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The SOCATA TBM & Pilatus PC-12

v1.0.1 / 01 mar 14 / greg goebel / public domain

* From the 1980s, a number of firms have introduced single-engine turboprop executive aircraft, the most prominent of them being the French SOCATA TBM and the Swiss Pilatus PC-12. This document provides a history and description of the TBM and PC-12; it also lists a number of comparable aircraft that have not been as successful.

Pilatus PC-12


[1] SOCATA TBM
[2] PILATUS PC-12
[3] COMMENTS, SOURCES, & REVISION HISTORY

[1] SOCATA TBM

* The Morane-Saulnier company of France was a player in aviation from before the First World War. In 1962 Morane-Saulnier was bought out by Potez, which was bought out in turn in 1966 by Sud Aviation, later Aerospatiale -- the Morane-Saulnier unit being renamed "SOCATA", for "Societe de Construction d'Avions de Tourisme et d'Affaires (Company for the Construction of Aircraft for Tourism & Business)". SOCATA focused primarily on development and production of tidy light single-engine civil aircraft, such as the "TB" series -- named after the French city of Tarbes, where the SOCATA plant was located.

In the early 1980s, the US Mooney civil aircraft firm developed a six-seat piston single, the "Mooney 301". The 301 would never go beyond a single flight prototype, which performed its initial flight in 1983, but Mooney was bought out by French investors in 1985, leading to discussions between Mooney and SOCATA for development of a turboprop derivative. A joint venture was set up in 1987 to build the "TBM (Tarbes-Mooney)" turboprop, with initial flight of the first of three prototypes on 14 July 1988, certification following in 1990. Financial problems forced Mooney to withdraw from the program, but the aircraft retained the "TBM" designation.

* The initial production variant, the "TBM 700", provides a baseline for the series. The TBM 700 was an elegant aircraft, built mostly of aircraft aluminum alloy and steel, with some use of plastic and composites. It featured straight wings and tailplane, along with a swept tailfin featuring a forward fillet. Flight surfaces were conventional, with ailerons, elevators, rudder, trim tabs, and one-piece flaps; there was a spoiler forward of the outboard half of each flap. Flight controls were manual, except for electrically actuated trim tabs and flaps. There were twin fixed ventral fins under the tail. The TBM 700 had tricycle landing gear, all gear with single wheels, the nose gear retracting backward and the main gearing hinging in the wings towards the fuselage.

SOCATA TBM

The TBM 700 was powered by a Pratt & Whitney Canada (PWC) PT6A-64 turboprop, with 522 kW (700 SHP), driving a four-bladed, fully reversible Hartzell propeller. There was a fuel tank in each wing, each tank with its own refueling point, the two tanks providing a total capacity of 1,080 liters (285 US gallons). The TBM 700 had pressurized and climate-conditioned accommodations, with seating for two pilots -- dual controls were standard -- and four passengers, the passengers facing each other front to back. Sources show diagrams of a a high-density layout with five passenger seats, with three rows of seats and the middle row with one seat, but it doesn't seem to have been popular. Baggage storage was in the rear of the passenger cabin, and in an unpressurized baggage hold in the nose of the aircraft forward of the cockpit; sources seem to hint that the unpressurized hold was added in later production. There was a passenger-crew door on the left rear fuselage, the door being split up and down, with the lower segment featuring an "airstair".

   SOCATA TBM 700:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                12.16 meters        39 feet 11 inches
   wing area               28 sq_meters        193.75 sq_feet   
   length                  10.43 meters        34 feet 2 inches
   height                  3.99 meters         13 feet 1 inch

   empty weight            1,825 kilograms     4,025 pounds
   MTO weight              2,990 kilograms     6,595 pounds

   max cruise speed        555 KPH             345 MPH / 300 KT
   service ceiling         9,150 meters        30,000 feet
   takeoff run             865 meters          2,850 feet
   range                   2,985 kilometers    1,855 MI / 1,610 NMI
   _____________________   _________________   _______________________

The prop was electrically deiced; the windscreen was deiced both electrically and by bleed air; and all flight surfaces had pneumatic deicing boots. Avionics were conventional, including radio, identification transponder, autopilot, and navigation system. The navigation system had a global positioning system (GPS) option. Weather radar was also available as an option, the radar being mounted in a fairing outboard on the leading edge of the left wing.

