When Is a T-34 Not a T-34?

To paraphrase an old saying, if it looks like a Mentor and it flies like a Mentor, it must be … what the heck is a Preceptor? To answer that question, we looked north to Canada and met Ed and Tyler Butler. Here is the story, told by Ed Butler.

This Fuji LM-1 was part of the project.

In October of 2015, our family purchased a T-34B project which included two T-34Bs, a Beech 33 Bonanza, a Japanese Fuji LM-1, and several boxes of parts. Before we made this purchase, we spent quite a bit of time investigating the requirements needed to meet Transport Canada Aviation’s “Special C of A (Certificate of Airworthiness) Amateur Built.” (Canadian for what we call “Experimental” in the States.) The organization which looks after all Amateur Built projects in Canada for Transport Canada Aviation is the Minister’s Delegate Recreational Aircraft, or simply MDRA. Had we not been able to proceed in the direction of Amateur Built, nothing would have become of it, and any thought of restoring this aircraft in the standard C of A here in Canada would have been financially impossible, let alone the chance to upgrade systems without major involvement with Transport Canada Airworthiness.

The first step in the process is to have the project pass the 51% Major Portion Evaluation—Amateur Built Aircraft. This is done by the MDRA inspector along with the builder. Each item is scored as “other” or “Builder.” The fuselage has 14 items listed, wings have 22, ailerons—9, propulsion—18, empennage—14, landing gear—7, cockpit/interior—6. Once all items are checked off, a tally is made, and the percentage is calculated. Our project scored 61.4%, which gave us the green light to go.

Some basic requirements for getting a Special C of A Amateur Built are as follows:

The plane can no longer have any relationship with the original builder. That is, “Beechcraft” is replaced with “Tyler/Ed Butler” (builder), model number is no longer T-34 Mentor but now is “Preceptor,” and the serial number is now XT-34.

The plane must have a gascolator located in the lowest part of the fuel line between the fuel tank and carburetor.

Must be equipped with a 406 ELT.

Must meet the requirements of Appendix A, Section 549.01 of the Canadian Aviation Regulations, and Chapter 549 of the Airworthiness Manual, Transport Canada.

There are several more requirements, but we won’t include them in this article.

When contacting ATC, we are to call the plane a Preceptor, and if challenged for clarification, we can say, “a full-scale replica of a T-34.”

What follows is an account of what our rebuild consisted of. Remember that we were dealing with pieces of four basic airframes and a garage full of miscellaneous airplane parts.

Let’s Start With the Engine

The Continental O-470L engine was removed from a Cessna 182 with 1,067 hours since major overhaul. The Number 2 cylinder was removed and overhauled, and the existing updraft carb and induction system was removed and replaced with a downdraft setup. The new intake manifold had to be machined from an existing round hole to one resembling an oval tube. A three-quarter-inch aluminum spacer was machined and installed on the manifold to allow for the installation of a new 500 CFM two-barrel Holley carb. A four-inch aluminum riser was made to fit on the Holley, and the carb heat box was bolted onto it. Ahead of the carb heat box, the rear engine baffle was fabricated to fit a four-inch SCAT tube and its associated Turbo Air cleaner. A Tom McNealey mixture control was fitted to the Holley carb, and new mixture and throttle control cables were made to connect the carb to the throttle quadrant. The Holley carb is equipped with a manual choke, thus eliminating the need for a primer. The starter and generator were both replaced with a new C24ST4 starter and new 70-amp alternator.

The hard part of this process was to modify the nacelle, make it more spacious, and increase its structural ability to accept the larger engine. We took the engine and nacelle to Rick West, an old family friend, farmer, aircraft builder (his RV-4 won at Sun ’n Fun), expert in machine shop, engine mechanic, and a genius at figuring out how to deal with the impossible. Changing one thing leads to more changes. The oil pan had to be flattened back 10 inches from the front. The oil filler neck had to be altered 45 degrees to clear the top of the nacelle. The oil cooler on the front of the engine had to be removed, and we had to machine a half-inch aluminum plate equipped with tapped holes to accommodate two new oil lines which connected to a new oil cooler which was installed under the engine in the vicinity of where the O-470L carb was. The air duct which originally connected the front of the nacelle to the original engine induction system was replaced and attached to a new aluminum box, which, in turn, connected to the front of the oil cooler. The front left side of the nacelle had to be modified with an access door so as to service the Number 6 rocker cover. The firewall had to be tubbed out to make room for the Holley carb, as this engine arrangement is much longer than the original.

