On 19 April Boeing's 777 became the first of the US manufacturer's commercial airliners to receive simultaneous type/design and production certification from both the US and European airworthiness authorities.
The certification ceremony at Seattle, Washington marks the first milestone in Boeing's co-operative and concurrent certification (CCC) programme begun in 1991. The company believes that the 777 experience establishes a new blueprint for developing future aircraft, which involves both customers and international airworthiness authorities from the outset.
Airbus has pioneered simultaneous approval, winning joint US Federal Aviation Administration and European Joint Aviation Authorities (JAA) certification for the A330 in October 1993.
The 777 certification effort, is likely to notch up around 3,300h, before initial deliveries to United Airlines of the Pratt & Whitney PW4084-powered version, begin on 15 May. This compares with 1,800h amassed by the Boeing 767 at the same stage. Seven aircraft, five PW4084-powered and two fitted with General Electric GE90s, have together built up more than 1,600 flight cycles since flight testing began in June 1994.
The total certification effort to March 1996, with the planned completion of the Rolls Royce Trent-powered 777, will finally involve nine aircraft. Total estimated flight hours by the end of the programme, will be 6,700 over more than 4,800 cycles.
Boeing says that it still plans to have clearance for early extended-range twin-engine operations (ETOPS) in place before the first official delivery to United. "We're reasonably optimistic," says Boeing flight-test director Ken Higgins. "It depends on how the weather goes, and whether we get the right temperatures for take-off at different conditions," he adds.
The company admits that it started a little later than expected, but is now getting more flying hours than originally expected. Pt & W says that its contribution to early ETOPS is well under way. Flight- and ground-test hours for the engine, including ETOPS tests, amount to 21,000 cycles and almost 9,000h.
Following initial type-certification, Boeing is beginning tests of two new systems on the aircraft; a thrust-asymmetry compensation (TAC) system and an electronic checklist. "Both features are already in the simulation and engineering hardware and are working very well" says, 777 division chief test pilot John Cashman.
The TAC senses engine performance through the full-authority digital engine-control and in the event of a power loss on one engine, passes compensatory flight-control inputs to the three primary-flight-control computers in the fly-by-wire flight control system.
Source: Flight International
