Senior Air Force generals overturned the findings of their own investigation team and ruled that the fatal crash of a CV-22 Osprey in Afghanistan in April was largely due to flight crew mistakes and not a mechanical problem.

But the general who led the crash investigation said Thursday that there was strong evidence to indicate that the $87 million-plus aircraft, which has a history of technical problems, experienced engine trouble in the final seconds leading to the crash.

Four of the 20 people on board were killed in the April 9 crash, including the chief pilot.

Crash site evidence showed that the pilot tried an emergency roll-on landing, as if it were a conventional airplane, rather than a vertical, helicopter-type landing the Osprey is designed to perform. The pilot performed the landing so well he nearly saved the aircraft and prevented a greater loss of life, the Air Force's Accident Investigation Board concluded in the report released late Thursday.

"I think they knew they were going down and they had some kind of power problem," chief investigator Brig. Gen. Donald Harvel said in an interview with the Star-Telegram after the report was released.

The pilot, Harvel said, "made what is in my opinion a perfect roll-on landing," but the aircraft's nose landing gear collapsed and the aircraft flipped tail-over-nose when it ran into a 2-foot-deep drainage ditch.

In his report, Harvel wrote that the preponderance of evidence pointed to an engine problem.

"It is unlikely that this very experienced and competent [pilot] would have chosen to execute a roll-on landing on rough terrain if he had power available to go around and set up for another approach."

But the senior Air Force officer who ordered the investigation disagreed.

To read the complete article, visit www.star-telegram.com.