ERA16LA098

Before takeoff for the positioning flight, the specialty nurse slid closed and latched the left rear door. About 5 minutes after departure, while the helicopter was in cruise flight, the left rear door opened and then separated from the helicopter. The pilot diverted the helicopter to a nearby airport and landed uneventfully. The door was recovered, and postaccident examination revealed that the damage to the door and the airframe was consistent with the damage having incurred during the door's separation from the helicopter. Postaccident examination did not reveal any evidence of preexisting damage of the door frame, door, or door's locking mechanism that would have precluded normal operation. It is likely that the specialty nurse locked the door incorrectly, which resulted in an inadvertent in-flight door opening as the helicopter was traveling 55 knots faster than the manufacturer's specified never-to-exceed speed for operating with the door open, and subsequent separation of the door from the helicopter.

On January 29, 2016, at 1303 eastern standard time, a Eurocopter France EC130 B4, N133HN, operated by Air Methods Corporation, was substantially damaged when the left rear entry door departed the airframe while airborne in the vicinity of Shoals, West Virginia. The commercial pilot and two medical flight crewmembers were not injured. Visual meteorological conditions prevailed. The helicopter was operating on a company visual flight rules flight plan from Cabell Huntington Hospital Heliport (WV27), Huntington, West Virginia, to a helipad at Three Rivers Hospital, Louisa, Kentucky. The positioning flight was conducted under the provisions of 14 Code of Federal Regulations Part 135.According to the pilot, about 5 minutes after takeoff and while in cruise flight at an airspeed of about 125 knots, the he felt and heard an increase of wind in the cockpit. He scanned both front windows to see if they were ajar and, as he faced straight ahead, he heard and felt a rush of air, thinking that the left rear sliding door had opened. As the pilot turned to look, he heard a "whoosh" and saw what he thought was a clipboard depart the helicopter and angle away from the tail. At that point, the pilot slowed the helicopter and instructed the specialty nurse to try and close the door. She seemed to be having some difficulty, so the pilot suggested that the door may have "locked back" and to use the lock release so she could slide the door forward to the closed position. After a few seconds, the specialty nurse announced that the door was missing, and that's when the pilot realized that the clipboard he saw was in fact the door. With no abnormal flight characteristics, the pilot then diverted the helicopter to nearby Tri-State Airport (HTS), Huntington, West Virginia, and landed uneventfully. After shutdown, a visual inspection revealed damage to the left transmission hatch, one rotor blade, and the plastic sliding door guide on the left side baggage door. The flight nurse also noted that she observed the specialty nurse slide and latch the door before takeoff. During the flight, when she heard a loud wind noise, she looked left to see that the door was open. That's when she heard the specialty nurse announce to the pilot that the door was gone. An examination of the helicopter by a Federal Aviation Administration Inspector revealed one of the rotor blades were punctured from the leading edge to the trailing edge. The lower door track exhibited signs of "forced removal" of the attaching hardware. Both upper and lower track lips contained radial damage and missing paint. The middle door track exhibited similar damage. The plastic door stop bracket exhibited impact damage and portion of the stop was missing. An examination of the recovered door revealed the door showed signs of damage along the frame. The door stop was missing from the door and the upper rail arm was loose. The attachment fitting on the arm had chipped paint. The detached left rear passenger door wasrecovered and examined by the airframe manufacturer under the supervision of the NTSB. The door's handle and latching mechanism looked and functioned normally, showed normal wear, and displayed no deformation around the brackets that held the latches or latch pins. According to the helicopter's flight manual, the power on never exceed speed with all doors closed was 155 knots. With the left rear sliding door open and free to move, the never exceed speed decreased to 70 knots. The never exceed was 80 knots with the door locked in the open position and 110 knots with the door removed.