AS900 on Track to Certification

Claiming its AS900 turbofan has proceeded through development relatively trouble-free, Honeywell Engines & Systems is on track to certify the 7,000 pounds thrust-class engine on schedule early next spring.

The ambitious 32-month program is complicated by the fact that two versions of the engine are being developed simultaneously: the AS907 for launch customer Bombardier Aerospace's super midsize Continental bizjet and the AS977 for BAE Systems' RJX regional airliner. The AS907 will be rated at 6,672 pounds thrust, the AS977 at an even 7,000 pounds, both carrying their rated power to ISA+15C.

"It's a very dynamic program with a lot of concurrent activity," AS900 program manager Kurt Noe told Show News. "We are building engines for both the development program and customer consignment and running development tests concurrently with certification tests." Overall, the program is "very healthy," Noe claimed, "meaning we're seeing only minor teething problems in development that are easily addressed without delaying our targeted certification. We are adhering to an aggressive schedule."

Noe credited "lessons learned from previous programs," considerable up-front planning, and modern design tools like CATIA software for the AS900's so-far unhindered development experience. This, plus so-called 'Six-Sigma' concurrent engineering practices, have shaved nearly a year from the engine's development and certification program.

The program has been going so well Honeywell is "already into lead time" for the first AS900 production engines, which will be shipped in March, 32 months after program launch in September 1998. The first complete AS900 was bench-tested in June 1999 and flew for the first time in January 2000 aboard Honeywell's Boeing 720 testbed. As the NBAA Convention opened, about 200 flight hours had been logged, along with 2,800 hours of ground running. By service entry in first quarter 2001, 11,000 total test hours should have been accrued.

Meanwhile, accelerated mission testing (AMT, or cyclic testing) is underway at Honeywell's partner facilities at Aerospace Industries Development Corporation (AIDC) in Taiwan, which is responsible for the AS900's fan module, and Techspace Aero in Belgium, where the engine's low-pressure turbine is under development. AMT involves running the engine at higher-than-normal temperatures and speeds, equating each accelerated cycle to several normal cycles (a ratio of about 4:1), thereby allowing the manufacturer to model a greater number of cycles early in the program to validate the engine's reliability. By certification, AIDC and Techspace are slated to have completed 10,000 mission cycles on their respective engine modules.

Currently, 12 engines are running in the development and certification program at Honeywell's Phoenix, AZ headquarters. About one engine a week will be added to the certification effort through the end of the year, "a schedule that approaches mature production numbers," Noe said. A flight-rated AS977 engine will fly aboard the RJX prototype at the end of this year, followed by a certified example of the AS907 on the Continental prototype next spring.

In the test cell, Honeywell has demonstrated sustained thrust outputs of more than 8,000 pounds from AS907/977 development engines, excess capacity that Noe said would be converted to temperature margin (at the production engines' installed thrust) for extended engine life. "Since takeoff thrust has exceeded our performance guarantee, we are assured the engine will run nice and cool (at rated thrust)," Noe said. Other performance guarantees, such as specific fuel consumption, could also be exceeded by the time the engine receives type approval. (Takeoff TSFC is listed as 0.65 pounds of fuel per pound of thrust per hour.)

Honeywell also received encouraging results in a fan 'blade-out' test conducted earlier this year. This was a developmental test only; the manufacturer will have to do it all over again in February for certification authorities. Meanwhile, hail ingestion, ice slabs and birdstrike tests are scheduled for completion in December.

Honeywell is contracted to provide its AS907 and AS977 engines to Bombardier and BAE as fully dressed bolt-on 'power packages,' complete with nacelles, and in the case of the AS907, thrust reversers. Nacelles for both the Continental and RJX will be supplied by GKN Westland in the UK, and the CJ's reverser by Hurel-Dubois of France.

By David Esler