Learjet 31

The Learjet 31 is an American ten seat (two crew and eight passengers) twin-engined, high speed business jet. Manufactured by Learjet (a subsidiary of Bombardier) as the successor to the Learjet 29.

History

The first flight of the LJ31 took place on 11 May 1987. The Learjet 31A variant was introduced in October 1990. This version featured increased cruising speed, a digital avionics system with EFIS supplied by AlliedSignal (today Honeywell) and an instrument panel layout change. The nose gear wheel is steered by a Steer by Wire system. The windshield could be heated electrically.

The Learjet 31ER with increased range was produced.

The first 31A serial number 31A-035 entered service 15 August 1991. The last 31A delivered, serial number 31A-242 was delivered 1 October 2003.

Variants

Learjet 31

The Learjet Model 31 is, arguably, the ultimate realization of the original Learjet series (dating back to the model 23 of 1963). Essentially combining the fuselage and engines of the model 35/36 with the “Longhorn” wing of the 28, 29 and 55 models, results in performance which is equaled by few aircraft. Normal cruise altitudes range from 41,000 to 47,000 feet (12,500-14,900 m) and the aircraft’s maximum cruise altitude of 51,000 feet (15,500 m) is a distinction shared by only a handful of civil aircraft. Improvements over earlier models, such as “Delta-Fins” and a “Ski-Locker” increased the utility and improved the performance of the model 31. Addition of Delta-Fins at the bottom of the empennage simplified the certification process of the aircraft by eliminating the need for a “stick pusher” stall avoidance device. Increased directional stability, as a result of the Delta-Fins, was also a welcome benefit.

Learjet 31A

The Learjet 31A was announced in 1990 as a replacement after building 38 Learjet 31’s. Note, the last

six 31’s, 31-033, 31-033A, 31-033B, 31-033C, 31-033D, 31-034 were equipped with Honeywell avionics systems for Singapore Airlines flight training and have a unique cockpit. The model 31A boasted numerous modifications, however the most notable changes would take place on the flight deck. Key modifications and updates to the model 31A cockpit and avionics include; a Bendix King (now Honeywell after the merger with Allied Signal) Electronic Flight Information System 50, with Universal 1M, 1B and 1C flight management system, a dual KFC 3100 two-axis autopilot and flight director with yaw damper, and dual Bendix King (Radios sold to Chelton Avionics when Allied Signal combined with Honeywell) VCS-40A com units, VN-411B Series III navigation receivers.

In the year 2000 the Learjet 31A was again revised. Takeoff and landing weights were increased.^[1] The original design N₂ digital electronic engine control (DEEC) was replaced with an N₁ DEEC,^[1][2] and the thrust reversers became standard equipment. The original R12 freon air conditioning system was replaced with an R134A system divided into two zones - cockpit and cabin.^[2]

Learjet 31A/ER

Extended range version of the Learjet 31A, with range of 1911 nm (2199 miles or 3539 km).

After-Market Modifications

Raisbeck Engineering offers two after-market modifications to the Learjet 31 aircraft. The Aft Fuselage Locker offered by this company is an external storage container mounted below the rear fuselage that can hold 300 lb of baggage.^[3] The addition of the locker imposes no performance penalties on the aircraft. This company also offers the ZR LITE performance improvement package.^[4] This modification reduces the cruise drag of the aircraft resulting in 25% less time-to-climb, 3000 to 4000 feet higher initial cruise altitude, .02+ increase in cruise Mach at equal power settings, 1% decrease in N1 and 15° ITT reduction at equal Mach and a 5-11% increase in range.

Operators

 Pakistan

• Government of Balochistan, Pakistan

 United States

• NASA
• Elite Air

Specifications (Learjet 31)

Data from Jane's All The World's Aircraft 1988–89^[5]

General characteristics

• Crew: 2
• Capacity: 8 passengers
• Length: 48 ft 8 in (14.83 m)
• Wingspan: 43 ft 10 in (13.36 m)
• Height: 12 ft 3 in (3.73 m)
• Wing area: 264.5 sq ft (24.57 m²)
• Empty weight: 9,857 lb (4,471 kg)
• Gross weight: 15,500 lb (7,031 kg)
• Powerplant: 2 × Garrett TFE731-2 turbofan, 3,500 lbf (15.6 kN) thrust each

Performance

• Maximum speed: Mach 0.81
• Cruise speed: 515 mph (448 kn; 829 km/h)
• Stall speed: 97 mph (84 kn; 156 km/h)
• Range: 1,877 mi (1,631 nmi; 3,021 km) (Standard fuel, four passengers,)
• Service ceiling: 51,000 ft (15,545 m)
• Rate of climb: 5,480 ft/min (27.8 m/s)

References

Notes

Bibliography

• 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.

External links

Media related to Learjet 31 at Wikimedia Commons

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