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Archive for the ‘Main Landing Gear’ Category

Drilled Right Main Gear Axle for Cotter Pin – 1 hr

December 14, 2012 Leave a comment

Friday Dec 14, 2012

Tonight I drilled the right main gear axle for the cotter pin. The process was just like last night except on the opposite gear leg. No pictures.

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Drilling Axles for Cotter Pins – 2 hrs

December 13, 2012 Leave a comment

Thursday Dec 13, 2012

The nose gear has a couple of big belleville washers that preload the vertical pivot bearing axially. This eliminates slop but more importantly causes frictional damping to prevents the nose wheel from doing the shimmy at high speeds. The level of preload is set by adjusting the pivot bearing nut until the breakaway drag on the pivot bearing is about 22 lbs measured along the wheel centerline. The scale for measuring this does not come with the kit so I went on Amazon and found a digital luggage scale that measures up to 75 lbs. It was only about $7 so I ordered it about a month ago anticipating this day. I can also use it to weigh luggage.

Here is my setup for measuring the breakaway friction of the pivot bearing. I used safety wire to make a loops that attach to the nose gear fairing brackets on each side. The nose wheel is off the ground in this photo about an inch so the pivot axle is vertical. I adjusted the nut until the breakaway force was about 22 lbs in each direction then I rotated the wheel through +/-30 or so about fifty times to make sure everything was seated and rubbing surfaces were broken in. Then I readjusted the nut for 22 lbs again. In repeated measurements the results varied somewhat but in the end I measured about 22 lbs in one direction and about 24 in the other direction with each measurement varying about +/-0.5 lbs from one measurement to the next. Then I drilled the holes in the axle for the cotter pin. That was a pain in the neck. The axle is steel and it is pretty hard. Going at low rpms and using plenty of lube it took quite a while to drill through each side and I broke one drill in the process. Nevertheless I got the holes drilled and deburred and the nose gear is now permanently mounted to the axle with the cotter pin installed.

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For the main landing gear I had to raise the nose of the fuselage slightly with the crane to get the weight off the gear. I started with the left main gear. These use tapered roller bearings with seals that offer a fair amount on rolling resistance (at least until the seals wear in a bit). The objective here is to tighten the axle nuts enough to remove all axial play in the bearings but not so tight as to cause excessive loads on the bearings. The Matco instructions say to tighten the nut until the seals no longer rotate with the wheel as it is turned then tighten to the next cotter pin position. Well, there are no cotter pin positions yet because they are not predrilled so I tightened the nut about 15-20 degrees past where the seal stopped turning. I also checked to make sure there was no freeplay in the bearings at this preload. Then I started drilling with a 12 inch #30 drill through one of the pin holes of the nut. Once I drilled far enough that the hole center was well established I took the nut and wheel off the axle and finished drill through the first side with a new 1/8 inch cobalt drill bit. I cleaned up the burrs and reassembled it to set up to drill the opposite side. To make sure the hole I just drilled was aligned to the hole in the nut I pushed a 1/8 inch solid rivet though the aligned holes in the nut and the axle to key them together before drilling on the other side. Then I repeated the drilling process for the opposite hole starting with the 12 inch #30 drill until the hole center was well established. After I took the wheel off again and had drilled through the axle I ran the drill through both holes at the same time to make sure the cotter pin could pass through both sides. Then I just cleaned up the burrs with a tiny jewelers file and put it all back together again. The cotter pin is currently slipped through but I won’t bend it until I am satisfied the wheel is staying on.

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This Bird Has Legs – 8 hrs

December 1, 2012 Leave a comment

Saturday Dec 1, 2012

Today was one of those rare days where a bunch of significant things were completed. I started this morning working on the ELT mount. The parts needed to be primed so I scrubbed all the parts with Simple Green, rinsed and dried them. The weather was not great this morning and the humidity was kind of high but I was able to get a decent coat of primer shot onto the parts in the paint booth. After drying a while I riveted them together with the nutplates for the ELT tray. Here is the bracket by itself.

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And here is how it looks with the ELT tray installed. The ELT traps are clamped down under the tray by the mounting screws.

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I installed the bracket with the tray attached into the fuselage using CS4-4 pop rivets and installed the ELT to the tray. I’m guessing it is stiffer than the Vans bracket because it ties directly into those stringers without the large flat surface of the Vans bracket. This mount sure seems stiff. It also does not interfere with the rudder cable and it keeps the center of gravity as far forward as possible.

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Next I installed the Dynon remote transponder unit. It also has a tray which I mounted with three screws to the center rib behind the pitch autopilot servo. I drilled the holes in the rib and used locknuts to install it. This did not take long once I got my less-than-flexible body back there where I could reach this area. The transponder just snapped into the tray with a wire retaining clamp on the aft end. Next step with the ELT and transponder will be making coax cables and running wiring.

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Several months ago I purchased an engine crane at Harbor Freight in preparation for hanging the engine. Today was the day that I opened the crate and assembled this thing. It took about 45 minutes to put all the pieces together and get it operating. I have to say I am impressed with the quality of this thing. It lists for $200 but I bought it with a HF coupon for $100 and at that price it is a steal. It is perfect for this job and it looks pretty good too. I just wish I had more space to store it.

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I didn’t really plan this in advance but since I had the crane operating I lashed it to the engine mount and lifted the front end of the fuselage. That gave me enough clearance to insert the nose gear which has just been sitting in the corner anyway. I had to jiggle it quite a bit to get the bolt hole aligned but I got it in. At that point I had to decide to go ahead and put the two main gear legs on or remove the nose gear for another day. I thought, “It’s time to give this bird some legs.” With the crane attached I just lifted the front a little further and I could slide the main gear legs into the sockets and bolt them in. Wow, it is cool that this is done – it’s a major milestone.

