Auxiliary fuel tanks increase range and new exits boost capacity to 215 seats
Boeing will make some of the key elements of the new 737-900ER standard on other 737 variants following the formal launch of the higher-capacity, extended-range aircraft that was previously dubbed the -900X. The launch of the variant, which Boeing has been proposing to customers for over four years, followed confirmation of a deal for up to 60 aircraft (including 30 options) from Indonesian low-cost carrier Lion Air (Flight International, 19-25 July).
The extended-range version is dimensionally identical to the existing -900, but will feature several structural and configuration changes to increase passenger capacity to 215 in a single-class layout. Key modifications include the addition of a pair of Type II exit doors just aft of the wing, plus provisioning for up to two auxiliary fuel tanks in the cargo hold. The -900ER will also incorporate the recently developed flat aft pressure bulkhead, which is expected to become standard on all new-build 737s after the introduction of the variant on the line from 2006.
The revised bulkhead creates additional internal volume, particularly for a revised aft galley layout, which helps free space for a few additional seats. Provision for the new exits – which boost the exit limit capacity from 189 to 215 passengers – “will be structurally installed as standard in all -900s, and will allow operators to decide if the door should be activated or deactivated”, says 737 chief project engineer Mike Delaney.
The de-activation feature will enhance the re-marketability of the aircraft, says Delaney, adding that when deactivated it will be covered with a standard sidewall and overhead bin interior.
The longer-range variant is also structurally strengthened to increase design weights for the higher fuel loads and will be available with optional maximum take-off weights (MTOW) up to 85,200kg (187,700lb) – 6,100kg greater than the heaviest -900. Maximum zero fuel weight and landing weight options similarly rise to 67,800kg and 71,400kg, respectively. The -900ER is the heaviest variant of the twinjet ever developed and its weight is on a par with initial 727-200 models.
Translated into range and payload, Boeing says the -900ER with the auxiliary tanks will fly up to 5,900km (3,200nm) with 180 passengers, compared to the 5,550km range of an Airbus A321 carrying 185 passengers. Without any auxiliary tanks “the range still exceeds 2,800nm” says Delaney.
The -900ER will also have the soon-to-be flight tested short-field performance wing changes as well as additional leading- and trailing- edge enhancements to maintain current field performance.
The landing gear, wheels and brakes will also be strengthened for the higher weights while a dual position tailskid will protect the aft fuselage from over-rotation.
Long-lead items and detailed parts will be produced this year, with assembly of the first airframe starting in 2006. A five-month flight-test effort involving two aircraft will begin in late 2006 with entry into service with Lion Air expected in the first half of 2007.
GUY NORRIS/LOS ANGELES
Source: Flight International
