Incident Overview
On July 4, 2010, about 0309 eastern daylight time, a Eurocopter AS365N3 helicopter, registration N520CF, operated by Air Methods Corp., experienced an in-flight separation of one of its door windows near Dayton, Ohio. The helicopter was conducting an emergency medical services (EMS) transport flight under 14 CFR Part 135, en route from Lebanon-Warren County Airport (I68) to an automobile accident site near Huber Heights, Ohio. Visual meteorological conditions prevailed. The three occupants—the pilot and two crewmembers—were uninjured. The flight had departed I68 at 0304.
Pilot Statement
According to the operator’s incident report, the pilot stated: at 0304 departed I68 for a scene flight in Huber Heights. Around 0309 local, heard a loud bang. Asked the flight nurse what happened and if she was ok. The flight nurse stated they lost the window and she was ok. At 0310 local, the pilot called the communication center and said they were aborting and landing at Moraine. At 0313 local, the pilot reported safe on deck at Moraine.
Circumstances of Window Separation
The pilot dropped a flight manual during cruise flight. The manual impacted the right front passenger door jettison handle, which was safety wired. However, the handle’s required protective guard was not installed. The jettison handle rotated rearward, broke its safety wire, and disengaged its center door’s upper pin. The center door’s middle and lower pins did not disengage. The window bent outward and separated from its frame. The separated window subsequently impacted the horizontal stabilizer.
Door Jettison System Description
The helicopter’s trainees hand manual describes a door jettisoning system with a handle locked by snap wire and protected by a breakable cover. Actuating the mechanism releases either the studs or the hinge pins. The maintenance manual directs that crew and passenger doors be removed and checked every 600 hours or two years. Reinstallation steps include installing the pneumatic strut, ensuring the handle is against the stop, safing the jettison lever with snap wire, installing the plexiglass protective cover, and checking the locking system and indicator operation.
Maintenance and Modifications
The helicopter was modified with a medical interior under Heli-Dyne Systems Inc. supplemental type certificate SH921NE, field approved by the FAA on January 21, 2005. Airworthiness was maintained under an FAA Approved Aircraft Inspection Program (AAIP). The most recent AAIP inspection, including the jettison handle area, was completed on June 23, 2010. The helicopter’s illustrated parts catalog identifies the Plexiglas jettison handle guard as COVER, JETTISON RH with part number 365A87-3019-87.
Operator Clarification
In a letter to the FAA, the operator stated that confusion arose because the maintenance manual uses reference drawings without the plexiglass protective cover present. Some mechanics believed the decorative plastic trim on the door frame was the guard. The trim installed on N520CF could have been removed and installed in the same sequence in place of the required protective covers.
Manufacturer Response
Subsequent to the incident, the helicopter manufacturer issued Safety Information Notices 2257-S-52 and 2247-S-00. Notice 2257-S-52 described the incident and stressed strict compliance with technical documentation, especially during installation and maintenance. It noted that failure to comply could adversely affect continued airworthiness and flight safety. Notice 2247-S-00 reminded mechanics to strictly follow all applicable maintenance procedures, including basic assembly steps, to ensure proper performance and safety.