Guy Norris/SEATTLE

The Boeing board has given its civil-aircraft sales team authority to offer a growth version of the 747-400 with a maximum take-off weight of 413,140kg and a range of up to 14,245km (7,700nm).

The decision is the first significant growth step for the aircraft since the abandoned 747-500X/600X programme, and is being seen as key to a longer-term effort aimed at keeping the aircraft competitive with the proposed Airbus Industrie A3XX.

The decision follows a request from Qantas for Boeing to build its three new 747s to an increased-gross-weight (IGW) specification, allowing the Australian carrier to overcome payload/range restrictions on several major routes.

The new -400 model will be available for delivery from the fourth quarter of 2000, and would incorporate structural strengthening around the centrebody, wing-to-body join, wing, flaps and landing gear. The basic heavyweight model will have a range of 13,400km, with progressive range increases available with supplemental belly-tanks. Range with one tank increases to 13,875km and, with two, to 14,245km. Each tank holds 11,600litres and, when added to the standard 747-400 fuel load, will produce a maximum capacity of 240,000litres.

Although many of the proposed changes are relatively straightforward, the most significant modification is likely to be the strengthened gear. With earliest availability in late 2000, Boeing would miss the current Qantas delivery schedule by six months, even if it committed to a launch early in 1998. This means that the initial aircraft would operate at current -400 weights until the higher-weight gear could be retrofitted.

The development of the new gear, however, plus the other structural changes, will also provide opportunities for further growth. Complete with wing-root inserts, the next step variant would offer a range of up to 15,200km and provide the basis for a stretched version, with seating for 485.

Source: Flight International