The original motor mounts were removed, and three from the Beech 33 Bonanza were installed. The fourth, located on the front right side of the engine, had to be machined from new material to match up the engine to the nacelle. Both magnetos were removed. An EFII dual ignition system was installed, with the coil packs mounted on the firewall along with twin manifold pressure sensors. The electronic control units (ECUs) were installed on the right side of the front cockpit. Everything needed to complete the ignition system came with the kit.

We then installed two new fuel cells (not easy), equipped with new Mitchell fuel senders and associated gauges, new aluminum fuel lines, ball valves, Andair gascolator, Facet fuel pumps, a fuel flow sensor, and a fuel pressure sensor.

A Dynon D10 EMS was installed to round out the engine installation. One additional item—a second oil pressure sensor with associated steam gauge—was installed for added peace of mind.

The propeller is a McCauley D3A34C404-8, which was removed from a Cessna 206. The 206 was converted to floats, thus requiring the change of prop. This prop has 233 HSN and 0 SPOH. The coarse pitch was reset to match the O-470L engine. The spinner came with the prop and a four-inch spacer was made to fill the void between the spinner and the engine nacelle.

Next, the Landing Gear

The nose gear was removed from a Beech 33 Bonanza, overhauled, and installed without the steering mechanism, allowing it to caster, and it has proved itself to be a good match. This gear is built much stronger than the original.

The seal on the bottom of the gearbox started leaking oil and had to be replaced. The seal identified on the parts drawing turned out to be no longer available and did not match anything at any of the auto parts stores. Thankfully, the lads at Blackwell Aviation were able to give us the latest version part number, and we ordered it before taking the gearbox out and apart. The new seal had to be shipped from Mexico. Three weeks later it arrived with the invoice: $47 for the seal and $60 for shipping and handling.

We split the gearbox, and, with homemade tools, pulled the old seal out and squeezed in the new seal, actually quite a simple task.

The old seal has a part number on it: “CR15761”. After completing the job, we called the local auto parts store and asked if they might have such a seal, and they said it could be picked up the next afternoon, and the price would be $14, no shipping charge.

So, if you need a seal for your T-34, this is it, or, if you happen to own a three-quarter-ton 1952 Chevy pickup and need a new rear axle seal, this is the one.

The Electrical System

None of the original wiring was reused. The original electrical schematics were used as a guide for building the new system when applicable, but due to the many upgrades, new schematics and associated assignment records had to be created.

Starting at the battery box, two new Odyssey PC680 batteries (weight = 15.4 pounds each) were installed in the existing battery compartment and wired in series to produce 24 VDC. The external plug for the GPU was rewired and terminated on a John Deere 4020 starter solenoid, and from the solenoid a Number 6 cable terminates on a 70-amp master switch, and from the master switch to the 24-volt bus in the 24-volt fuse panel.

One unusual challenge we faced was that we upgraded several systems which did not at the time of purchase operate on 24 volts, only 12 volts. This includes the John Deere solenoid which operates on 12 volts to send 24 volts to the starter. The EFII ignition system, the two Facet fuel pumps, the Mitchell fuel senders and associated gauges, clock, 12-volt electrical receptacle, oil pressure steam gauge, and a future smoke system pump—all had to be addressed. Therefore, two Astron 24- to 12-volt converters were installed behind and to the right side of the rear instrument panel. Each is powered by its own 24-volt/30-amp fuse. The converters are wired to a three-way, 30-amp switch feeding a 12-volt fuse panel. On odd days, the left converter is in operation, and on even days the right is in use. The landing gear motor and indicators, flaps, starter, all lights, radio, and Dynon D10 operate on 24 volts. There are four terminal blocks in the electrical system: a main terminal above the Blue Sea fuse panels, a block behind the rear instrument panel, one behind the front instrument panel, and the original block down by the landing gear transmission. All wire terminations are documented on specific circuit schematics and/or assignment records. This made installing the systems simple, and provided a simple way to trace a problem should one arise. All wiring is tinned copper of appropriate gauge.

Aero-Lites LED landing lights were installed. New electrical conduit was installed in the wings and in various locations in the fuselage to simplify wiring installation and also ensure a comfortable way to replace or add wiring at a later date. We installed a pull string for that reason. The landing gear switch is installed in the front left instrument subpanel. The round knob was attached to the switch with West System and microballoons. The flap switch is also located in this front subpanel. These switches were not installed in the rear cockpit. Except for the radio intercom, no other switches exist in the rear cockpit, so solo is from the front seat only.

