A pilot flying in the north suburbs crashed his private plane in July because he flew too fast and ran out of fuel, according to a government investigation.

The 74-year-old man was piloting a two-seater, amphibious plane alone on July 11 from Indianapolis when he lost power and was forced to land about a mile from the Chicago Executive Airport in Wheeling, according to a preliminary report from the National Transportation Safety Board.

He crashed into trees in a forest preserve about 8:52 p.m. — causing extensive damage to the aircraft — but walked away unscathed, authorities said at the time.

His wife, who was flying along side him in an identical Icon Aircraft A5, was able to land at the airport with over a gallon of fuel in her tank, according to the report.

A preliminary investigation shows the pilot miscalculated the amount of fuel needed for the 190 mile trip from Eagle Creek Airport in Indianapolis to Chicago Executive Airport.

Data showed the pilot pushed the limits of the aircraft and flew at full-throttle for the majority of the 2.5 hour trip, according to the report. That was far above the 5-minute limit of full-throttle flight recommended by the aircraft’s owners manual.

The pilot calculated the flight would require 13 gallons of fuel, and had loaded up with that and four gallons extra, the report states. But the fueling formula assumes the plane will be flown at a recommended cruising speed.

The pilot reported that the first two hours of his flight was uneventful until he was 3 miles out from Chicago Executive Airport, the report states. The engine began to lose power due to lack of fuel, and the pilot was forced to land in the forest preserve.

The NTSB tested the fuel tank of the crashed plane and found the fuel gauge overestimated the amount of fuel in the tank by over a gallon, the report states.

The NTSB’s investigation is ongoing and may not be complete for another 11 to 23 months, an NTSB spokesman said. The Federal Aviation Administration, which handles disciplinary action against pilots, is awaiting results of the investigation, an FAA spokesperson said.

Spokespeople for both federal agencies declined to speak about details of the crash or the pilot.