LOS ANGELES (AP) — A problem with a carburetor part led to engine failure and the crash of a vintage airplane piloted by actor Harrison Ford in California earlier this year, federal investigators said Thursday.

The part known as a main metering jet likely came loose over the years since the World War II-era craft was restored, the National Transportation Safety Board said. The problem allowed too much fuel to flow, resulting in a loss of engine power.

Ford had just taken off from Santa Monica Airport on March 5 when he reported engine failure at an altitude of 1,100 feet and requested an immediate return.

In an interview with the lead NTSB investigator, Ford “stated that he did not attempt an engine restart but maintained an airspeed of 85 mph and initiated a left turn back toward the airport; however, during the approach, he realized that the airplane was unable to reach the runway. The pilot did not recall anything further about the accident sequence.”

The single-engine Ryan Aeronautical ST-3KR struck a tree and crashed on a golf course about 800 feet from the runway, injuring the actor who was 72 at the time and turned 73 last month. No one on the ground was hurt.

The NTSB found that an improperly installed shoulder harness likely contributed to the severity of Ford’s injuries, which were never detailed.

Ford, who received his pilot’s license in the 1990s, was conscious and able to talk to rescue crews who transported him to a hospital. The actor’s son Ben tweeted just after the crash that his father was “battered” but OK.

The metering jet system is intended to maintain the proper mixture of fuel and air over the engine’s operating speeds, the NTSB said.

A review of maintenance records indicated that the carburetor was rebuilt during the airplane’s restoration about 17 years ago. Contributing to the accident was the lack of adequate instructions on how to maintain the carburetor, the NTSB said.

“Had the carburetor maintenance instruction manual identified a means to ensure the security of the main metering jet, it is unlikely that the jet would have become unseated,” the report said. “There was no record of maintenance personnel inspecting the carburetor jets during the previous 17 years nor was there a requirement to do so.”

The two-seat plane, called the PT-22 Recruit when it was used as a U.S. Army training aircraft, was intentionally designed to mimic the flight characteristics of larger warplanes.

A message seeking comment from a representative for Ford was not immediately returned Thursday.

The actor will reprise his role as Han Solo in the upcoming film “Star Wars: The Force Awakens.”