A single-engine plane whose crash killed the pilot and 16 skydivers carried contaminated fuel and may have been overloaded, National Transportation Safety Board Chairman Jim Burnett said yesterday.

He said that a black discoloration was found in the right fuel tank of the Cessna 208 Caravan and that investigators did not know what had contaminated the fuel.

The Federal Aviation Administration said it grounded the plane Friday because of contaminated fuel, and Burnett said the plane's owner apparently took off without correcting the problem, which would have been a violation of FAA rules.

Burnett, speaking at the crash scene 50 miles south of Atlanta, said maintenance workers at an Atlanta air-freight company reported that last Thursday the plane's fuel was "the color of black coffee" instead of its normal amber.

The plane's weight limit for its flight on Sunday was 3,115 pounds, he said. The West Wind Sport Parachute Center estimated that each parachutist carrying equipment would weigh 200 pounds.

"I'll let you do the mathematics," he said.

The weight of the pilot and the plane's fuel would be added to the estimated 3,200 pounds weight of the parachutists in calculating the load.

However, Burnett said the NTSB had not determined the actual weights.