Andrew Doyle/FRANKFURT
Boeing has decided against attempting to certificate its proposed stretched and extended-range 747X models as derivatives of the 747-400.
The US manufacturer has applied to the US and European airworthiness authorities to certificate the pair as all-new aircraft designs under the same rules as those for the rival Airbus A380.
"If we were to have applied for derivative certification we would have had to argue over which parts of the aircraft we could change and which parts we could not change," says Boeing vice-president and general manager 747 programme Walter Orlowski. "We determined that there was a great amount of risk in doing that," he adds.
He admits that the decision is likely to increase development costs slightly, though this will be offset by removing the need to devote "time and energy" to resolving issues associated with a derivative certification.
The move also eliminates the potential for another transatlantic row over so-called "grandfather rights", which allow derivatives to be certificated under different rules to an equivalent all-new design.
The issue last came to the fore when Boeing attempted to gain European approval for the 737-800. Europe's Joint Aviation Authorities (JAA) demanded changes to the twinjet's overwing exit hatches to enable them to be opened more quickly during an emergency, substantially delaying the type's entry into service.
European introduction of the 747-400 was also delayed by a JAA demand that the upper-deck floor be strengthened to provide better protection for control lines in the event of rapid decompression.
After a meeting with Lufthansa executives in Frankfurt, Orlowski said he remains confident of garnering sufficient commitments to launch the 747X this year despite FedEx's recent decision to sign up as the seventh A380 customer.
A formal go-ahead for the 747X is required by the end of the year to ensure that the September 2005 in-service date can be met. Orlowski will not confirm the number of commitments required for a launch, saying: "I think the opportunities are still there. We'll look at each transaction individually and then go back to our board." Airlines currently conducting large aircraft evaluations include Lufthansa, Cathay Pacific, Cargolux and Atlas Air.
Boeing continues to refine the design of the high-capacity 747X Stretch and ultra-long-range 747X. Recent changes include a switch to 767-400ER-style raked wingtips which Orlowski says are cheaper to manufacture and weigh slightly less than either conventional, or "blended", winglets.
The new models will have lighter fuselages constructed using fewer parts than are used in the current 747, and feature the new passenger windows designed for the 777 and later introduced on the 767-400ER, says Orlowski.
A modified wing incorporating a root insert will enable the standard-body 747X to carry 430 passengers over a range of 16,640km (9,000nm), while the Stretch will seat 504 passengers for a 14,450km mission. Freighter versions of both are also being offered. Development costs are estimated at $3-4 billion, says Boeing.
Source: Flight International
