GONZALES — The National Transportation Safety Board said Friday that a small airplane piloted by a Louisiana plastic surgeon flew into moderate-to-heavy rain and was operating at an excessive speed before breaking up during a steep fall and crashing in Tennessee two weeks ago.

The NTSB's preliminary accident report suggested no cause for the crash, instead providing a largely technical look at the flight's final moments. Investigators did note that the airplane surpassed its safe operating speed after changing course abruptly above the Tennessee hills.

The crash killed Dr. Lucius Doucet and two of his adult children. There were no survivors when the 58-year-old single-engine Beechcraft V35 crashed near Leipers Fork, Tennessee, about 20 miles southwest of Nashville on May 15. Doucet's children, Giselle and Jean-Luc Doucet, died two days before they were to graduate from LSU.

The report said Doucet had been flying at 9,000 feet then descended to 7,000 feet before approaching Nashville's airspace. After being told to climb back to 9,000 feet, Doucet flew 500 feet higher and had to be told to drop back down. "This was acknowledged by the pilot and was the last transmission received from the flight," the NTSB report said.

While the plane was flying due north to get back on its original track, it entered moderate to heavy rain, and in doing so descended slightly to 8,900 feet, the NTSB said. Doucet turned to the northeast for a time, then the plane turned to the right in almost the opposite direction. The airplane's forward speed increased from 180 knots to 214 knots. 

A Beechcraft V35's operators manual advises pilots to not exceed 195 knots.

In the last moments of radar contact, the plane was dropping 5,000 feet per minute, while its forward motion slowed to 43 knots. Eventually the plane fell at a rate of 15,000 feet per minute before all contact was lost.

"Several witnesses described that they heard the airplane as it descended and that they heard a loud 'pop,'" the NTSB report said. One witness recorded a video of pieces of the airplane falling through the clouds.

Damage was scattered in a fan pattern oriented toward the west. The engine and propeller were found 8 feet deep in a lake. 

Doucet was an experienced pilot, with 366 hours of flying time, including 14 in a Beechcraft V35. He had purchased his plane last December.