·:[ Darryl's Coot Building Journal ]:·
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Between us, Russ Milham and I have three engines to rebuild. I have a Franklin 165 (6A4-165-B3) to rebuild for my Coot, Russ has his Continental O300 to rebuild for his Coot, and we jointly own a Lycoming 0320 for our Traveler project that needs rebuilding.

We looked at commercially available engine overhaul stands (example) and found that they cost about $200 for a basic stand, and a little less for a kit. These are probably fine, but we wanted a stand that could be disassembled and stashed away when not in use—shop space is getting scarce! And we wanted a stand that can be used with a variety of prop flange bolt patterns, and had more than two holes for bolting the prop flange to the stand. I agreed to undertake the project.

This post shows the construction of the stand. Rather than providing technical drawings, I’ll explain things with text, measurements, and photos, which should be ample information for others to build a similar stand. Here is what the stand looks like completed:

Bill of materials:

1. One 7″ x 7″ x 0.125″ (11 gauge) mild steel sheet (prop flange plate)
2. Three 3″ x 3″ x 0.125″ (11 gauge) mild steel sheet (foot pads)
3. Three 1.25″ x 1.25″ x 0.25″ x 36″ mild steel angle (legs)
4. Two 0.125″ x 1″ x 72″ rectangle mild steel (cut into cross-braces)
5. One 1.5″ x 2″ x ~6″ block of steel or aluminum (shim fabrication)
6. Twelve 3/8″ x 1″ grade-8 bolt, washer, lock washer, nut set
7. Twelve 5/16″ x 1.25″ grade-8 bolt, washer, lock washer, nut set
8. As required, metal primer and paint

Legs: The legs are constructed as two nested pieces that are bolted together, so that the stand can be disassembled into a relatively compact form. The short leg pieces are about 5.5″ long and the long pieces are about 31″ long. The -3 legs are cut at a 55 degree angle. A single cut is made at 5″ from one end and the cut is toward the long end.

(Another view.)

Here is how I cut the angle using a metal cutting bandsaw. A piece of angle aluminum was put into the vice to hold the angle steel at a 45 degree angle in the saw’s vice.

…and the vice was rotated to 55 degrees:

This one cut, thus, sets the proper angle for the stubby legs (that are welded to the flange plate), and the long legs (that are welded to the foot pads).

Prop flange plate: The prop flange must bolt to the top of the engine stand. This requires machining plate steel, to turn a rectangular plate into a circle (although you could skip this, if you wanted) and machining slots for bolts. I used 1/8″ steel for the flange plate, which works perfectly fine. You can go thicker, but don’t go any thinner.

First a note about prop bolt patterns. There are three commonly-used prop bolt patterns for small aircraft engines. I recommend machining slots that will provide for all three patterns. The standards come from SAE AS127D, #1, #2, and #3. Numbers 1 and 2 are used on Lycoming and Continental engines and are 6-bolt patterns, and #3 is used on Franklin engines and is an 8-bolt pattern. The bolts for all three are 0.375 (3/8″) diameter, and the flange pilot (the central protrusion from the flange) is 2.249″ in diameter for all three patterns.

Here is a sketch of how the plate can be machined:

The face includes a 6-bolt pattern with a circle diameter of 4.375″ for #1 and 4.75″ for #2 patterns. The pattern also incorporates four (of eight) bolts for the #3 (Franklin) pattern, with a bolt circle diameter of 5.25″.

So here is are the holes:

• Two 3/8″ slots from 4.1875″ to 5.4375″ diameter (these are the horizontal slots that are used for all three patterns)
• Two 3/8″ holes at 5.25″ diameter at 90 degrees from the first two slots (two vertically aligned holes that are used for the Franklin prop pattern)
• Four 3/8″ slots from 4.1875″ to 4.9375″ diameter at plus and minus 120 degrees of the first two slots

Note that you can make the slots longer. For example the four slots can go from 4″ to 5″, without problems, but don’t make the holes much bigger that 0.375″ (3/8″). The bushing diameter on the prop flange is 0.623″, and the six or eight bushings are the only contact between the engine and the stand.

Here is the sequence of machining:

First, beginning with a 7″ x 7″ plate, bore a 2.5″ pilot hole in the center of the plate. I held the plate in a four-jaw lathe chuck and located the exact center:

Then a pilot hole was drilled, and a hole of about 1″ was drilled. A 2.25″ pilot was then bored into the plate:

Once the pilot hole is finished, the four-jaw chuck is replaced by a three-jaw chuck to hold the plate by the pilot hole. And the square plate is machined into a round plate:

(I started machining the corners and realized it was going to take awhile. So I switched to a thick cut-off bit and came in from the side. Slow the lathe down near the end to prevent the corners from flying too far.)

