Boeing is scheduled to start delivering the tankers to Air Force bases in August.
"Execution of the current schedule assumes historically unrealistic test aircraft fly and re-fly rates," the report says. The three-page Pegasus section from the report is below.
It's not the first time that the military testing overseers have flagged the aerial refueling program's delays.
Made by Chicago-based Boeing in Everett, the Air Force tanker is a militarized version of the Boeing 767-200ER (extended range) wide-body aircraft featuring a 787 Dreamliner cockpit.
It is designed to refuel military planes and helicopters in the air using a tail boom and fuel hoses that extend from the wingtips and belly. It can also carry passengers, medical patients and cargo, and can itself be refueled in air by other tankers.
Boeing won $2.8 billion for initial production of 19 tankers last year. Boeing plans to build 179 of the aircraft to replace older Boeing KC-135 Stratotankers.
Boeing suspended aerial refueling testing early last year to redesign the boom control system and discovered other issues, including cybersecurity vulnerabilities. Boeing last year moved back the delivery date for the first tanker from this March to August.
Boeing and the Air Force have yet to complete ground and flight testing of defense systems including electromagnetic pulse shielding and nuclear flash curtains. The aircraft is designed to survive nuclear, chemical, biological and radiological attacks.
(Jim Hammerand - Puget Sound Business Journal)