Why?

PT6 vs 331?

Garrett does have impressive stats, the price of Pratt overhaul is a downstream factor that must be considered, this is not always the driver in selecting a new power plant during production. There has not been a new airframe I can think of the has used a 331 in over thirty years other than a Caravan retrofit, one of those just crashed after conversion, cause yet to be determined

Exhaust layout makes build and certification easier on the PT6. Free turbine easier on starter generator/electrical system. There are over 40,000 Pratt's out there and there are new airframes being designed around them currently and ongoing engine development. Most shops have seen and worked on a PT6, you can access and work on most components in the field.

A 331 is a mystery to many shops, when it is sick it often goes into a box for a overhaul shop visit. Finding someone that can rig one in the field may require bringing in an experienced technician. You will need to email this technician as he probably won't be able to hear the phone. Only about 13,000 331 were built since the sixties. They did best in airline use, being flown daily, they do not suffer lack of use well.

The 331 is a great engine but, it is more like a Ferrari than a Ford (pricey Ford), not everyone is ready to put up with a Ferrari.

It would be interesting if Garrett put more effort into this engine in the way of development. GE has spurred some interest with its rework of the Walters power plant.


Author reserves right to edit for: Spelin n' Gramuur or stupid thoughts.

A Caravan with Retractable Gear might be nice.

Frank,

RG 208=VG's on a brick.

A 208 is a cargo container with a high lift wing on it with struts, don't think lopping the gear off would buy anymore than aftermarket winglets. Like winglets it would look sexier though.

Sometimes just looking sexy gets you where you need to go.

Correction, large strides may be made with VG's on a brick, did not intend to insult any masons out there.

Mainly Support, service, familiarity.




Why?

They've been working on forms of this since 2010. Looks pretty good too. Bigger than TBM, smaller than a PC-12. A Mustang with a turbo prop. Has the all the systems in place for fast certification.

Somewhere Mike Ciholas posted why the Mustang mule was not a viable production platform. Basically the change in engine weight distribution was going to require a total redesign. (i.e. jets generally have door in front of wing, turboprops have it behind due to required position of wing/fuselage.) That plane probably has a huge ballast weight in the tail. Don't think the mustang will provide much of use to make a SETP.

True about cg weight changes, but if you added a plug to the rear to add a extra seating you end up with this, the one exhaust Beechcraft or is that a Cessna? I guess it doesn't matter now that its all Textron?

This one is photoshop, right? Looks like the prop is on sideways.

+1 It better have a potty like the PC12 too or you can forget about it.

+1 It better have a potty like the PC12 too or you can forget about it.

Certainly ironic, but Cessna has to be one of the most successful OEMs when it comes to building something new on schedule and getting it to market. At least with their jets...

Just because you can't think of it doesn't mean it doesn't happen. New uses of TPE331 in the last 30 years:

Grumman S-2 (Taiwan conversions)
General Atomics MQ-9 Reaper
Comp Air 9
BAE Jetstream 41
Marsh S2R-T Thrush conversion
Marsh Ag Cat conversion
Antonov AN-38
Grob G-520
Kestrel K-350 (pending)
Short Tucano

There just aren't that many new turboprop designs in total, especially twins which are more amenable to TPE331 layout.


Layout on singles is easier for the side exhaust on PT6.


PT-6s can't be rigged by inexperienced technicians, either, if you want good results.


Lots of TPE331 are used in low utilization personal aircraft and they hold up fine. I know of engines which have been operating 30 years without reaching overhaul. There's nothing in the engine design that is particularly sensitive to sitting idle.

Mike C.

Direct from the horses mouth - the Kestrel is still 3-4 years out. No plans to start certification until the Eclipse 550 production is fully funded and cash positive.

I wish Textron would update the KA90 to a modern cockpit. Sat in the "newest" version and the cockpit is like some kind of Frankenstein movie with parts randomly glued together from 1950 analogs to the Collins Fusion.

Epic appears to be getting closer to certification. Kestrel decided to widen their fuselage to differentiate it from the Epic; good choice as the Epic is a bit narrow like a TBM.

I just don't get the interest in a TBM 850, Meridan, Malibu or Piper anything. If I wanted an airplane designed by the marketing department, I'd buy a Duke.