KC-46 Tanker Image Credit:Boeing US Air Force KC-46A Pegasus next generation tanker program has slipped the first flight schedule due to ...
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| KC-46 Tanker Image Credit:Boeing |
The issue will delay the first Engineering and Manufacturing Development (EMD) aircraft's flightline debut to first quarter of 2015.
During an audit, FAA and Boeing engineers found the multiple wires originating from the same system for redundancy were placed close to each other, risking failure during a emergency. The redundant wires need to be spaced out to sustain an emergency like a fire, taking out all of wires preventing loss of essential systems infight.
Maj. Gen. John Thompson, USAF Program Executive Officer for Tankers, acknowledged the complexity of the Pegasus's advanced construction at the Air Force Association’s Air & Space Conference and Technology Exposition on Sept. 16.
“Wiring that represents redundancy cannot be placed next to each other in the same bundle,” Thomson said. “Your back-up has to be in another physical location on the aircraft so that if one gets taken out, you don’t lose the capability.”
The commercial version of the Boeing 767 aircraft on which the KC-46A is based, contains about 70 miles of wiring, while the KC-46 has about 120 miles. Because of this, the relocation and installation of new bundles impacted the assembly and testing timeline, resulting in “slower than planned” delivery he said.
Boeing had to redesign the electrical layout of the jet at cost of $272 million, reinstalling 350 wire bundles of the total 1,700.
“This is not a big performance issue, it’s a compliance issue and something we’d rather catch early than later, while it only requires a minor redesign,” he said. “But … we’re eager to get into flight testing and unfortunately this production challenge (has taken some) of our schedule margin, so schedule performance has to improve.”
Once the assembly returns to schedule, officials will return to a “test once” strategy intended to better leverage a single test event to accomplish multiple certifications before flight.
The first test aircraft a Boeing 767-2C, without the refuelling boom and other tanker equipment is expected fly by 2014 end. The four EMD aircraft being built at Boeing's Seattle plant will follow in 2015.
The KC-46A is intended to replace USAF's aging fleet of KC-135 Stratotankers which has been the mainstay of tanker fleet for more than 50 years.
Originally acquired as an interim solution to an urgent need for increased global mobility, 4,000 of the originally 700 produced KC-135 are still in service, but increasing cost to support and its age-related problems prompted USAF to initiate the $52 billion KC-46A program.
The program plans to produce 18 tankers by August 2017 and 179 aircraft by 2027. But even when the program is complete in 2028, only less than half of the current tanker fleet will be replaced, still flying over 200 half-century-old KC-135s.
Despite government shutdown and sequestration, the program was not affected by funding. KC-46A is among the three priority projects for USAF along with F-35 Lightning II fighter and the Long Range Bomber.
The sixth generation tanker can offload 94 tons of fuel through an advanced KC-10 boom, a center mounted drogue and wing aerial refueling pods to refuel multiple types of receiver aircraft.
Boeing was awarded a $4.9 billion fixed price contract for the EMD phase of the KC-46 program on Feb. 24, 2011.
The KC-46A will feature Boeing 767-200ER (extended range) commercial aircraft airframe, with model 767-300 wings, cargo door and landing gear, and 787-model cockpit displays.
Other than aerial refueling, KC-46A can also airlift troops and cargos. It has a maximum cargo capacity of 29 tons and can carry 58 troops during normal operations and up to 114 during contingency operations.
