In response to airline feedback, Boeing is mulling further refinements to its proposed 747-400X Quiet Long Range (QLR) model that would provide extra range and a marginal increase in capacity without affecting the demand for stringent QC2 noise compliance at London Heathrow Airport.

Airlines are asking for 14,800km (8,000nm) range to ensure economical non-stop flights between the US East Coast and Asia. Changes would focus on adding up to 3,790 litres (1,000USgal) of fuel to an expanded horizontal stabiliser fuel tank and a new fuel tank housed in the vertical fin. The fuselage forward of the wing leading edge would be stretched by 2m (80in) or four frames, to offset the shift in centre of gravity while providing space for an extra row of business class seating and extra lower deck cargo.

The 747-400XQLR configured with the General Electric CF6-80C2B9F engine and a maximum take-off weight (MTOW) of 396,900kg (875,000lb) would meet QC2 compliance but with a maximum range of only 13,900km. Boeing has opened talks with Rolls-Royce to also offer the aircraft with the Trent 600, which, the manufacturer claims, would meet demands for QC2 compatibility at the 747XQLR's 420,000kg MTOW (Flight International, 3-9 September).

Major challenges for Boeing will be to strip weight out of the aircraft elsewhere to stay within the QLR's upper MTOW limit and strike a deal with R-R to harness the Trent 600's promised improved operating performance. Talks between the two companies have been ongoing since early September, with little sign of progress. A key consideration for R-R is the potential size of the QLR market in the face of competition from the new Airbus A380.

Cathay Pacific Airways is understood to be leading the group of potential 747-400XQLR launch customers, with a requirement for up to 10 passenger and freighter versions. Other interested carriers are Cargolux, Korean, Qantas and Singapore Airlines.

Source: Flight International