A CRISIS IS EMERGING over the certification of derivative airliners in Europe as the Joint Aviation Authorities (JAA) declines to grant "grandfather rights" for key airworthiness requirements.

McDonnell Douglas (MDC) MD-90s and Boeing's new 737 family are the primary aircraft affected by rules introduced since their forerunners gained approval.

Although the JAA accepts the types' derivative status, specific new regulations threaten to wreck their operating economics and affect sales.

Issues affecting the MD-90 include stall identification and recovery (Flight International, 15-21 February) as well as cabin design and bird-strike resistance.

The new 737 family, spear-headed by the 737-300-sized 737-700, is hit by cabin rules related to evacuation, which would cut its seating capacity, as well as by the "direct-vision" regulations, specifying the area of unobstructed vision in the cabin and the requirement for 16g dynamic-load seats, which Boeing says are not yet available.

Boeing declines to comment directly on the issue, but company sources say: "All we're striving for, and what we hope to see from harmonisation [between the JAA and US Federal Aviation Administration certification requirements] is reasonableness."

A senior 737 project engineer indicates that the company regards a reduction of the -700's capacity in its ferociously competitive market as unthinkable.

MDC is sending design and technology vice-president Allen Haggerty to Europe in mid-April in an effort to convince the JAA that the changes are a waste of time and money. If the JAA maintains its stance, MDC is believed to be considering abandoning European MD-90 certification altogether until complete harmonisation is accomplished.

MDC stresses that the certification issue is "...not a MD-90 problem, it's an industry problem". A company source adds, "The point is, that we thought that the entire certification basis of the aircraft, had been agreed with the JAA."

The JAA requirements include changes to the stall-recognition and recovery system, necessitating installation of a stick-pusher; new bird-strike tests of the tail at speeds in excess of maximum operating speed; and re-certification of the cabin evacuation.

It continues: "This would allow manufacturers to develop derivative aircraft or make major changes to existing ones, with an understanding of our requirements. This would help us in providing cost-effective and well-priced products to the industry."

JAA MD-90 project-certification manager Jo Koerner says: "It is not just tied to the MD-90. It is a fundamental problem as to how the JAA should deal with these derivative aircraft which were born 30 years ago. Right now there are many different opinions around."

Koerner says that with respect to the most pressing MD-90 issue - the acceptance of the supplementary stall-recognition system -his working group is split and proposes to send two pilots to try out the system in the air. They would judge whether, as UK officials propose, a stick-pusher should be required.

He explains: "There are two points of view. One is that we have made up our minds already and we should say so now. The other is that I have a little bit of difficulty basing an important decision on a fundamental disagreement between the [JAA] team and the manufacturer on paperwork discussions only.

"I would like to have a flight-test crew fly it and then come to a decision and that would be the team decision." Koerner has an UK Civil Aviation Authority pilot and a German LBA pilot on his team and would like both to fly the type.

The proposal has been put informally to MDC, but Koerner says that the manufacturer has yet to respond.

Source: Flight International