The split rear door was replaced in 1998 by a large upward-opening door with tilt-down steps. A quick-change configuration was available as an option, allowing the seats to be yanked for carrying cargo, the reinforced floor featuring tie-downs. Maximum cargo load was 825 kilograms (1,820 pounds). There was also a configuration with two instead of four passenger seats to permit more cargo carriage, though it is unclear if this was a special option or, more likely, if it was just the standard configuration with the two rear seats removed. TBMs configured for cargo operations also featured an optional cockpit door on the left.

The TBM 700 was sold in a number of subvariants. Sources are notably confused and confusing in their descriptions, but it appears that the sequence was as follows:

The French Air Force and Army bought a total of 26 TBM 700s for liaison duties. Work on a stretched variant, the "TBM 700S", was abandoned in the mid-1990s. There was also a concept for a high-altitude surveillance / research derivative, the "SOCATA 60000", with greatly extended flight surfaces, but it never went beyond the paper stage.

SOCATA TBM of Armee de l'Air

* In 2004, SOCATA began work on a next-generation TBM, originally designated the "TBM 700N". The second TBM 700 prototype was updated as the 700N prototype, performing its initial flight in February 2005, and then entering production in 2006 as the "TBM 850". It replaced the TBM 700 in production; it was much the same in configuration, the major improvement being a PWC PT6A-66D engine with 635 kW (850 SHP) for higher cruise speed -- oddly, there was no increase in takeoff power -- and enlarged fuel tanks. From 2008, it was sold with the Garmin G1000 "glass cockpit".

SOCATA has offered the TBM series in special mission configurations, for air ambulance, photo survey, target tug, maritime patrol, surveillance, and electronic warfare (EW) missions. The company demonstrated a machine for photo survey, with a belly camera pack; has also demonstrated an air ambulance configuration; and has sold at least one "multimission" TBM with a retractable imager turret under the rear fuselage to Argentine security police. A total of well over 500 TBMs has been sold to date. SOCATA became part of the European Aerospace & Defense Systems (EADS) group in 2000 when Aerospatiale was absorbed into the conglomerate, but the SOCATA operation was sold off to Daher in 2008, and so the operation is now "Daher SOCATA".

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[2] PILATUS PC-12

* The Pilatus company of Switzerland was established shortly after the outbreak of World War II, at the outset focusing mostly on maintenance and assembly of existing aircraft types. The first aircraft of significance produced by Pilatus was the "P-2" piston trainer of 1945, followed early in the next decade by the improved "P-3" piston trainer. In the mid-1950s, Pilatus introduced the best-selling "PC-6 Porter" utility aircraft, and in the early 1970s introduced the similarly popular "PC-7" turbo trainer, derived from the P-3.

In the late 1980s, Pilatus began investigation of a turboprop-powered utility aircraft, only to find their efforts trumped by the popular Cessna Caravan. They shifted their sights to a turboprop business aircraft, formally launching the "PC-12" program in 1989. Initial flight of the prototype was on 31 May 1991. Trials going well, certification was obtained in 1994, with deliveries before the end of the year.

Pilatus PC-12

The PC-12 has a low wing with winglets, a tee tail with a dorsal fillet, and tricycle landing gear -- hydraulically activated, all single wheels, the steerable nose gear retracting back, the main gear retracting in from the wings. The initial production PC-12 was powered by a PWC PT6A-67B turboprop, providing 1,200 kW (1,605 SHP) and driving a four-bladed Hartzell propeller. The PC-12 is mostly made of aircraft metal but has some composite parts, such as the winglets. The flight surfaces are pneumatically de-iced, while the windscreen and prop are electrically de-iced.

