Both. All TBMs have a mechanical Left-Right-Off valve controlled by a motor on a timer. You can move it manually or let it switch by itself.

58TC airframe makes a lot more sense than the converted A36 turbines.

For a Cessna wing Would that configuration work out with getting fuel from the aux tanks into the tips and then the tips supplying the selectors to then feed the engine. I think it would take another set of pumps to keep pushing fuel into the tips to refill as the mains? I guess it would be setup as the existing clicker pumps in the tip tanks always on. Aux tank pumps refilling the mains (tips) and boost pumps in the tips(mains) feed supplying the engine? Guess they made it work out somehow.[/quote]

It should be workable on a twin Cessna. The selector valves are in the wings and could be reconfigured to have a transfer position utilizing the existing cross feed port and stainless line that passes through the cabin.

I know one of the production SETP models uses a servo motor actuated auto (timed) selector valve that switches back and forth frequently and the unit costs 40K and is time life limited. An unnecessary and expensive point of failure if you ask me.

The benefit to my system is that all of the useable fuel ends up in one tank and there is never a danger of running a tank dry with fuel remaining in the other. Not a good thing with a free turbine!

Many of the experimental SETPs have had flame outs from air being pulled in from a leaking line, fitting, selector valve or fuel strainer because firewall mounted fuel pumps were used that pull fuel up from the tanks. That is why most production turbines use submersible pumps in the tanks. The SF260T that has a history of flameouts may be an exception. There is no possibility of sucking air in as the entire fuel delivery system is under positive pressure. Air accumulation in the FCU eventually results in a flameout. The Walter powered Lancair IVPs have mostly gone to a header tank that separates and bleeds the air and continuously returns fuel to the tank. It works but is more complex. My system also gives redundancy to the boost pump as either tank can feed directly to the engine.

A Baron is much, much more suitable for a single turbine conversion than a Bonanza. Larger horizontal stabs (with much more robust attachment ) and elevator, larger vertical fin and rudder (with trim tab) designed for asymmetric thrust gives more longitudinal stability w/extended nose, higher VNE, higher gross weight gives much more useful load, much higher fuel capacity (up to 192 gallons in wings on TC and P).

It seems like every turbine Bonanza I see has the Aerotrim rudder trim servo and flexible wire pushrod to the tab added onto the trailing edge of the rudder. Not really something I would want at high true airspeeds at altitude. Last time I read the STC it did not mention rebalancing the control surface after installation.

From a structural standpoint though the Baron wing basically started out with no nacelles on the Bonanza. Twin Cessnas were always twins. With the fuel span loaded and engines on the wings how does that work out in say a 3 G pull-up or gust/wake encounter with the engines gone. The CG of the engine and prop is say 3ft forward of the spar plus the weight 1/4 of the span gone would have to increase the twist and bending on the spar. Plus change the CG of the wing structure assembly towards tail heavy reducing flutter resistance? The Baron would be the same question with engines gone operating at higher speeds and weights than the single. Where is the 5 th attach point. Forward or aft. Is it for rotation about the main gear in a hard landing with the weight of the engines forward or for air loads?

The pics below show how I addressed the change in wing bending moment from unloading by removing engines and nacelles from wings and adding weight to the fuselage. The stepped aft spar doubler was designed by George Braly to strengthen the wing station that lacks structure due to wheel well. The other picture shows the doubler at the main spar (same wing station).

The 5th wing attach point is forward to a false spar and is shear for the higher VNE and also prevents twisting. It is a carry over from the Duke airframe. It utilizes a carry through structure with adjustable eccentric bushings to adjust angle of incidence like single strutted Cessna use. There are additional longitudinal external straps on the belly that tie all three fuselage carry through structures together. Also carried over from the Duke is the 60- part number landing gear components and brakes due to the higher gross weight (6200 lbs) on the TC and P Barons.

Also pictured is the larger tail with robust carry through structures that attach to the front and rear stabilizer spars. The Bonanza utilized a short stamped spar that attaches internally to a tail bulkhead. It is fine for a Bonanza but this is much better for a high performance SETP.

Oscar Taylor converted an Aerostar 602P to a SETP using a TPE331-6. Called it the Speedstar if I recall correctly.

That nose looks nearly identical to a Pilatus

Per the TBM, IMO the TBM was always a production version of a turbine conversion


Wonder how much money they have into this conversion?

