A federal report on a 2013 plane crash, in which the state's health director died, didn't undergo a key inspection of its engine turbines.
The National Transportation Safety Board also said that five passengers told investigators that they weren't given a safety briefing before take-off from Kalaupapa, and that state Health Director Loretta Fuddy was wearing an infant's safety vest that didn't properly inflate.
"It was a two-fold problem: The life vest and then the problem with the engine when the compressor failed it caused a catastrophic failure and the plane just went right into the water," said Rick Fried, attorney for Fuddy's family.
According to the National Transportation Safety Board report, Makani Kai Air didn't conduct key metallurgical tests on the turbine blades, which some say have a tendency to fail. The NTSB said all of the blades on the single-engine Cessna Caravan were damaged.
"There's been a history of these blades failing so it was our thought that particularly in this engine, especially in this caravan, that there should have been a much better inspection," Fried said.
The NTSB said that under engine manufacturer Pratt and Whitney's guidelines, metallurgical tests on the plane's turbine blades are required after 3,600 hours of flight time.
But the federal agency said Makani Kai opted to place the engine under a separate inspection program known as a Maintenance on Reliable Engines or MORE plan, which extended the overhaul period to 8,000 hours. That program didn't require a metallurgical test of the turbine blades at the time.
"According to the operator, the combined documentation between the MORE literature and the (Pratt and Whitney) manual ... was confusing," the NTSB said.
"Since the time before overhaul extension was granted ... which did not contain blade sectioning instructions, they deemed that this task was not necessary."
But Makani Kai President Richard Schuman said that such an inspection probably wouldn't have detected defects in the blades. He said the carrier inspects its planes more frequently than federal regulators and the manufacturer require.
He also disputed passengers' claims that the pilot didn't give proper safety instructions.
"The pilot recalls he gave a briefing. That's standard procedure. Every time the pilot takes off or lands in an airplane, they give a safety briefing," Schuman said.
A lawsuit filed on behalf of Fuddy's family two years ago was settled last August. The details were not released.