NTSB Factual Report

On August 19, 2018, about 1320 Hawaii-Aleutian standard time, a Eurocopter EC-130 B4 helicopter, N11QP, experienced an in-flight separation of its left rear sliding door during cruise flight near Hilo, Hawaii. The airline transport pilot was not injured, and the sole passenger sustained minor injuries. The helicopter sustained substantial damage to the main rotor blades. The helicopter was registered to Nevada Helicopter Leasing LLC. and operated by Helicopter Consultants of Maui Inc. as a Title 14 Code of Federal Regulations Part 91 maintenance flight. Visual meteorological conditions were reported along the route of flight about the time of the accident and a company flight plan was filed. The local flight originated from Hilo International Airport (ITO), Hilo, Hawaii about 1310.

According to the pilot, he was tasked to perform a maintenance flight for track and balance of the main rotor blades. He had flown a previous flight in the helicopter but ended it early due to mechanical issues with the track and balance equipment.

After the mechanical issues were fixed, the pilot and maintenance personnel departed ITO to complete the track and balance maintenance flight.

After completion of the second flight and while enroute back to ITO, the pilot reported that he heard the left-rear sliding door open. He looked over his left shoulder and saw the left-rear sliding door had departed the helicopter. He turned his head forward then heard a loud noise and felt a "jolt". He added that, the helicopter began to vibrate but remained controllable. The pilot elected to perform a precautionary landing onto a grass field.

The helicopter was secured in the operator's hanger for further examination.