Guy Norris/LOS ANGELES
Design details have been released of a novel overwing emergency exit developed by Boeing for the Next Generation 737 family in efforts to conclude its long-running debate with the European Joint Aviation Authorities (JAA) over exit-limited maximum seating (Flight International, 9-15 July).
"We have now built a production-equivalent mock-up of the door and we've run our tests with it for the FAA [US Federal Aviation Administration] and the JAA to show that it could be opened by somebody off the street within three seconds," says executive vice-president for aircraft development and definition Harry Arnold. "The tests were successful and we're now in the process of getting formal paperwork from the FAA on granting certification. The JAA has gone out for public comment on their proposed certification of the door and aircraft at 149 passengers for the 737-600/700 and 189 for the -800," he adds.
Boeing hopes that the JAA comment period, which expired on 11 July, will lead to European certification of the new door and the associated higher seating capacities in time for the first deliveries, to Maersk of Denmark, in October. "We will also be retrofitting some aircraft already built for Maersk and Germania," says Arnold, who adds that the new design will be standard from aircraft 26 onwards.
The revision is crucial to European charter operators, which want to use the full 189-seat capacity of the stretched -800 and the 149 of the -600/700. The JAA says that it would only consider approving these limits "-if we could come up with an innovative change to the aircraft that would improve the exit capability", says Arnold.
Boeing is "optimistic" that it will obtain JAA approval, says Arnold. The company stresses that the current Type III exits meet existing regulations, but that, to add the additional seating, the JAA required "-us to 'push the state of the art', which is what we've done".
The new automatic overwing exit door combines the standard "plug"-type door features of the current design, with the new capability of opening a completely clear exit. The door is hinged along the upper edge and moves inwards at the top when the emergency-exit handle is pulled. The handle is linked to a cam arrangement which begins the opening sequence, which rotates the door inwards to clear the plug stops. The door then moves down to clear the lower plug stops before rotating on springs out and up. The simple handle mechanism can be activated from seat rows forward and aft of the exit row as well as from the middle and window seat of the exit row itself.
"It is still a plug door, so it is not dependent on locks and latches to keep it pressurised," says Arnold. The concept is also being studied for the 757 family.