The Learjet 45 (LJ45) is a mid-size business jet aircraft produced by the Learjet Division of Bombardier Aerospace.
The Model 45 was the first all-new design since the original Learjet, and significantly altered the Learjet line. Through its four primary variants – the original Model 45, the Model 45XR, Model 40 and Model 40XR – it was the Learjet Division's principal product from the 1990s until the introduction of the Model 75 variant in 2012.
The Model 45 was developed in the 1990s as a competitor in the "super-light" business jet category, a rival to the popular Cessna Citation Excel / XLS – but sacrificing the Cessna's stand-up room for the Learjet family's traditional high-speed performance.
The Model 45 was Learjet's first completely new ("clean sheet") design since the company's first aircraft (all other models having been evolved from the original 1963 Learjet design, the Model 23). The Model 45 was developed to make Learjets fundamentally more competitive against newer designs from competing manufacturers. But, as a clean-sheet design (starting from scratch), being built to more rigorous (FAR Part 25) rules than previous Learjets, the aircraft's development took substantially longer than that of previous Learjet models.
The development of the LJ45 began in 1989, but was not announced by Bombardier until September, 1992. First flight of the prototype aircraft took place on October 7, 1995 – the 32nd anniversary of the first flight of the original Learjet 23. FAA certification was delayed, and finally granted in September 1997, with the first customer aircraft subsequently delivered in mid-1998. The aviation magazine Flying reported that the Lear 45 was first certified under FAR Part 25 (transport category rules) in 1998.
Initially, delays in production resulted in frustrated customers and lost or delayed revenues. Some customers' orders were delayed more than two years.
By late 2006, Learjet had delivered over 300 Model 45s (40 of which were its improved version, the Model 45XR). By November 2010, over 500 of the Model 45 and 45XR had been delivered.
Initially, numerous mechanical and electrical problems began appearing in the aircraft after delivery – including cracked windshields, problems with pressurization, fried power distribution panels, and inappropriate alarms. These and other problems commonly forced Model 45 operators to ground their aircraft about once a month, limiting their use.
Problems came to a head in August 2003, when the FAA discovered a defective fastener for the Model 45's horizontal stabilizer could break, sending the airplane into a fatal dive. The FAA grounded all Learjet 45s, across the nation, and they all sat on the ground for a month, while the manufacturer struggled to develop a fix and get it to aircraft in the field.
By 2007, Model 45 operators were said to have a "love-hate" relationship with the aircraft – appreciating its exceptional combination of performance, payload and economics, but frustrated by frequent maintenance problems, often grounding the aircraft, and difficulty getting prompt and adequate product support and parts. However, 10 years later, a 2017 "Used Aircraft Report" by Business & Commercial Aviation magazine indicated that owners now regard the aircraft as "gas-and-go airplane" and credit it "with great reliability," and the article's author, B/CA senior editor Fred George, describes it as "a rock-solid reliable workhorse."
By 2018, Learjet 45/45XRs were priced at $1.5–4.9 million.
In size, the LJ45 and LJ45XR fit between the smaller Learjet 31 and Learjet 40, at the low end, and the larger Learjet 60 at the top of the Learjet product line. It offers the operating economics typical of a "light" business jet, but the performance and comfort of a "mid-size" business jet.
It has a 1,971-nautical-mile (3,650 km; 2,268 mi) range at Mach 0.81 with four passengers on board.
The plane was designed around a flat-floor cabin, with a non-circular cross-section for additional headroom. Typical interior configuration is eight passenger seats, in a double-club seating arrangement, and a fully enclosed toilet (usable as a 9th seat) and an adjoining 15-cubic-foot baggage area. An external 50-cubic-foot baggage area is also provided.
The Model 45 was Learjet's first "clean-sheet" (all-new) design since the development of the original Model 23. (All previous models had been derivatives of the Model 23, with the wide-fuselage Model 55 and Model 60 utilizing the basic wing design originating in the Model 23, but with extensions and winglets; some, however, view the Model 55 as a "clean sheet" design, also.)
Previous Learjet designs had used rigorous, extensive "fail-safe" structures in the wing and tail assemblies, with numerous wing spars providing a highly reinforced structure (derived from the Swiss-designed P-16 prototype fighter that was the original basis for the first Learjet) – but the Model 45, instead, used a lighter, less-robust structure, affording less cost in manufacture and lower aircraft empty weights, resulting in improved capacity, efficiency and some performance enhancement (for a given amount of engine power), at a competitive price.
Outwardly, however, the Model 45 retained the traditional Learjet appearance, with its semi-swept wing, T-tail, sharp nose, and wrap-around windshield – while using engines and avionics similar to those in the Model 60.
It also incorporated two conspicuous modifications pioneered on earlier Learjets: the "delta fins" (twin ventral fins, positioned to help stabilize the aircraft in flight, and help right the aircraft in a deep aerodynamic stall) – and winglets (upturned wingtips to reduce induced drag and improve stability). Among other characteristics, the design has reportedly yielded the most benign stall characteristics of any "light" business jet to date (as of 2017).