Honeywell's AS900 Debuts on Regional and on Business Aircraft

Honeywell's AS900 turbofan is accumulating hours rapidly, as flight testing of Bombardier's Continental Jet and BAE System's RJX ramps up in anticipation of 2002 type certification for both of the aircraft.

The 6,672-pounds-thrust (to ISA + 15°C) AS907 took to the air for the first time August 14 aboard the Continental Jet at Bombardier's Wichita flight test facility.

No problems were reported with the new engines during the maiden flight. The eight-passenger CJ is designed to fly 3,100 nmi at Mach 0.82 at 45,000 feet. A second prototype was expected to join the flight-test program this month.

Meanwhile, in England, the 70-115-passenger RJX regional jetliner-latest incarnation of the now-venerable BAe 146, conceived back in the days when the "e" in the British Aerospace trade mark was lower case-continues to build time on the AS977 variant of the engine, rated at 7,000-pounds-thrust. When developing a new powerplant, it helps to have a four-engine application, in this case, the RJX and its quartet of underwing-mounted turbofans. In seventy flights since April 28, when it ventured aloft for the first time, the RJX prototype logged 550 hours of engine time, as of August 20.

Thirteen AS900 engines are engaged in the development program, addressing certification, endurance, and durability. Accelerated mission testing (AMT) is an essential part of this effort, performed in test cells at Phoenix-based Honeywell Engines and its partners AIDC in Taiwan, Orenda in Canada, and TechSpace Aero in Belgium.

As of late August, 9,500 hours total test time and about 8,500 AFT cycles had been accumulated in the program. According to Honeywell's Victor Valente, director, business development, commercial propulsion, the program's goal is to achieve 10,000 hours of operating time on the AS900 prior to service entry, which is second quarter 2002 for the RJX and sometime in the second half of that year for the Continental Jet.

"We will be able to deliver a fully tested engine, backed by a lot of reliability testing," Valente told Show News. "It is frequently the accessories that give you a lot of trouble on a new engine, so we've included accessory testing as part of the basic engine test program."

Valente said that testing early engine prototypes had revealed some deficiencies in secondary airflow and bearing mount stiffness, requiring subtle refinement of the gas path and reinforcement of shaft bearing mounts.

But the "good news" in the AS900 program, Valente claimed, is that Honeywell engineers met desired performance and temperature margins very early in the program, "so we didn't have to scramble later to get them. Having achieved that, we could then focus on endurance and durability issues. It was a testament to the soundness of our analytical tools and modeling techniques."

The testing program also involved more than 500 hours of flight time aboard Honeywell Engines' Boeing 720 flying testbed, focusing on AS900 performance and operability through the full power range. Further flight work aboard the instrumented B720 will continue this fall in Phoenix with evaluation of both RJX and Continental Jet nacelle systems.

"We are looking at substantially longer TBOs, as well as certifying engines right off the bat for on-condition maintenance," Valente said. "For fixed-interval programs [used predominately by corporate flight departments], we'll certify the AS907 for 3,000 hours between major periodic inspections [MPIs, Honeywell's equivalent of the typical hot-section inspection] and 6,000 hours between compressor zone inspections [CZIs, or complete overhaul]." At maturity, this is expected to rise to, respectively, 3,500 hours and 7,000 hours.