This is a Russian version of what you speak of. It is a Walter powered P-Navajo though, not a Cheyenne. It is a good looking aircraft that would have been very easy for Piper to produce.

There are some South African Walter powered SETPs based on a 402 airframe and a Beech Duke.

Info here:

http://www.pilotspost.co.za/arn0000863

I thought it was interesting that it is mentioned in the linked Canadian article that the 421 based SETP is licensed in the amateur built category. This type would have been eligible in the US if not for a particular, now retired FAA safety inspector at the Orlando FSDO.

When the owner of the “341” pictured below applied to him for amateur built certification the inspector turned him down. He had knowledge that the builder of record did not build the aircraft (or have much involvement other than financial) and that it had previously been a Cessna prototype project when a large percentage of the work was performed. An employee of the owner then applied to a DAR without disclosing that the FAA had turned it down.

It was subsequently issued an AB certificate and a waiver to expand the 40 hour test program to encompass Lakeland. A few days later it was displayed at Sun-N-Fun with a sign that said “Yes it is Amateur Built! And we can build one for you”. The FAA inspector and his boss reportedly walked up on it and he was not happy to say the least. He made it his personal mission and vendetta to end the practice. First a moratorium was put in place to restrict designees from licensing any SETP while the 51% checklist was tweaked to disallow any credit for salvaged components such as wings and fuselage from checklist credits.

The airworthiness certificate on the 341 remained in place but the designee lost his DAR status over it.

This is why I come back to beechtalk ha, even though I have zero interest in anything beech.... great read and pics!

I wasn't aware of so many one-off conversions (or that it was feasible in some locations to do it). It was my understanding that converting a certified airframe into an experimental one wasn't typically feasible (and sounds like it's more difficult now than in the past).

But let's say you acquire an older 421 for conversion, maybe for $200k. What's a smaller PT6 cost? $500k? Plus a massive conversion on the airframe, maybe another $200k.

Why would you do this instead of buying a PA46 that burns Jet-A?

In the case of the non certified Walter 601D, the hourly engine amortization is comparable to a big bore Continental. The Canadian 421 is operating in the experimental amateur built category and may be using a PT-6 that does not have the proper pedigree to be used in a certified aircraft. I doubt that they are using a $500,000. engine. A 421B can sometimes be purchased for about the value of the engines so one could conceivably start with near zero costs tied up in an airframe to convert after selling the engines and props.

Found this clip on the South African 402 program. In 2016 they had 4 flying.

https://youtu.be/E-27_xyNhYk?si=MK8QXyQ_rGUoXhlR

Any c.g. change is probably a wash in this case. I'm guessing that the ideal c.g. is at about ¼ chord or perhaps slightly forward of that.

The (twin) pistons are very close to that, slightly in front of it on a small moment arm. The (single) turboprop is lighter than the piston engines but it is also on a relatively longer moment arm.

The SETP for the twin Cessnas means you lose the nose and wing locker storage which is one of the best aspects of these fine bird!

Cool idea though, and I recall drooling over the 340 conversation at Osh many years ago.

Robert

The 421 has two nose baggage doors. In the pic, it looks like the original aft door is still in place.

No comparison between a PA46 and a 421. The 421 is a tank compared to the PA46. Way larger and stronger.

I think a SETP conversion on a 421 is a great idea. The cabin is large and the systems are robust.

Mike

Norman is that a single turbine Duke conversion in your bottom photo? Red white.

Good photos of the spar strap under the engine engine bay area and structure differences.

I have seen a turbine A36 come through here that was also amateur Built.

This is the problem with the FAA. I am told by my local feds I can't even start with a totally bare no paperwork Stinson tube fuselage to build an experimental because it was a certified airplane at one time. Even though I need to build everything else from scratch. I have the drawings, jigs, forms and tooling to do it. Just no paperwork to make it a certified airplane and I want to make some changes so AB would be fine. Yet a quick built 51% kit has many many more completed parts supplied to the builder and a prewelded fuselage. I can easily meet the 51% guidelines but since it was a certified fuselage at one point they say no.
Then you see other people getting AB status on airplanes that they obviously did not build.

That P Navajo with single turbine looks way better than a Meridian. Better cabin and more robust airframe.