“The lag in accomplishing the intended 2012 flight testing content defers testing to following years, and in the meantime, will contribute to the program delivering less capability in the production aircraft in the near term,” said the report prepared by Michael Gilmore, the Pentagon’s director of operational test and evaluation.

Gilmore said the program remained saddled by a high level of concurrency or overlap between development, production and testing. The Pentagon planned that overlap from the start, but its top weapons buyer, Frank Kendall, has said that in retrospect, that approach amounted to “acquisition malpractice.”

CONDUCTING FLIGHT TESTS

The report said the program conducted 1,092 flight tests in 2012, 18 percent more than the 927 flight tests planned, running more tests than scheduled for the Marine Corps B-model and the Navy’s C-model or carrier variant.

But it fell short of the flight tests planned for the Air Force’s conventional takeoff A-model. That model completed 30 percent less test points than planned due to operating limits on the plane and problems with the weapon bay doors, it said.

It said flight tests were also limited by problems with the air refueling system, which led to restrictions on all A-model planes and required new instrumentation to isolate the cause.

The plane’s stealthy coatings - which make it nearly invisible to enemy radars - were also peeling off on horizontal tail surfaces due to higher-than-expected temperatures during high-speed, high-altitude flights, the report said.

The Marine Corps version of the plane flew more than planned but lagged its target for test points by 49 percent due to issues with the weapon bay doors and an engine lift fan needed for that B-model’s vertical landings, the report said.

The lift fan is built by Rolls Royce, a supplier to the engine maker, Pratt & Whitney, a unit of United Technologies Corp.