HONOLULU -- The crash of a Hawaii Air National Guard F-15 fighter jet earlier this year was probably caused by rudder failure, according to an Air Force investigation.

The Coast Guard rescued the pilot of the Hawaii Air National Guard F-15 jet after it crashed 60 miles off Oahu on Feb. 1.

Veteran pilot Lt. Col. Christopher Faurot suffered minor injuries in the crash. His $44 million plane was a total loss, left under 15,000 feet of ocean.

An Air Force panel released its findings on the crash on Tuesday.

"They did not find any definitive root cause, because, of course, the aircraft was never recovered," Lt. Col. Charles Anthony said.

The investigative panel found the plane's two rudders most likely failed, causing a rolling motion to the left that the pilot was unable to correct.

The Air Force grounded its entire fleet of F-15s in November, after an F-15 in Missouri disintegrated in the air.

"As far as the investigators were able to determine, they don't believe that there's any connection between what happened in Missouri and what happened here in Hawaii," Anthony said.

Anthony said the two crashes involved two different parts. The Missouri crash was a structural problem, while the Hawaii crash appears to be mechanical, he said.

The Hawaii National Guard grounded all 20 of its F-15s after the crash off Oahu in February.

They returned to the air a few days later when a safety review was completed.

"Prior to this, we had more than 70,000 hours, which is just an amazing total of hours without any kind of mishap of this type. So, this is definitely a very, very rare occurrence," Anthony said.

It was the first crash since the Hawaii guard began flying F-15s in 1987.