WASHINGTON, July 2 (Reuters) - The Navy on Monday blamed a rare two-engine mechanical failure for the April crash of an F/A-18D fighter into a Virginia apartment complex that caused minor injuries.
An investigation of the crash, on April 6 in Virginia Beach just over a minute into a training flight, showed that the right engine compressor stalled and the left afterburner blew out, said Rear Admiral Ted Branch, the Atlantic naval air commander.
The root cause of the crash remains under investigation but may never be known since many parts were destroyed in the crash and a subsequent fire. A leaking fuel cap is a possible culprit, he said.
"Let me stress again, this type of concurrent dual-engine malfunction is extraordinarily unusual," Branch told a news conference carried online.
"We are very confident we can continue to operate the F-18 and fly it safely and effectively, not only here in Virginia Beach but around the world."
Five residents of Virginia Beach were injured and six buildings damaged when the 11-ton F/A-18D, from nearby Naval Air Station Oceana, slammed into the Mayfair Mews apartment complex.
The plane's two-man crew ejected safely with minor injuries. The supersonic fighter was a total loss.
Investigators found that the right F404-GE-400 engine stalled just after takeoff when the compressor ingested fuel, Branch said. The left afterburner then blew out, most likely because of fuel delivery failure.
Branch said that the General Electric Co engine was known to be highly reliable, with only 0.16 failures per 100,000 hours of operation.
The pilot reported noise and vibration from the right side of the aircraft as its nose wheels lifted off at takeoff. He believed that the plane had blown a tire and left the landing gear up, slowing the aircraft even as the engines failed.
The pilot also rejected dumping an outside fuel tank since he was over a populated area, Branch said.
The Navy has recommended improved training for dealing with engine failures and loss of thrust, especially by raising the landing gear and by dumping fuel.