RJX tests accelerate as jet No. 2 joins program

 - May 9, 2008, 5:28 AM

BAE Systems Regional Aircraft has completed four months of test flights in its new Avro RJX85, leaving officials “very confident” of meeting, if not exceeding, the 15- to 20-percent-enhanced fuel burn and other performance-improvement targets set for the 80- to 112-seat quad-jet. The Honeywell AS907-powered airplane has completed final tests to clear its full altitude and speed envelope, and has flown at speeds up to Mach 0.80 and 360 kias to demonstrate a margin over flight-manual capabilities, according to the UK manufacturer. The RJX is a variant of the Avro RJ, itself a development of the earlier BAE 146 regional quad-jet.

Test flying with the new production-standard Honeywell engines should increase later this month, when a second aircraft joins the 800-hr program, albeit somewhat later than previously envisioned. Since its maiden flight on April 28, the initial RJX85 development aircraft had accumulated almost 130 hr in some 60 test flights by August 5, when it flew for the first time with a full set of four so-called “Block 2” engines. BAE has scheduled a similarly powered RJX100 to fly in “late September;” the larger aircraft had been due to take to the air before the end of July, but has been awaiting the new powerplants. Honeywell has said that there is no plan for a further enhancement to produce a “Block 3” standard.

A third aircraft, the first “true” production new-build RJX100, will become the first delivered aircraft when it joins British European’s fleet next April. It has been added to the flight-test program as BAE works to overcome the five-month delay caused by a longer-than-expected gestation period for the BAE/Honeywell/GKN “integrated powerplant system”. This machine will carry much less test equipment than the first two aircraft, which are modified first-generation Avro RJs.

Initial development aircraft G-ORJX completed about a month’s flying with one Block 2 engine alongside three earlier Block 1 units, after which BAE said the powerplant had worked well throughout the performance range–“particularly the full-authority digital engine-control [Fadec] system.” Compared with the initial batch of engines fitted to the development aircraft, this Block 2 powerplant meets the “full performance standard,” according to BAE.

Honeywell has made performance-related improvements to engine hardware as well as the Fadec software. This has been aimed primarily at improving durability, as well as modifying thrust characteristics and further reducing fuel burn. BAE said that flight-testing could now address all areas of performance.

Fadec modifications were introduced to optimize fuel flow, which previously had produced a slightly rich mixture that was evident in smoky emissions. Initial testing with the single Block 2 engine had “immediately” demonstrated generally smoother operation, including quicker acceleration, said BAE. Engineers have achieved windmill starts down to 250 kt.

BAE scheduled the first development aircraft to fly to the U.S. for weather trials, including hot-and-high demonstrations and a period in the climatic chamber at Eglin AFB in Florida. The company, however, has no plans to show the aircraft at this month’s NBAA Convention in New Orleans, although BAE officials do plan to attend.

The bulk of flight-test items involve the initial aircraft, including  engine ground and flight starting, systems, handling and operability, and intake distortion; Fadec software development; blowing snow and freezing fog; auxiliary power unit systems and starting; ventilation/bleed air; operational and scheduled performance; flutter testing; aircraft handling; automatic-landing validation; flight-data recorder; simulator data; hot and cold weather and hot-and-high altitude testing; and European Joint Aviation Authorities assessment.

BAE plans to share much of that work with the RJX100 development machine that otherwise has no unique duties. The third aircraft is to be devoted to internal noise measurement, high-intensity radiation-field work, and ozone and carbon dioxide emissions activity, as well as certification assessment.