Guy Norris/LOS ANGELES
THE McDONNELL Douglas (MDC) MD-90 was certificated by the European Joint Aviation Authorities (JAA) on 16 October, as Scandinavian carrier SAS took delivery of its first aircraft.
Type certification was formally presented by the JAA to MDC just before the SAS delivery ceremony. The event marks the end of a three-year-long struggle for MDC, which, at one point in 1995, considered abandoning JAA certification altogether until complete harmonisation was accomplished with the US Federal Aviation Administration.
In all, some 31 changes have been made to comply with JAA requirements. Among the most significant is the addition of a stick-pusher, which was not required by the FAA. The MD-90, like the MD-80, has a stick-shaker, to warn the crew of a stall, and a supplementary stall-recognition system (SSRS), which alerts the crew with flashing lights and aural warnings. "The stick pusher now comes in first after the SSRS and works on the same schedule," says MD-90 deputy chief designer, Tony Parker. "SAS flew it and found it acceptable," he adds.
The aircraft's Mmo (maximum operating Mach number) has been reduced to 0.825 from the Mach 0.84 cleared by the FAA. The lower Mmo opens up a larger gap between the buffet boundary and highest permitted operating speeds and is required for "structural reasons", says Parker, who adds that no operators are likely to be affected.
The skin and structure around the nose and tail was also beefed up to withstand a 1.5kg birdstrike. "The FAA accepted this on the basis that it was a derivative," says Parker, who adds that the higher-impact resistance has now been "-cut in as a baseline change" to all MD-90s.
Because of the JAA's stance on cabin evacuation, the maximum permitted number of passengers has been reduced by five, to 167, for European-registered aircraft.
Other changes include a revised design to improve the reliability of the automatic landing-light retraction system, which stows the lights back into the wing in the event of an engine failure on approach or during take-off.
SAS, which has eight MD-90s on firm order and options on a further six, will operate the first aircraft from Oslo, Norway, to Stockholm, Sweden, on 11 November. Pilot training will be conducted during shuttle flights between the three SAS capitals before the first flight from Scandinavia is made to London on 9 December.
All eight aircraft will be in service by 20 January, 1997, when they will be operated to Frankfurt, London and Paris.
Source: Flight International
