Federal investigators say they found no evidence of any mechanical malfunctions in an experimental airplane before a 2012 crash that killed Micron CEO Steve Appleton.
The National Transportation Safety Board also reported Tuesday that Appleton didn't take specialized training before crashing while taking off from the airport in Boise, where Micron is based.
The agency's report doesn't say what caused the crash that killed the head of the memory chip company.
It was unclear when the agency will release a final probable cause report.
Appleton, a stunt pilot who survived a similar crash in 2004, was 51.
The NTSB says witnesses reported the plane took off but only climbed to about 200 feet before it steeply banked or rolled, appeared to stall and crashed.