   PILATUS PC-12:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                16.08 meters        52 feet 9 inches
   wing area               25.8 sq_meters      277.8 sq_feet   
   length                  14.38 meters        47 feet 2 inches
   height                  4.26 meters         14 feet

   empty weight            2,386 kilograms     5,260 pounds
   MTO weight              4,000 kilograms     8,820 pounds

   max speed at altitude   500 KPH             310 MPH / 270 KT
   service ceiling         10,670 meters       35,000 feet
   takeoff run             680 meters          2,230 feet
   range                   3,310 kilometers    2,060 MI / 1,790 NMI
   _____________________   _________________   _______________________

An optional Honeywell weather radar pod can be fitted on the right wingtip. The aircraft has a fold-down airstair door on the left side of the fuselage, with a large upward-opening cargo door at the rear on the same side; there is an emergency exit above the wing on the right side. The PC-12 features a reinforced floor for cargo hauling. Flight crew is one or two.

Various configurations were offered:

* A variant of the PC-12 with gross weight increased from 4,000 to 4,500 kilograms (8,820 to 9,920 pounds) was certified in 1996 and became production standard in 1997, with this version known as the "PC-12/45". There was consideration in that timeframe of "PC-12/44" powered by twin Williams turbofans on wingtop pylons, but it didn't happen. Another improved variant with gross weight increased to 4,740 kilograms (10,450 pounds) was introduced in 2006, with the designation of "PC-12/47". The PC-12/47 could either handle 240 kilograms (530 pounds) more payload or extend its range by 650 kilometers (400 miles / 350 NMI).

Pilatus PC-12

By 2013, over 1,200 PC-12s of all types had been sold. The latest version of the PC-12 is the "PC-12 Next Generation (NG)", which features a redesigned cockpit with a Honeywell Primus Apex avionics system built around four color flat-panel displays, plus an updated PWC PT6A-67P turboprop engine, it seems with better high-altitude performance for faster cruise speed. The PC-12 NG was announced in 2006, with initial deliveries in 2008. Upgrade packages are available to modernize older PC-12s to glass cockpits as well. Further refinements have been introduced since then, such as LED external lighting -- much more reliable than incandescent bulbs -- new interior packages, an internal wireless communications system, and electrically-actuated landing gear replacing the old hydraulic scheme.

* The PC-12 has been obtained by military and paramilitary services as a utility aircraft. In 1995 Pilatus also announced a "multi-mission" variant of the PC-12 for surveillance, environmental survey, aerial mapping, and so on. This variant was originally named "PC-12 Eagle" but later became known as the "PC-12M". The PC-12M featured an uprated electrical power generation system to support sensor or other payloads, plus a quick-change interior to permit flexible mission support.

The initial PC-12M demonstrator flown in 1995 featured a Raytheon Sea Vue synthetic aperture radar (SAR) in a centerline belly "canoe" fairing with an electro-optic / infrared (EO/IR) turret at the front of the pod, plus a digital datalink system. Two more demonstrators were flown, with one ending up being used by the Swiss for trials. There was little interest in the concept in the 1990s and the PC-12M effort got the axe in 2002.

It was promptly revived in 2003 in a new configuration as the "PC-12 Spectre", which in development features a retractable EO/IR turret under the rear fuselage and twin workstations, plus a digital video recorder and a military communications / datalink system. Of course the Spectre is now being offered with PC-12 NG flight systems; other gear, such as a SAR or defensive countermeasures, can be added at customer request. The Spectre has proven more successful than the Eagle, with ten delivered by 2006; users include Switzerland, Argentina, Bulgaria, and the US Department of Homeland Security (USDHS). The USDHS has at least three, being used for border patrol.