The Interior

The rebuild of the interior area of the front and rear cockpits began with the replacement of all the side panels with new aluminum sheet patterned by the ones removed. This aircraft has no magnesium alloy parts remaining. Custom-made instrument panels were cut from 0.125 aluminum. All moving parts within were rebuilt to T-34 specifications. All control cables and associated pulleys were installed new, and all nuts, bolts, and washers as specified in the NAVAIR parts book are new. Both seats were overhauled; the front seat was equipped with an inertia reel—not the back, to save weight—but both sets of rudder pedals can be adjusted front or back by the original hand crank. New seat cushions were custom-made. Both throttle quadrants and trim controls were dismantled and overhauled.

The elevator and rudder trim controls were installed with new cables and set to NAVAIR specifications. Since both fuel tanks flow at the same time, it was decided not to install the aileron trim cables. Instead, each trim tab is ground-adjustable via turnbuckles. Note that after several successful flights, fuel burn does nothing to introduce sideloads on the stick. The front instrument panel is equipped with a Dynon D10 EMS, and in the center is a shelf to support an iPad. An oil pressure steam gauge is located on the upper right side to monitor the engine oil pressure in concert with the EMS. The canopy and windscreen are factory-new; they came with the protective coating still on them. New rollers were installed to complete the canopy installation. The radio, intercom, clock, and 406 ELT are new.

The Tail Section

The tail section of the project has had the magnesium alloy parts replaced with aluminum. We removed the elevator control rods and associated brackets from the Fuji LM-1, then cleaned, inspected, painted them yellow, and installed them. After the rudder and associated trim tab were overhauled and painted, we made the mistake of installing them using clevis pins as it was easy. However, once installed, there was too much play at the hinge points. Checking the parts book, it called for close-tolerance bolts. We used a micrometer to check the diameter of the clevis pin, an Army/Navy (AN) bolt, and then the close-tolerance bolt. The clevis pin was the smallest diameter, followed by the AN bolt, making them both wrong. Call it a learning curve in action again. Now there is no more play. The elevator bellcrank, which we believe was in this T-34, also had unacceptable play. We found that this was caused by the worn bushing. We went back to the Fuji to get the one from it. We found it to be in new condition, so we painted it red and installed it. All moving parts, including the trim tabs, now are set to specifications.

The wings were dismantled, cleaned, overhauled as needed, painted, and installed with mounting bolts, nuts, and washers treated per NAVAIR specifications. The ailerons are aluminum. As noted previously, the aileron trim tabs are ground-adjustable.

Weight and Balance

The other T-34B we have in the barn is a Beech T-34B, serial number BG 405, and we have the logbooks and associated paperwork, including the weight and balance report. This information was used to check similarities regarding weight. The empty weight of 405 is recorded as 2,232 pounds, whereas XT-34 empty weight is 2,047 pounds, lighter by 185 pounds. This plane is in the T-34 utility category and has been approved for a MTOW of 2,985 pounds, with a design weight and balance envelope = 84.1 forward, 90.3 aft.

Taking Flight

This project has taken 10 years to complete, and it surely would not have happened without the help of some truly great friends like Rick West, Mark Seibutis, and Robert Burns. This also includes those we have met through the T-34 Association and the Mentor Monitor itself, especially Dan Blackwell and his excellent articles in the magazine, as well as Tom Mitchell and Chris Link for providing Tyler familiarization flights out of Falcon Field. Special recognition has to go to Jay Sarver for all his expert coaching and guidance along the way, advising what to look for and what to avoid. It is so much appreciated.

Serial number XT-34 is going through the 25 hours within 25 miles of home. We expect the remaining hours to be trouble-free, and if so, it will have the restrictions lifted from the Special C of A Amateur Built. Once the restrictions are lifted, this T-34 will be legal to fly anywhere in the USA and Canada.

The Preceptor is now part of a flying team called “Honour Flight 403” which has been doing formation flights for the past 16 years for RCAF Association Wing 403 in Sarnia, Ontario. This team was formally acknowledged by the Wing and also endorsed by the RCAFA National to give the team this name. We do these flights each year for several Legeans in various towns and cities in southwestern Ontario, for Remembrance Day, Battle of Britain Day, Battle of the Atlantic Day, and other Veteran related activities, which also include flyovers for Veteran funerals if asked by the family to do so.

—Ed Butler

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