The Federal Aviation Administration is trying to determine whether the young pilot who died in a helicopter crash during a Kaua'i firefighting operation on Christmas Day was properly certified to be doing that work, according to a federal air safety investigator.

Jonathan D'Attilio, 20, died two days after the MD 369 helicopter he was flying crashed into a Kaua'i reservoir as D'Attilio attempted to collect water in a 140-gallon bucket to drop on a brushfire.

Nicole Charnon, air safety investigator for the National Transportation Safety Board, said D'Attilio had a private pilot's license for airplanes and helicopter operations, but did not have the commercial pilot's license the FAA generally requires for pilots who fly for federal, state or local agencies.

Charnon said, however, FAA regulations also note the commercial pilot's requirement may be waived in emergencies, and that it is up to the FAA to determine whether the situation on Kaua'i on Christmas Day qualifies as an emergency.

Kaua'i Fire Chief Robert Westerman has said Kaua'i fire officials have an "on-call" arrangement with Inter-Island Helicopters through which the company is paid $750 per hour to assist with firefighting operations.

Inter-Island Helicopters is owned by D'Attilio's father, Ken D'Attilio. Jonathan D'Attilio was president of the company.

Ken D'Attilio said last night FAA regulations are clear that a commercial pilot's license is not required for firefighting operations. Jonathan D'Attilio needed an endorsement showing he was qualified to do the firefighting work, and he had that endorsement, Ken D'Attilio said.

The Transportation Safety Board's preliminary report on the crash states that a witness near the crash site reported seeing the helicopter rise up from De Mello Reservoir with the bucket attached. The nose dipped slightly, the witness said, then the helicopter rotated quickly and violently counterclockwise.

The witness reported hearing the engine racing loudly as the helicopter spun. The engine then shut down or stalled as the helicopter slowed its spin, leveled out and began to descend back down toward the reservoir.

Rescuers found the helicopter almost entirely submerged in the reservoir except for its left skid, according to the report.

Ken D'Attilio has said he and his son had shared dual controls during previous water drops over brushfires, but said he believed the flight on Christmas Day was Jonathan D'Attilio's first solo flight using a water bucket dangling on a 25-foot line below the helicopter.

Ken D'Attilio said his son was a good and careful pilot, and said he believes investigators will eventually find some mechanical failure was to blame for the crash.

"My question is what happened to cause the aircraft to spin?" Ken D'Attilio asked. "I have no idea. I don't know."

The NTSB investigation has not been completed, and the preliminary report does not give a cause for the crash.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.