GULF SHORES, Ala. (AP) — A preliminary report about a plane crash that killed two people on the Alabama coast this month says everything seemed normal until the aircraft went down.

An initial report by the National Transportation Safety Board says the single engine on the plane sounded strong.

But the American Champion aircraft went down while the pilot was attempting to pick up an advertising banner at the Gulf Shores airport on Aug. 4. The pilot and a passenger were killed.

The report says a member of the ground crew reported that everything seemed normal until the plane was about 300 feet high. The witness says the right wing dropped and the plane entered a spin, rotating several times before it hit the ground.

The report doesn't state a cause of the crash.