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One lesson learned – I buggered up the threads on one of the gear leg bolts trying to get it in before the holes were perfectly lined up. After that I got smarter and went to the hardware store a picked up a 3-inch long, 5/16 diameter bolt that I ground down to make a tapered drift pin (see below). Once I got the holes close I tapped this pin in to center everything up before installing the real bolt. I will have to order a replacement for the one bolt I buggered.

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Repacked Wheel Bearings – 1.5 hrs

October 24, 2012 Leave a comment

Wednesday Oct 24, 2012

I originally hand packed the main landing gear tapered roller bearings with grease  but I had lingering concerns that they may not be fully packed. After all, I’m not an experienced packer. So I ordered this Lisle bearing packer from Amazon for about $10. A good investment in my book. I also ordered a grease gun which I need to fill the nose gear swivel bearing anyway. I could have bought a grease gun at Home Depot for $15 but the one I bought is way better quality for $18.

The packing process is simple. You sandwich the bearing between the upper and lower cones and then pump grease into the bearing through the center screw with a zerk fitting attached.  When you see the grease oozing out between the rollers the bearing is packed.

I also decided to modify the right F-745 rib of the front fuselage structure to permit the installation of a second 10-inch Skyview display. So I cut the rib at the front surface of the sub-panel and touched up the edge with paint. When I clecoed the rib back into the fuselage it made it symmetric with the left side. So later I will make angles to mount the remaining aft sections of the two F-745 ribs to the subpanel closer to the centerline between the Skyview and the radio stack.

Finished Riveting Top Fuselage Skin – 3 hrs

October 20, 2012 Leave a comment

Saturday Oct 20, 2012

Working solo today I finished riveting the top forward skin on the fuselage. The rivets I shot were the vertical column on the left over the top and the horizontal row illustrated below by the red arrows.

The three forward-most rivets on each side are pulled Cherrymax rivets because there is no way to get behind there to buck solid rivets.

I also installed the brake line fittings on the calipers using some Loctite 567 sealant on the threads.

Left Main Landing Gear – 1.5 hrs

August 11, 2012 Leave a comment

Saturday, Aug 11, 2012

Progress has slowed to a crawl because things unrelated to the airplane project have demanded my attention the last few weeks and it will continue for a while. In addition, I will be away on my 25th anniversary trip for 3 weeks so expect a hiatus in the postings.

With that said today I made a little progress on the right main landing gear. In the last post I reported that the left axle is a little oversize and the bearings would not go on. So today I used emery cloth to buff about .001 inch off the diameter of the axle. I went around buffing like I was shining a shoe rotating in about 90 degree increments to cover the entire diameter from the threads to the shoulder. After a while I had victory and the bearing slipped on, but just barely.

Then I made three more spacers from 3/8 diameter tube for the wheel pant support bracket. These are probably too long but I can shorten them later when the bracket is fit.

Next I packed the two wheel bearings with Aeroshell 5 grease and installed the wheel onto the axle. The nut did not want to thread on so I spent some time cleaning the threads on the axle after which the nut went on OK.

Main Landing Gear Wheels and Brakes – 4 hrs

August 5, 2012 Leave a comment

Sunday Aug 5, 2012

Well it’s been about a week since I did much of anything productive on the project. I promised Denise I would rebuild the patio cover this summer. It was rotting and I took it down last fall for safety. So I spent some time over the last week putting most of the primary structure back up with new lumber.

Life also has been getting in the way. My mother is very ill, a daughter is planning a wedding, and Denise and I are planning for our 25th anniversary trip to Europe this month. Too much going on.

Anyway, I thought assembling the wheels and brakes would be a quick, straightforward task that I could knock out in a day. I guess I was wrong, but I am getting ahead of myself. I spent way more time than expected searching for the parts in all the various kit boxes. Sometimes it is not obvious where the parts are located. After finding the U-403 flanges I drilled the cross holes out with a 5/16 bit and reamer. The U-403 would not fit onto the axles so I had to smooth out the interior and edges to get them on. Then I searched and finally found the special socket head shoulder bolts for these in the fuselage kit. The plans say to start by bolting the U-403 on so that is what I did.

Then I learned that you can’t put the brake flange on with the U-403 already installed. Why didn’t they tell me that? So I took the U-403 back off and reassembled it with the disc brake flange between the bolt and the U-403 flange. Oh, and that is after spending way too much time trying to figure out the correct orientation for the brake flange and bolts. Here is one gear leg close up.

Then came the assembly of the wheels and tires. The plans are brief here but I found enough help on the web to get them assembled except I could not find the grommets that are supposed to go in the filler valve holes. I will look again for those later I guess.

Then I repacked the bearings for the right wheel with Aeroshell 5 grease and installed the wheel on the axle. I have not drilled for the cotter pin yet because I want to make sure I have the torquing procedure correct (and I ran out of time). Here is a view from the axle nut side.

And this view is from the brake disc side. I forgot to mention that I made three spacers tubular for the wheel fairing bracket using 3/8 tube and installed the brake flange using these but I will install the fairing bracket at a later date.

The other axle was completely different story. I tried to put the bearings on but they would not go on the axle. For some reason the left axle is slightly oversize (by my caliper measurement I am estimating about .001 inch oversize). I tried pressing but the bearing got stuck and I had a tough time getting it back off. I used some emery paper to polish up the OD of the axle but that was not enough to get the bearings on. I’ll have to do some research on this.

Followup: I found a thread on Vans Air Force about this problem from the 2007-2008 time frame. I guess the problem is back. The solution is either to call Vans and insist on a replacement gear leg or to polish the axle down to size using crocus or emery cloth. Since the gear leg is already drilled to my fuselage I will try the emery cloth approach before calling Vans.