The next step is to machine slots and holes into the flange plate:

Tripod Assembly: The next step is to weld the short legs onto the flange plate:

(More views here and here.)

The long legs can then be fitted to the small tripod. The long legs are fitted to the inside of the short legs. I used a belt sander to round the outer angle of the legs slightl where they overlap the short legs. This allows them to nest snugly.

Using clamps to hold the legs in place, move the long legs up and down until the top of the stand is perfectly level. Don’t skimp here!

(Another view here.)

…and drill four 3/8″ bolts to hold the legs together:

Next cut three 3″ squares of 0.125″ steel, and weld them on.

Bracing: Next comes bracing. There are several ways to do this, so feel free to figure out your own way. I chose to add two “layers” of bracing, one near the top and one near the bottom. I cut three pieces of 1″ x 0.125″ rectangle for each. Here they are resting in place:

(Another view here.)

Since the angle of the legs is 90 degrees, but the legs are spread 120 degrees apart, shims are necessary between the bracing and the legs. I chose to saw the shims out of a block of aluminum I had sitting around. Use whatever works for you. Here is a shim being test-fitted.

Slight asymmetries in the angle at which each leg was welded to the prop flange plate necessitated custom shim thicknesses.

Now, use C-clamps to hold the whole thing together and drill holes for the 5/16″ bolts. Here is the entire thing assembled (before trimming of the shims) with 350 pounds of semi-static load (I was bouncing a bit). The stand is rock solid.

The next step was to trim the shims, and stamp a label where everything fits, so it can all be reassembled without difficulty.

Finishing: The last step is painting the stand. The top of the prop flange probably shouldn’t be painted or else you may end up scraping paint off of the prop bushings after a rebuild.

I brushed on RustOleum metal primer (here and here) and then sprayed on a RustOleum enamel textured white.

(Another view here.)

Here is the assembled stand:

Using it: Within a week of finishing the stand, Russ and I had mounted the engine on it and pulled cylinders, pistons, and connecting rods. Splitting the case comes next….

(Another view here.)

This is part III of a series on N5814L, a 1972 AA-5 Traveler. Two weekends ago, we prepared the plane for trailering from Dave Wheeler’s Northwest Aviation at AWO to co-owner Russ Milham’s shop just north of Seattle.

Our adventures in trailering began with trying to find a suitable trailer. I posted a query on a regional aviation forum. A person named dww generously offered us his trailer, although it required a weekday pick-up an a bit of work to make roadworthy. The weekday pick-up proved to be difficult, because I don’t have a vehicle with a trailer hitch, and Russ’ vehicle wasn’t available during the week. But I also found a trailer for rent via Craigslist that was two minutes away from the airport.

Our trailering plans got put on hold for a week owning to an insurance snafu. Schedules didn’t allow us to get started until Saturday, mid-afternoon. When Russ showed up to pick up the Craigslist trailer, it was smaller than described and probably wasn’t going to work very well. Uh-oh. On top of that, the guy wasn’t willing to wait for Russ to do some measurements on the airplane and come back. Russ walked away.

I called an old friend, Richard V., who lives in nearby Marysville. Richard is a homebuilder with lots of connections in the local aviation community. His response? “I have a tilt bed trailer right here you can use. Come on over.” Wow!

After a few minutes rigging up an adaptor cable for the lights, we were on our way.

The Traveler is 8′3″ wide between the main gear tire midlines. We stopped by a lumber store and got a 2×8 cut to 8′6″, the maximum width allowed for a normal width trailer. With a little scrap lumber from a nearby dumpster, we rigged up a ramp.

(Another view.)

A couple of come-alongs were used to winch the plane into the trailer. The nylon strap from one winch was passed through the spar tube.

(Another view.)

The next step was to strap down the tail. Notice the 2×8 with a furniture pad underneath on top of the tail attach point. There is plenty of bendable aluminum in this area:

(Another view.)

…and lowering the bed of the trailer.

(Another view.)

The winches were replaced by cargo straps through and around the spar. A second strap was added to the tail, and engine components were secured with tie-wraps and covered in plastic and duct tape.

Finally, the wings were stacked under the fuselage with furniture pads in between. And the horizontal tail section was stacked on top of the wings.

(Other views: here, here, here, here, here.)

The road trip was uneventful. On our 30 mile trek down the I-5 corridor, we were passed by three police cars who, apparently, didn’t find it the least bit suspicious to be trailering an airplane under the cloak of darkness.

