The 72-year-old actor's two-seater plane smashed into a golf course in Las Angeles in early March after he was forced to make an emergency landing due to an engine malfunction and the National Transportation Safety Board's report into the crash has now established what happened.
According to TMZ, the report states the carburetor's main metering jet became loose, which likely stemmed from when the plane was rebuilt 17 years earlier.
The 'Star Wars' actor - who is married to actress Calista Flockhart - suffered injuries including a large laceration to his head, as well as broken bones in the accident, and the report says the fact his shoulder harness was not properly reinforced contributed to their severity.
The report also says Ford's shoulder harness was not properly reinforced, which contributed to the severity of his injuries.
Harrison, who got his pilot's license 19 years ago, is believed to own approximately 11 private planes in Los Angeles and is an avid flyer.
But he previously crashed a Bell chopper in 1999 while flying in California.