Pilatus PC-12 variants

One prominent user of the PC-12 is the US Air Force Special Operations Command (AFSOC), which obtained at least three dozen of the type from 2005 as the "U-28A". The AFSOC likes it for its capability, performance, and ability to operate from rough fields. Some photos of U-28A machines show them as "slick", close to stock configuration, with no more than an additional antenna or two, presumably for military communications; others have a "farm" of antennas, including one in an expanded fairing at tailplane-tailfin joint, and belly canoes in at least two configurations, one with an imager turret. Given the litter of antennas, U-28As may also carry signals intelligence gear; most or all have defensive countermeasures systems as well.

These aircraft are sometimes painted in civilian-style liveries with subdued national markings, so they can operate in foreign countries without drawing too much attention to themselves. One was lost in a crash in Djibouti in early 2012, with all four aircrew killed, hinting at the US secret war against Islamists in the Horn of Africa. A total of 18 PC-12 / U-28A machines were also ordered by Afghanistan, working with the US military, with the first of these aircraft delivered in late 2013. They are described as having been fitted with a "very basic" surveillance system.

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[3] COMMENTS, SOURCES, & REVISION HISTORY

* A number of other single turboprop executive aircraft have been built, but none have achieved the success of the TBM or PC-12 so far. In the mid-1990s the Myasishchev organization of Russia introduced the "M-101T", a machine with a general configuration along the lines of the TBM, if somewhat boxier in appearance, but only a handful were sold. From 2000, the Czech Aero Vodochody firm also worked on a turboprop single, the "Ae 270 Ibis", that was very much along the lines of the PC-12, but the project was finally canceled in 2008. There's been talk of reviving it, but nobody's holding their breath waiting to see if it will really happen.

One contender still more or less in the running is the "LT" of Epic Air LLC, based in the US state of Oregon -- the LT being sold to particularly ambitious aircraft kitbuilders. The Epic LT performed its initial flight in 2004. It is of the same general configuration as the TBM and PC-12 -- a low-wing monoplane with retractable tricycle landing gear, powered by a single turboprop engine -- but is only available in a luxury passenger configuration, there being no option for a big cargo door; it is also mostly made of carbon composite material, and appropriately has an extremely sleek configuration.

Epic LT

Wingspan of the Epic LT is 13.1 meters (43 feet), length is 11.2 meters (36 feet 10 inches), and empty weight is 2 tonnes (4,400 pounds). Standard powerplant is the PWC PT6A-67 with 895 kW (1,200 SHP) and driving a Hartzell propeller, providing a top cruise speed of 600 KPH (375 MPH / 325 KT). Several users built them as kits, flying them as experimentals, the type not yet having been certified.

Epic has promoted a set of enhanced derivatives, including a higher-end "Dynasty" variant and a twin-turboprop "Twin Dynasty" variant, but they never happened. Epic is a young company trying to become established, and accordingly has outlined futures that weren't so easy to realize, as emphasized by the bankruptcy of the firm in 2009. However, Epic rose from the dead via a buyout and reorganization; whether it gets on a stronger footing remains to be seen.

The Piper "PA-46 Malibu" turboprop executive aircraft also should be mentioned here, but since the family includes piston variants, it needs to be discussed elsewhere. Beechcraft is rumored to be working on a turboprop single, possibly derived from the company's popular Super King Air series, but company officials have been very coy about it, and for the moment it's just a matter of interesting speculation.

* This item was mostly derived from examinations of various editions of JANE'S ALL THE WORLD'S AIRCRAFT, manufacturer websites, and such small commentaries as I could find elsewhere. Finding much detail on the SOCATA TBM was particularly difficult, variant descriptions being a real headache.

* Revision history:

   v1.0.0 / 01 apr 13 / PC-12 originally part of Cessna Caravan document.
   v1.0.1 / 01 apr 14 / Minor tweaks.
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