* Pentagon's chief tester cites issues with radar, ejection seats
* Defense officials see no showstoppers in report
* Air Force, Pentagon say confident training should continue
By Andrea Shalal-Esa
WASHINGTON, March 6 (Reuters) - Some students in the U.S. Air Force's F-35 fighter pilot school took their first flights on Wednesday in the new radar-evading jet as a report by the Pentagon's chief tester found fault with early versions of the plane's radar, pilot helmet and other systems.
The report by Michael Gilmore, the Defense Department's director of operational test and evaluation (DOT&E), was sent to Congress last month, but was first published by the watchdog group, Project on Government Oversight, on Wednesday.
Gilmore has been critical of the U.S. Air Force's decision to start training F-35 pilots while the new Lockheed Martin Corp plane is still in development, arguing that pilots are at risk until the jet has amassed more flight hours in testing.
The latest report by Gilmore's office comes at a difficult time for the $396 billion weapons program, which has already been grounded twice this year, and faces possible cuts as a result of the mounting pressure on the U.S. defense budgets.
Defense officials said they were not surprised by the negative tone of the report given Gilmore's views, but said it included no "showstoppers" that jeopardized the program, which must complete several more years of development before it moves into combat testing and is declared ready for operational use.
The report reviewed an "operational utility evaluation" conducted by the Air Force last year before it decided to start training seasoned pilots to fly the F-35 fighter. The training lasts three months and includes time in the classroom, on sophisticated simulators, and in the air.
This year, the Air Force says it plans to train about 72 pilots and 711 mechanics to maintain the new planes. The first official class just completed the academic portion of their training and are now taking to the skies.
Gilmore's report said there was little to be gained by training pilots at this point, given technical issues and flight limitations on the new airplane.
"The limitations, workarounds, and restrictions in place in an air system this early in development limit the utility of training," the report said. "Little can be learned from evaluating training in a system this immature."
The report said the plane's radar, the display in the pilot helmet and the cockpit interfaces for controlling the plane's radios and navigational functions all needed improvement.
Pilots were unable to fly at night or during cloudy weather during the Air Force evaluation, given the immaturity of the current version of the plane. They were unable to practice advanced handling, slow flight, dives and use of the plane's afterburners, according to the Pentagon report.
It said pilots faced risks because the plane's water-activated ejection system was not installed on the early jets, the ejection seat had not yet been fully tested, and the jet did not have a qualified lightning protection system.
The report also included comments from the four experienced pilots who flew the jets during the Air Force evaluation, in which they expressed concerns about problems with the plane's radar and visibility during combat or more intense training.
Referring to close-range visual combat, one of the pilots said, "The head rest is too large and will impede aft visibility and survivability during surface and air engagements," and, "Aft visibility will get the pilot gunned every time."
Winslow Wheeler, a long-time critic of the plane who posted the report for the watchdog group, said the new report showed that the Air Force, or conventional takeoff and landing model of the F-35 was "flawed beyond redemption."
The Air Force's Air Education and Training Command, which approved the start of training in December, said it believed the training system was perfoming adequately and should continue.
Lockheed, the prime contractor on the F-35 program, said it agreed with the Air Force's decision to start training pilots on the F-35, and said it was confident that the service was able to conduct safe and effective flight training operations.
It said it would continue to refine the operating and tactical procedures for the jet as needed.
Joe DellaVedova, spokesman for the Pentagon's F-35 program office, said Gilmore's latest report was based on the Air Force's report about its evaluation, which had found no reason to hold off on training experienced pilots to fly the new plane.
He said the Air Force and F-35 program office already knew about the issues raised in the report and were working to resolve them.
Northrop Grumman Corp and Britain's BAE Systems are key subcontractors on the plane. United Technologies Corp's Pratt & Whitney unit supplies the engine for the single-seat, single-engine F-35.