The pilot of a helicopter that crashed in Sanford on Saturday was listed in critical condition Sunday night at Maine Medical Center in Portland as federal transportation officials continue to investigate the accident.

Jack White, 50, of Bowdoinham was piloting the Robinson R44 helicopter – a light four-seat model – when it fell next to the runway at Sanford Seacoast Regional Airport on Saturday morning, according to the Federal Aviation Administration and local police.

The National Transportation Safety Board is investigating how the helicopter spun out and crashed, a process that could take more than a year to fully play out, according to spokesman Terry Williams.

Although the NTSB may release a preliminary report within 10 days, Williams said, there were no updates to provide on Sunday.

Meanwhile, the owner of the helicopter says he’s worried more about the pilot than his lost machine.

“We’ve just got our fingers crossed that the pilot’s OK. I’m not concerned about the helicopter,” said James Knowles of Lee, N.H., who owns the aircraft through an LLC that leases it to a flight school called York County Helicopters.

In a telephone interview Sunday, Knowles said the R44 was the only helicopter he leased out in this way. He said he complied with FAA regulations requiring regular inspections and maintenance, as well as with manufacturer-mandated safety upgrades.

The helicopter was in fine shape “as far as we know,” he said, adding that the NTSB would have the final word on what went wrong.

Witnesses reported that the helicopter appeared to be practicing landing and near-ground maneuvers when it entered an “uncontrolled spin” and hit the ground, Sanford police said Saturday.

Police Sgt. Jason Wagner said White’s flight was part of his helicopter licensing process. White had flown from the Sanford airport to multiple Maine and New Hampshire locations and was returning to Sanford to complete his flight when the crash occurred, Wagner said.

Robinson R44 helicopters are among the world’s popular civilian models, and also see use with police departments.

Robinson Helicopter Co. in recent years has come under scrutiny from the Los Angeles Times, which published an analysis indicating that the R44 model has a high rate of deadly accidents per hours flown. The aviation company disputes that analysis, saying the FAA undercounts the number of hours its helicopters spend in the air.

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