Learjet 75

By Fred George fred_george@aviationweek.com
Source: Business & Commercial Aviation
December 01, 2013
Credit: Bombardier

There's a long tradition of over-promising and under-delivering in business aviation, but it's still a surefire way to disappoint customers and sour an aircraft's reputation. The Learjet 45, as an example, promised more than it could ever deliver, according to some longtime Learjet operators. The Learjet 75, the latest derivative of the Model 45, reverses most of those past shortcomings and delivers new levels of performance, cabin comfort and cockpit capabilities.

The Learjet 45 fell short of expectations because it gained empty weight during development and there was virtually no allowance for optional, but almost essential, equipment. Bombardier wanted to keep the spec BOW at 12,100 lb. and the base price below $6 million, so FMS, GPS, TCAS, GPWS and ELT all were options. Also left out were typical upgrades such as IFE, air-to-ground phone and APU. The installed weight of the APU alone is about 210 lb. As a result, the heft of the average Learjet 45 grew to be a ton, or more, above Bombardier's advertised spec weight.

A series of post-certification weight increases improved the aircraft's tanks-full payload but sapped its takeoff performance. Being so bloated, takeoff field length ballooned from 4,200 ft. to 5,040 ft.

The Learjet 75 has sportier perform–ance, mainly due to a 10% throttle push that bumps up engine thrust from 3,500 lb. to 3,850 lb. Most valuable to operators, TOFL is reduced by as much as 12%. The new aircraft gets new canted winglets that effectively increase span by 3 ft., thereby decreasing wing loading, which also improves takeoff performance. Their blended radii also reduce transonic drag for more efficient high-speed cruise.

Garmin G5000 flat-panel avionics replace the Honeywell Primus 1000 gear, adding new capabilities and shrinking empty weight by 200 lb. Almost all that weight comes out of the nose, so c.g. shifts aft, resulting in less trim drag, further improving cruise efficiency.

The 200-lb. avionics weight loss also enables Learjet 75 operators to fill the tanks and fill the seats, as promised by the original Model 45. And the combination of the new winglets and reduction in trim drag also boosts range by 4%.

Unlike the original Model 45, the Learjet 75 comes loaded with a full complement of standard equipment, including dual FMS with WAAS, TCAS II, SVS and electronic charts. The Honeywell RE100 APU remains standard equipment, as it was aboard the 45XR. It's almost essential for ground ops, because prior to engine start, it produces the bleed air needed for the air-cycle machine to warm and cool the cockpit and cabin. You can't plug in a GPU and heat or cool the airplane.


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