Boeing has dropped the empty weight of the latest 747-8 Freighters by 2.5t compared to the aircraft delivered a year ago and tweaked the aileron configuration to boost aerodynamic performance.
The improvements were revealed at an industry conference on 29 November by a Cargolux executive, who noted the long-awaited weight reduction arrived with the delivery of the carrier's sixth 747-8F in mid-November.
"Strangely, we're very happy" with the new aircraft's performance, Yves Germeaux said at the Ascend Aviation 2020 Finance Forum, a Flightglobal-sponsored event, in San Francisco.
Cargolux helped Boeing launch the 747-8F with the first order, but then refused to accept delivery of the first 747-8 for several weeks last year due to disputes about contractual guarantees. Another carrier, Atlas Air, cancelled orders for three 747-8Fs last year partly due to performance issues.
But the Luxembourg-based carrier's position appears to have softened with the latest arrival in its fleet.
"The performance, with [the improvements] all in mind, is quite close to what Boeing had in mind," Germeaux added.
In response, Boeing agreed "overall" with the Cargolux assessment of the performance of its sixth 747-8F, but also noted that some customers have reported a 1% fuel burn improvement compared to Boeing's promises.
Boeing has not publicly updated the empty weight specification on the 747-8F since December 2011. At that time, airport planning documents released by the airframer showed the baseline weight had already started decline since first delivery in October 2011, falling by 363kg (800lb) to 190.9t.
At the same time, Boeing increased maximum take-off weight for the 747-8 by 1.3% to 448t, based on the results of a flight loads survey that showed extra payload margin in the airframe.
Since that time, the Freighter model has also benefitted from improvements introduced with the certification of the passenger 747-8 Intercontinental model on 14 December 2011.
Boeing now says that the 747-8I added enhanced positioning of the fly-by-wire outboard aileron in cruise, and that feature was retrofitted on the 747-8F. More improvements are expected to be introduced next year, with the second performance improvement package (PIP 2) of the General Electric GEnx-2b engines.
Flightglobal senior reporter Edward Russell contributed to this article.