airplanes have no shim at all there, just like in my "experiment" video above. In fact, I walked out and looked at another Mooney on the ramp, and it was entirely shim-free - the baby shoe bracket was installed directly against the wing spar strap. I'm still not sure this is a great idea, but I'm really in no position to question Don's expertise. The main reason I didn't go that route is I didn't want to order or machine a thinner shim, and going with no shim at all seemed like it would place too much side load on the bearings during operation. Finally, one mechanic asked why I didn't just install the bolt in the other direction, despite what the parts manual says. We looked into it as a thought experiment, and there are a couple of reasons not to do this. The more important one is there are clearance issues on the other side of the retract truss too, and the consequences of interference on that side would be more severe. The less important one is we came to the conclusion you might be able to remove this bolt and nut without removing the entire landing gear leg, with the parts installed as shown. If you flip the bolt around, it would be absolutely impossible to do so. I still have to re-install the rods and swing arms, then check the gear rigging, so too early to declare victory yet. But good progress today.
  10. Vance Harral
    Update: one AN960-616L washer on the bolt head plus an ever so slight grinding of the bolt tail - taking care to leave plenty of "meat" for the cotter pin hole - gave me the clearance shown below. I'm going to call it good.
  11. Vance Harral
    The advice this morning is to go with a washer behind the head of the bolt, so I'll be giving that a try as soon as I can get out to the hangar. I'll measure the bolt at that time just for grins.
  12. Vance Harral
    I do have a drawing that defines what the stack of hardware should look like - the parts manual for my airplane. There are only four parts: the bolt, nut, bushing, and a single washer that goes on the nut side which you can see in the videos above. I'm pretty confident the stack is assembled per the parts manual, and that it matches what we found during disassembly. But that doesn't necessarily mean it's "correct". As I write this, it occurs to me to look in the M20J parts manual. Our 1976 M20F is kind of a funny airplane. That was the last year of the F, and it was built in the middle of the transition to the J. We've found a few things here and there on the airplane where the assembly corresponds to drawing and parts in the M20J manual rather than the M20F manual. So... the J manual specs the same bushing, nut and cotter pin. But it lists an NAS1106-12D bolt with no washer. The NAS1106-12D is 1-9/64" long, just a skosh longer than the 1-7/64th AN26-17. So doesn't seem like that would help.
  13. Vance Harral
    Thanks for your thoughts, Anthony. The bolt is spec'd in the parts manual, and there is only one size: AN26-17. That's what LASAR shipped. But I agree It looks like it could be shorter. The rule of thumb for lock nuts is at least one full thread showing. I'm not sure what it is for castle nuts, but there are at least two full threads showing here, and as you note, the cotter pin is barely on the edge of the nut rather than snugged down inside the castle groove. Perhaps the answer is simply going to an AN26-16 bolt, which would be 1/8" shorter.
  14. Vance Harral
    For grins, I tried temporarily installing the linkages with the shim behind the "baby shoe" bracket completely removed. This does provide just a tiny bit of clearance, see video below. But I'm still not convinced using a thinner shim (or removing it altogether) is anything but a kludge workaround that doesn't really address the root cause. I'm now wondering if the problem is wear at the interface where the retract truss and the drag link come together over center. That would allow the parts to drop further, and maybe that's why they contact the gear truss. My plan is to call LASAR again tomorrow for further advice, but any thoughts here tonight are also appreciated. I confess I'm a bit demoralized. We're about 10 days into this effort, and it's taking all my free time and some of the time I really should be working at my day job, too... The pitch trim systems are out of the airplane while my partner works on them, so that's hanging over our head, and a lot of the "normal" annual stuff (compression checks, cleaning plugs checking mags, etc.) hasn't even been started yet.
  15. Vance Harral
    Well, the plot thickens. I reinstalled the starboard side gear this morning and couldn't be happier - smooth operation, no slop, plenty of clearance at the bolt, not to mention everything looking cosmetically much better with the newly painted parts and new hardware. When I started putting the port side together - which was the side that was rubbing - the problem is still there. All the slop is gone from the links, but the center pivot point just comes down too far, and bumps the landing gear truss. The video below shows the problem.
