Guy Norris/Los Angeles
UNITED AIRLINES admits that its first Boeing 777s is overweight, but is still satisfied with the aircraft's performance. New 16G crash-worthy seating is the largest single contributor to the higher-than-expected operating empty weight (OEW) of the initial aircraft, says the carrier.
In United's configuration, the aircraft's OEW of 143,075kg is around 7,965kg more than Boeing's published figure of 135,110kg. "We attribute around 2,000lb [900kg] of that to the strengthened 16G seating," says United 777 programme manager, Gordon McKinzie. "We thought we were pushing the allowables on floor strength at the beginning, but it's OK now."
McKinzie says that United's own furnishings, accessories, seating and cabin fittings are largely responsible for the weight difference. "The aircraft contracts have weight guarantees built into the empty weight, and Boeing is well within it.
"At one point, early in the programme, weight was really out of control and Boeing went on an emergency diet. We're OK now, we are where we want to be," says McKinzie. A host of other "incremental" factors also drove up the weight adds McKinzie. Although United reduced the number of seats from 300 to 292, the penalty of the higher OEW is believed to be up to 40 passengers on long-duration flights up to 12h.
Despite the heavier-than-expected OEW, McKinzie says: "Pounds of fuel per pounds of payload we're still better off than other types like the A330 which we looked at, mainly because we can carry much more payload - particularly cargo". United assessed the Airbus A330 and McDonnell Douglas MD-11 before opting for the 777. The A330 was rejected mainly because of United's exacting requirement for hot-and-high-performance guarantees on the long non-stop Denver to Honolulu route.
McKinzie says: "We've had the usual growing pains," but adds that the first six aircraft are doing so well that the special fleet-maintenance watch, common for new types, has now been dropped. Early incidents include cracks discovered in an elbow of an oil line in the aircraft's PW4084 engine. Pratt & Whitney say that cracks were discovered in 20% of around 50 PW4000 series engines powering 777s and A330s. It adds that no aircraft have been grounded by the discovery, but it is replacing the elbow with a block joint.
"Despatch-reliability-wise, they're doing 2.5% better than the 767 or 747 were at this point in time. Load factors are up in the high 90%," says McKinzie. He also refutes allegations that 777 operations are hampered by incompatibility with gates. "There's only one airport (Amsterdam) where we have to shut down the engines and be towed in. That's because of an over-the-wing loading bridge." McKinzie also says that the large engines do not slow down start-up procedures.
Source: Flight International
