The first flight of KC-46 Pegasus aerial refuelling aircraft is expected to be delayed after the use of incorrect chemicals in the plane’s fuel system, the Boeing company has said.
The KC-46 programme has already been delayed due to wiring and supplier issues.
Boeing spokesman Chick Ramey was quoted by Reuters as saying: "This issue will extend the projected first flight date by roughly a month beyond the previous plan to fly (the plane) in late August, early September.
"(A) fuel substitute supplied by a vendor had been labelled compliant for a particular military use, when in fact it was not."
The company said the chemical was being used to approximate the weight of actual fuel in the refuelling boom.
Developed from the Boeing 767-200ER, the US Air Force’s KC-46 is a military aerial refuelling and strategic transport aircraft, designed to replace the USAF’s ageing fleet of KC-135 Stratotankers, which served as its primary refuelling aircraft for more than 50 years.
The USAF is scheduled to take delivery of 18 KC-46 aircraft from Boeing, which starts from 2017 and will continue until 2028.
Recently, the aircraft test programme successfully completed flight flutter tests on EMD 1 aircraft, marking the conclusion of an integral part of the certification process.
Flutter testing is a prime requisite for aircraft capabilities testing that ensures the design of the new aircraft is structurally sound.
The completion of this testing will result in an expanded flight envelope and the ability to safely put more crew on board for further testing.
Image: Boeing KC-46 Pegasus aerial refuelling aircraft. Photo: courtesy of Boeing photo illustration.