Commercial applications also beckon for aircraft being defined for US Navy's multi-mission maritime role
Boeing is studying a heavier, longer -range variant of the 737-800 that could be launched on the back of commercial and military market interest, for initial delivery in 2007.
Dubbed the 737-800ERX, the aircraft is being defined for use in the US Navy's multi-mission maritime aircraft (MMA) role for which Boeing is in the final stages of competing against Lockheed Martin (Flight International 24 February-1 March). Retaining the same fuselage length as the standard -800, the -ERX variant includes the heavier-gauge wing for the proposed -900X, a higher-capacity, higher-gross-weight variant of the -900 on offer to charter operators.
"It would also have the -900X landing gear, and Section 44 [wingbody join section] and 'beefed up' nose gear," says 737 Next Generation chief project engineer Mike Delaney, who adds the -800ERX will also include "some parts of the BBJ1 [Boeing Business Jet]". The aircraft will also have unique -800ERX features, particularly around the empennage, which will require strengthening to accommodate related higher structural load requirements of up to 11,400kg (25,000lb).
The heavier -ERX will have an increased maximum take-off weight of 83,500kg, 4,540kg more than the standard high-gross-weight option -800. The strengthened wing of the -900X is appropriately sized as the planned weight increase for the new -900 variant is around 5,900kg.
"The -800ERX is a commercial offering and the -800 is the most popular sub-model, so this is an extension of that family for a unique sub-market," says Delaney, who adds that delivery of the first airframe for flight tests would be timed for 2007. The schedule for the -800ERX is driven by the MMA contest, which, if Boeing wins, it estimates could generate a requirement for up to 300 military aircraft in addition to whatever commercial sales are achieved. Around 150 of these military airframes would be directly for the US Navy P-3's replacement, while the balance would be for international military customers.
The target for the -900X, by contrast, is driven directly by prospective commercial sales. The planned entry-into-service target for the higher weight -900 version has slid consistently because of poor market conditions, with Boeing having to push back the target for flight tests from 2005 to 2006. The -900X, pending full go-ahead, will also kick-start development of a flat aft pressure bulkhead that would then become standard across all new-build 737s, adds Delaney.
GUY NORRIS / LOS ANGELES
Source: Flight International
