Falcon 900DX takes 900C to the next level

Aviation International News » July 2004
April 2, 2007, 7:57 AM

In late May at the EBACE show in Geneva, Dassault unveiled a new version of the Falcon 900. Dubbed the Falcon 900DX, the trijet is a clone of the 900EX, except for its fuel tanks. Dassault salespeople, however, can arguably talk about value for money–the 900DX’s price is hardly higher than that of the 900C it replaces ($31.95 million versus $31.6 million). Yet the 4,100-nm Falcon 900DX will benefit from all the technological advances introduced on the 4,500-nm 900EX, including more efficient engines and the EASy flight deck.

The French manufacturer is claiming a 5-percent reduction in operating costs. Asked how Dassault will achieve this, a spokesman told AIN that the extra efficiency will come mainly from the engines.

The 5,000-pound-thrust Honeywell TFE731-60 turbofans are less thirsty than the 4,750-pound-thrust TFE731-5BR-1Cs found on the 900C.

According to Honeywell, the TFE731-60 delivers 1,120 pounds of cruise thrust at 40,000 feet and Mach 0.80. Cruise fuel consumption is 12 percent less than that of the 900C thanks to a wide-chord, damperless fan that provides 17 percent more flow capacity.

Dassault is claiming the 900DX “uses 40 percent less fuel than its nearest competitor”–that airplane being, in Dassault’s view, the 4,350-nm Gulfstream 450. The spokesman noted that the comparison had been made based on a 3,000-nm trip, using performance-manual data.

Asked to comment on the comparison, a Gulfstream spokesman said, “Dassault’s fuel-burn claim is exaggerated,” he told AIN. For a typical 1,000-nm mission, he said, the fuel burn of the Falcon 900DX is estimated to be only about 27 percent better than the G450’s. “However, because of higher maintenance costs with the Falcon 900DX, overall direct operating cost is the same as the G450’s–about $1,750 per hour,” he concluded.

Nevertheless, Dassault said lower maintenance costs for the engines should also drive down operating costs. Maintenance service plans (MSPs) offered by the engine maker should result in lower and more predictable costs for the customer. Moreover, the time between overhauls should increase, Dassault said. For example, Honeywell said that single-crystal blade material in the high-pressure and first-stage low-pressure turbines will enhance hot-section durability. Vane- and blade-cooling effectiveness has been improved as well.

The TFE731-60, which is more modern than the -5BR-1C, is equipped with single-channel digital engine control and hydromechanical backup. The digital engine control incorporates engine synchronization, automatic power reserve functions and fully automatic starting. It also yields precise automatic power management, Honeywell claimed. Last, but not least, it provides engine condition trend monitoring, a tool that benefits maintenance costs.

More efficient engines translate into lower operating costs and more range. Nonstop flights between city pairs such as Geneva and Detroit, New York and Athens and Chicago and Rome are now possible. The maximum range of 4,100 nm with eight passengers, no wind and NBAA IFR reserves requires the maximum fuel load of 18,830 pounds.

The Falcon 900C, under the same conditions, was able to fly only 3,920 nm and still consumed its maximum fuel load of 19,165 pounds. Nevertheless, Dassault previously advertised a 4,000-nm range with five passengers for the 900C.

The higher-thrust engines will also yield better climb performance. Dassault’s new Falcon will be able to reach 39,000 feet in 18 minutes, compared with 23 minutes for the 900C. In addition, the TFE731-60 will give the 900DX better takeoff performance: balanced field length at mtow is 4,890 feet, versus 4,935 feet for the 900C.

More significant is enhanced hot-and-high performance. The aforementioned balanced field lengths are computed at ISA+17 for the new trijet and only ISA+10 for its predecessor. This translates into more range. From Aspen, Colo., on a hot day (77 degrees F), the range increases from 2,785- to 3,560 nm.

Other new systems on the Falcon 900DX are those that were introduced on the Falcon 900EX when it was fitted with the EASy flight deck. For example, cabin-pressure control laws are more advanced in the new Liebherr pressurization system. The new Falcon 900s also get a brake-by-wire system, but with hydraulic actuators, from ABSC. Intertechnique provides new fuel-metering and oxygen systems.

The Falcon 900DX retains the cabin of the 900 series–length, 33 feet 2 inches; maximum width, 92 inches; and height, 74 inches. Since the new engines are quieter, passengers should benefit from “a couple of decibels under the noise level found in the 900C’s cabin,” the Dassault spokesman said. However, he emphasized that this has yet to be confirmed by flight tests.

The customer is not the only beneficiary in the 900DX program. Dassault will cut production costs by using more components common to the Falcon family. In fact, the French manufacturer will be using the same flight deck, engines and systems throughout the 900 series. Moreover, the T12 section, which includes the nose, cockpit and forward fuselage sections, is the same as that of the Falcon 2000.

Common parts, tooling and production procedures rationalize the processes. Finally, additional fuel tanks and related fuel circuitry on the 900EX are “essentially the only differences with the 900DX,” the Dassault spokesman told AIN. Dassault anticipates that ground tests of the 900DX will start in February or March, with flight tests following next June. The manufacturer expects to receive FAA and EASA (European Aviation Safety Agency) certification during the third quarter of next year, with first deliveries following in the fourth quarter.   

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