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Piper PA-42 Cheyenne
	Cheyenne 400LS
Role	Turboprop
Manufacturer	Piper Aircraft
First flight	May 18, 1979
Number built	192; 149 IIIAs and 43 400s

The Piper PA-42 Cheyenne is a turboprop aircraft built by Piper Aircraft. Aimed directly at Beech's successful King Air twin turboprop series, the PA-42 Cheyennes are larger developments of the earlier PA-31T Cheyennes I and II (in turn themselves turboprop developments of the PA-31 Navajo).

[edit] History

The Piper Cheyenne prototype first flew in 1969. Designated the PA-31T-620, it was essentially a turboprop evolution of the Piper PA-31 Navajo, powered by two Pratt & Whitney Canada PT6A-28 turboprops rated at 620 hp (460 kW) each. Certification was granted on 3 May 1972. The original Cheyenne, produced from 1974 to 1977, did not carry a Roman numeral suffix designation. Because of difficulties complying with certification standards for longitudinal stability, the Cheyenne and later Cheyenne II are equipped with a Stability Augmentation System (SAS), consisting of a stick-pusher system (actuated by an angle-of-attack sensor) designed to provide the pilot with the appropriate stick force gradient - and to keep the airplane at its trim airspeed when flying near aft center of gravity loadings, high power settings, low airspeeds and high angles of attack. Without the SAS, the aircraft demonstrated neutral static stability in its flight regime. Later in 1978 it was re-designated as the Cheyenne II (PA-31T-2-620), due to the production of the PA-31T-1-500.

In 1978 the Cheyenne I (PA-31T-1-500) was introduced. Powered by two 500 shp (370 kW) Pratt and Whitney PT6A-11 engines, the Cheyenne I was marketed as a low-cost step-up turboprop for Piper loyalists. Due to its reduced power, this airplane does not require a SAS. The Cheyenne IIXL (PA-31T-2-620XL) is a stretched (by two feet) version of the Cheyenne II. Certified February 1981 and built until 1984, it does not use SAS.

The Cheyenne IA (PA-31T-1A-500) certified May 1983 and produced until 1985, brought together several design improvements to the basic Cheyenne I. Redesigned cowling allow more air to flow into the engine; situating the propeller closer to the engine air scoop allows greater recovery of high-velocity ram air. New, streamlined exhaust stubs yield more jet thrust than previous models and kept nacelles soot accumulations to a minimum. Together, these changes allow higher inter turbine temperature (ITT) limits. Other improvements to the standard airplane airframe included an auto-ignition system, automatic starter disengage for simplified starting procedures and a larger windshield.

The PA-42-720 Cheyenne III was announced in September 1977. The first production Cheyenne III flew for the first time on May 18, 1979 and FAA certification was granted in early 1980. Compared with the Cheyenne II the PA-42-720 was about 1 m (3 ft) longer, was powered by 537 kW (720-shp) PT6A-41 turboshafts and introduced a T-tail, the most obvious external difference between the PA-31T and PA-42, as well as the most significant change to the series. Deliveries of production Cheyenne IIIs began on June 30, 1980. The standard Cheyenne III has a full complement of deicing equipment, Q-tip propellers, more powerful 250-ampere/hour starter-generators and a 6.3-psi pressurization system backed up by an emergency system operated by the right engine's bleed air.

Also, several key upgrades found available for the Cheyenne IA became standard for the III. These included the SAS, redesigned exhaust stubs, which, according to piper, allowed an extra 6 knots (11 km/h) IAS; and a redesigned engine intake air scoop, which allowed for a larger volume of air to enter the engine. In addition, an external air scoop for oil cooling was available instead of using engine intake air.

The IIIA superseded the Cheyenne III after 88 of the latter aircraft had been delivered. The IIIA is similar in appearance to the III but has PT6A-61 engines and 300 ampere starter-generators. The PT6A-61 engine delivers the same 720 horsepower (540 kW) but, with an additional axial compressor, carries that horsepower to a higher altitude. The IIIA also features an improved air conditioning system, speed stacks, increased passenger head-room, and more reliable fuel control units. The IIIA's ordered by Lufthansa feature flight decks configured to resemble that airline's Airbus A310. Alitalia also uses the IIIA for training purposes.

The higher powered and significantly faster PA-42-1000 is basically a PA-42-720 with far more powerful 1650 shp (de-rate to 1000 shp) Garrett TPE331 turboprops driving four blade, 106-inch diameter, composite-construction Dowty Rotol propellers. The Cheyenne 400LS originally designated the IV, is the hot-rod of the line. In production from 1984 to 1993, it was designated to compete with the performance of smaller fanjets.

Cheyenne PA 42 1000 max S/L speed (cruise) 335 knots, four blade prop, or with new 5 blade German MT prop nearer to 340 knots

[edit] Variants

Piper PA-42-720 Cheyenne III

Cheyenne III, model PA-42-720, equipped with Pratt & Whitney Canada PT6A-41 engines
Cheyenne IIIA, model PA-42-720, equipped with PT6A-61 engines
Cheyenne IV, model PA-42-1000, later the Cheyenne 400LS, and then Cheyenne 400. This is the largest aircraft ever made by Piper, with only 45 built. Powered by 1,000 shp (750 kW) Garrett TPE-331 engines, and 4 bladed props.^[1]

[edit] Specifications (PA-42-720 Cheyenne IIIA)

Data from Jane's All The World's Aircraft 1988-89 ^[2]

General characteristics

Crew: One or two
Capacity: 6 to 9 passengers
Length: 43 ft 4¾ in (13.23 m)
Wingspan: 47 ft 8 in (14.53 m)
Height: 14 ft 9 in (4.50 m)
Wing area: 293.0 ft² (27.22 m²)
Empty weight: 6,837 lb (3,101 kg)
Max takeoff weight: 11,200 lb (5,080 kg)
Powerplant: 2× Pratt & Whitney Canada PT6A-41 turboprop, 720 shp (537 kW) each

Performance

Maximum speed: 314 knots (582 km/h, 362 mph)
Cruise speed: 282 knots (523 km/h, 325 mph) at 35,000 ft (10,700 m)
Stall speed: 89 knots (165 km/5, 103 mph) (flaps and undercarriage down)
Range: 2,270 nmi (4,207 km, 2,614 mi)
Service ceiling: 35,840 ft (10,925 m)
Rate of climb: 2,380 ft/min (12.1 m/s)
Wing loading: 38.2 lb/ft² (186.7 kg/m²)
Power/mass: 0.13 hp/lb (0.21 kW/kg)

[edit] References

^ The Piper PA-42 Cheyenne III/400 history at Airliners.net
^ Taylor 1988, pp. 455–456.

AOPA Pilot, June 1987. Page 38 & 39
Taylor, John W.R. Jane's All The World's Aircraft 1988-89. Coulsdon, UK: Jane's Defence Data, 1988. ISBN 0 7106-0867-5.

[edit] External links

[alnet-0] The Piper PA-42 Cheyenne III/400 history at Airliners.net

[Janes_88_p455-6-1] Taylor 1988, pp. 455–456.

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Contents

[edit] History

[edit] Variants

[edit] Specifications (PA-42-720 Cheyenne IIIA)

[edit] References

[edit] External links