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Aviation History
1989
1989 - 2905.PDF
Continued from P 43 towards the engine-mounting bulkhead. A larger inertial separation anti-icing air inlet sits directly beneath the spinner. TBM's performance targets depend heavily on the 39ft 10 Sin-span cantilever wing, the root section of which is based on the Aero spatiale RA 1643 aerofoil. With an area of 193ft2 and a 6-5° dihedral, the wing has a relatively high aspect ratio of 8-22. Lift performance at low speeds is enhanced by large trailing-edge flaps spanning 71 per cent of the wing length. The two-section Nomex- honeycomb flaps are electrically actuated to hinge down, reducing stalling speeds to 61kt to comply with low-speed handling limits set by US FAA Federal Aviation Administration FAR Part 23 (for one- or two-pilot operation), says TBM. The extra-large flaps have reduced the area of trailing edge available for ailerons, and mechanically coupled spoilers have therefore been installed inboard of the ailerons to augment roll control. Full-chord upturned winglets are also planned for production aircraft, to improve lift at the wing tip and reduce drag during the cruise. A 2in-high wing fence has also been added this summer to induce symmetrical stall. CONVENTIONAL ALLOYS Control surfaces are made of bonded composite materials, while nearly all other parts of the airframe are fabricated from conventional aluminium alloys. The main carry-through wing spar is a machined unit with fail-safe attachment points and crack- stopper bands. Design limit load factors are -l-5g to +3-8g at 6,2501b, though ultimate loads are defined as 1 • 5 times the limit load factors. Within the overall limits, maximum operating speed at sea level to 25,200ft is set at 270kt, while maximum operating Mach number at 25,500ft and above is given as Mach 0-65. Other aerodynamic changes to the basic design have included the addition of 6ft 6in-long strakes under the tail to improve lateral stability. The tail area has also been increased by 20 per cent to 27• 54ft2 by pushing the leading edge forward and increasing the fin and dorsal area. No changes have been made to the rudder, which is mechanically controlled through the rudder pedals and incorporates an adjustable rudder tab. Overall height of the refined TBM. 700 Re-engining with the Pratt & Whitney PT6A-64 meant an additional exhaust on the port side also remains unchanged at Oft. • Plans for a movable horizontal stabiliser on production models were dropped in favour of a more conventional solution, so the elevators sport large trim tabs. The tail has a 16ft span, an aspect ratio of 5, and a dihedral of 6-5°. A circular fuselage section, with a maximum internal cabin width of 4ft, incor porates a retractable clam-shell cabin door, 46in high and 25-8in wide. The new door replaces the original single-piece unit. The lower half contains an integral airstair and is held in place by an ingeniously designed hinge. A plug-type emergency exit is posi tioned diagonally opposite on the forward starboard side of the cabin and hinges inwards instead of outwards as originally planned, says TBM. EXTENDED INTERNALLY The cabin length was extended internally to 13ft 5 • 5in by pushing back the position of the aft pressure bulkhead by two fuselage frames. The change was made internally, however, and the TBM.700's overall length remains 34ft 3in. The 230ft3 cabin volume is pressur ised to maintain a differential pressure of 6-21b/in2, for an 8,830ft cabin altitude at 30,000ft, using engine bleed air. Ram air for cabin ventilation can be used when the pres- surisation system is not in use, and sea-level Strakes have been located I , - ;. • , under the tail for longitudinal stability •~-:' w^^Mf^%< cabin altitude can be maintained to 14,430ft. Pressurisation is controlled by two outflow valves located in the aft pressure bulkhead. Two baggage areas abut on to the pressure bulkheads. The smaller (8 • 8ft3) area is located in the nose section of the aircraft between the engine compartment and the flightdeck, while the larger (31 • 8ft3) area lies within the pressurised cabin itself. Total weight capacity for both areas is 1761b. A maximum take-off weight of 6,2501b (including 1101b of optional equipment) is handled by main and nose landing gear using a single wheel, forged aluminium assembly, and an actuating strut. The landing gear is electrically controlled and hydraulically actu ated, and is completely enclosed by gear doors when retracted. The main gear doors retract into the wing and the nose gear retracts rearwards into the lower engine compartment. The landing gear may be extended at speeds of up to 180kt indicated airspeed; a warning horn will sound if the gear is still retracted when landing flap position is selected or when the throttle is set at idle position. The gear can be extended manually using a hydraulic system in emergency. A mechanical locking system ensures all three gear actuators lock in the down position. The nose gear is mechanically steered by rudder pedals to 18° either side of centre, and toe-actuated single disc brakes are installed in the main-gear wheels. Normal aircraft brak ing can be applied from either the pilot's or co-pilot's seat. STANDARD EQUIPMENT Other dual controls are also provided as stan dard equipment and include control wheel columns, adjustable rudder pedals, and power brakes. Pushrod and cable systems, monitored by integrated track and dissymmetry detectors, are used to actuate the'rudder, elevator, and ailerons. Primary pitch, yaw, and roll trim are electrically powered through split switches mounted on the control column. Trim wheels installed on the pedestal are used as a backup in a dual FLIGHT INTERNATIONAL 23 September 1989 47
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