Former head mechanic John Liotine blew the whistle to investigators after he claims to have witnessed supervisors falsifying maintenance records -- which he says could have endangered the lives of passengers. He voiced his concerns about the maintenance of the MD-80 aircraft months ago.
"There is a lot of pressure to get aircraft out on time, fly on schedule," Liotine said.
In documents obtained by CBS News, Liotine claims management approved maintenance checks that never happened.
The head of Alaska Airlines says they go above and beyond other airlines in their maintenance.
"We have done a thorough investigation and we have found nothing," said CEO John Kelly. "We know we have the finest group of maintenance people out there."
Law enforcement sources tell CBS News this is a serious investigation, but caution drawing any connection between these maintenance problems and Monday's deadly crash.
However, the airline has been hammered by other accusations by its own employees, who claim that fumes that can seep inside the MD-80 cabins have caused serious health problems. Alaska airlines continues to deny those allegations as well.
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