A helicopter crashed at Essex County Airport in Fairfield just after noon on Saturday, injuring the pilot, police said. The chopper crashed into the grass along the Dudak Road side of the airport just before 12:15 p.m. The pilot was reported to be unconscious but breathing and taken to St. Joseph’s Regional Medical Center in Paterson. There were no other injuries reported. The Federal Aviation Administration has been notified and the cause of the crash is under investigation, according to a Fairfield Police dispatcher. A hazardous materials unit from Nutley was at the scene to take care of a f…