PORTLAND — A National Transportation Safety Board investigator says the propeller wasn’t spinning when a small plane crashed after taking off from the Portland International Jetport, killing two men.

Atlanta-based investigator Butch Wilson says 42-year-old Mark Haskell of Brunswick was maintaining his pilot certification with a flight instructor when his Yak-52 apparently lost power after taking off on Saturday. Wilson says the plane reached 300 feet, wobbled, turned left and lost altitude.

The plane went down at a steep angle, and the cockpit caught fire. Killed was Haskell, who was the plane’s owner, and 66-year-old Thomas Casagrande of Portland, a retired military test pilot.

Wilson says his investigation into the cause of the crash will “start with the engine.”