Unloading the plane was relatively simple using a thick piece of plywood as a ramp.

(Another view.)

The Eagle has landed.

The next stop was my house, where Russ dropped off the left wing and trailer. The day was a success, if a little on the long side—we end at about 1:00 a.m. Sunday. But quite a haul!

It was Saturday morning, 14 March 2009, and Russ Milham, a bunch of friends and I showed up at Northwest Aviation at AWO to dismantle N5814L, a 1972 Traveler, for trailering.

All of the photos in this post were taken by Steve Johnson, who also did a lot of disassembly work.

Here she is as we left her after inspection:

Here’s Russ surveilling the task ahead of us. Notice that cylinder one and its piston have been removed—that was from an inspection. We’re rebuilding the engine, so the rod was secured in a bed of cardboard for transportation.

And here I am bagging the lose stuff in the cabin.

The vertical fin is removed. You can see a person under the inboard end of each wing dealing with fuel lines and electrical connections in preparation for wing removal.

Following the service manual instructions was mostly helpful…as was the occasional swig of coffee.

My friend Tim Lange pulled the carburetor and alternator. The carb was sent out to a rebuilder the following Monday.

The last step was pulling the wings off, a process that required five people. One person was in the cabin to deal with the exiting torque tubes, two people were stationed at the outboard end and two at the inboard end. The idea was to engage in a coordinated rotation of the wing, with a bit of up-down rock to find the sweet spot where friction is minimized between the center-section spar and the wing spar.

We first tried the left wing. It was stubborn, but with persistent rocking the root eventually started pulling away from the plane 0.1 mm at a time. The first inch required about 90% of the effort. After that it was pretty simple. The right wing came off with no difficulties.

Steve was helping to pull the wing, so there are no photos of the process. Here’s the aftermath, with Russ and me tucking 14L into a corner.

All put away and awaiting a trailer….

We loaded everything but the horizontal tail section, the two wings, and the hull into our cars, and headed off into the sunset. Next post: Trailering a Traveler.

A couple of months ago, my Coot-building buddy, Russ Milham, and I were visiting Dave Wheeler and Northwest Aviation at their new location at the Arlington Municipal Airport (AWO). In one corner of the shop, we spotted some type of Grumman four seater.

We looked over the plane, an early AA5 Traveler, as Dave Wheeler explained that his shop was assessing the plane’s value for an estate. As it happens, Russ and I had been talking about a partnership in a 4-seater of some type. The AA5 family was definitely on our list. We took a closer look:

Don’t get me wrong…I love my Yankee, and it satisfies my mission about 80% of the time (solo local, solo cross-country, two-people locally). But the Yankee’s limited endurance with a passenger, limits on passenger weight, and limits on passenger height (to about 6′2″), sometimes gets in the way.

Anyway, Russ and I made a deal with Dave…we would do much of the labor required to inspect and assess the plane. That would give us a chance to do our private valuation, and the estate would get a less-expensive valuation. If we liked what we found, we would make an offer. Oh…I should mention that Russ is an A&P mechanic.

N5814L is a 1972 AA-5 Traveler, serial number 14. Based on on-board paperwork and logbooks, the plane has not flown since sometime around 2001. The interior is…well, old:

The panel is pretty basic and very dated. We didn’t evaluate any of the avionics, except to note that the ELT was missing.

Russ and I spend a couple of weekends opening up the plane and performing inspections. Our squawk list was long. There was a potentially un-reparable left aileron. Both fuel tanks leaked, a problem that requires an enormous amount of labor to repair. Shops charge may thousands of dollars per wing for resealing these tanks.

The engine needs an overhaul. It had had a field overhaul in 1994, but we had no paperwork whatsoever, aside from an insufficient log entry—no yellow tags for components or record of dimensional inspections. Either way, the engine has been sitting for eight years and is past Lycoming’s TBO of 12 years.

We made an offer to the estate. Dave Wheeler had assessed a similar value, and everything got passed onto the to estate. For several reasons, it took about five weeks for the estate to accept our offer and ensure a trouble-free transfer of ownership.

Last Saturday Russ and I bought the plane. We will do much of the work to return 14L to service ourselves. For starters, Russ is rebuilding the engine, and I am going to work on resealing the fuel tanks. (Of course, we’ll be shipping engine components out for proper measurement, inspection, and rebuild.) Most of the plane goes to Russ’ shop, whereas I get one wing at a time, and sort some of the components in mine.

Next installment…dismantling for trailering the plane.