  16. Vance Harral
    <raises hand> It's tempting to skip it, because it's a PITA to get the jacket off the muffler down in the lower cowling. But, with stubby screwdrivers and patience, it's possible to slide the jacket sideways, just about completely off the muffler itself, and then do the pressure check. Our mechanic taught us this trick at our first annual 14 years ago, and we've been doing it every year since.
  17. Vance Harral
    Just paint today, other activities (including removal of the pitch trim system) took up most of the day. One quick pic of painted parts. Re-installation begins tomorrow.
  18. Vance Harral
    Interesting observations about wear on the bolts. Completely agree that bolts are prone to wear in fittings where the bushing rotates around the bolt. But when the bushing is supposed to be held captive by the bolt and nut - which I believe to be the case on the landing gear links - wear on the bolt suggests the bolt and nut were not properly tightened in the first place. Might have worked loose or might not have been tightened properly by a mechanic who mis-understood which surface was the bearing surface. What is true is that if the bolt rotates at all, it's likely to wear quickly. There is no hole in these bushings for grease to pass through from the outer to inner diameter of the bushings, and the ends of the bushings are covered by the bolt and nut. So there's really no way to get any kind of lubricant between the bolt and bushing.
  19. Vance Harral
    One of the airplane partners wanted the job done professionally, and had a shop in mind from the get-go. I won't try to justify the $400 charge, but it's not that big a deal split 3 ways across the partnership.
  20. Vance Harral
    Unlikely in this case. Again, the links rotate around the bushings. The bolts do not rotate inside the bushings, they are held captive.
  21. Vance Harral
    In our case, no single bolt/bushing was the obvious primary problem. All had some degree of slop. If you could only replace one of the three, I'd do the one in the middle, at the junction between the drag link and the retract truss - i.e. where the castle nut is that rubs the landing gear leg. However, you're not going to get to that one without completely disassembling the gear as I've shown. In fact, I'm skeptical you can improve much of anything without removing the gear legs. First, while the inboard bolt and bushing (red arrow in my second post) are accessible without doing this, that's only one of the three fasteners. The other two cannot be removed in situ. Second, understand that the wear is primarily between the bushing outer diameter, and the links into which the bushings insert. That's the bearing interface, where the grease goes. The bushings themselves are held captive by the bolts, and the links rotate around them. This is different from more common bushing arrangements where the bearing surface is between the bolt and the inner diameter of the bushing. This outer-diameter-bearing-surface design is the reason why LASAR recommends reaming the links and installing oversize bushings. Just installing a new bushing with the original outer diameter doesn't address the wear on the links themselves. If you absolutely must avoid removing the landing gear legs, I think the only meaningful action you can take is to remove the shim between the "baby shoe" bracket and the strap that connects to the spar (or use a thinner one). That will buy you a little more clearance at the castle nut. But in my opinion it's a kludge fix that doesn't really address the primary problem.
  22. Vance Harral
    Parts came back from the machine shop last night. The bill was $400. If I had it to do all over again, I'd just ship them to LASAR for reaming. $400 seems excessive to me, but to be fair, it was a one-off, expedited job. Here are the parts on the paint bench after final wash and prep, and a coat of primer. Color coat goes on tomorrow.
  23. Vance Harral
    Sorry to hear about your bad engine luck, Stephen.
  24. Vance Harral
    Nice and clean after bead blast. If you're contemplating doing this yourself, make sure you tape off rod ends and springs for blasting. I don't personally think it's that big a deal to get a bead or two in the moving parts as long as you wash them thoroughly in solvent afterward and lubricate them properly before re-installation. But you don't want to directly blast the rod ends or the moving surfaces under the springs. You may or may not be able to tell by zooming in, but the parts aren't really "pristine" with respect to corrosion. There's some very minor pitting here and there, but nothing close to 10% thickness. Mechanic says they look fine to him, and a healthy coat of prime and paint should protect them for another decade or two. I'll start on that when the retract and drag links come back from the machine shop later this week.
  25. Vance Harral
    A lot of what I thought was corrosion turned out to just be "goo" - decades of grease, lubricant, and brake dust mixed with a healthy dose of dirt and other detritus from runways and taxiways. The parts looked much better after a good solvent scrub. But still plenty of missing paint and surface corrosion.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.