N520CFEurocopter AS365N3 · 1998

On July 26, 2022, at 0455 eastern daylight time, a Eurocopter AS365N3, N520CF, was substantially damaged when it was involved in an accident near Hamilton, Ohio. The pilot and two crew members sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 135 air medical flight.

According to the pilot, he was dispatched to a car accident in Hamilton, Ohio. He checked the weather, approved the flight, and departed for the accident scene around 0428 in dark night visual meteorological conditions. About 9 miles out from the scene, he contacted on-scene fire department personnel, stated that he was a few minutes out, and asked for site information. The fire department personnel reported that there were high voltage power lines on the south side of the landing zone.

As the pilot continued to the scene, he knew the winds were calm and, therefore, he orbited the scene from the south to the north. The pilot made an approach from the south and was looking out for the powerlines but could not locate the wires. The pilot stated that he did not think the wires would be in and around the landing zone. He stated that he was wearing night vision goggles and could see the tower but not the wires. Furthermore, he did not know which way the wires were running off the tower. The pilot used the landing light and moved it up and down to try and find the wires but could not locate them. He thought the wires were further out from the landing zone and not below the helicopter. As the helicopter descended, the main rotor blades contacted the wires and the helicopter fell about 30 to 50 ft. All three crew members egressed after the pilot shut down the engines.

Postaccident examination of the helicopter by a Federal Aviation Administration inspector revealed that the helicopter struck the high voltage wires, severing one wire, and then landed hard. Portions of each main rotor blade were separated near their mid-span, and the main rotor gearbox and mounts were fractured. The left engine was hanging off the engine motor mounts. The helicopter came to rest on its left side with. The stabilizer was bent and substantially damaged, and the landing gear were impact damaged.

On July 4, 2010, about 0309 eastern daylight time, N520CF, a Eurocopter AS365N3 helicopter, operated by Air Methods Corp., sustained minor damage when one of its door windows separated from the helicopter in-flight near Dayton, Ohio. The emergency medical services (EMS) transport flight was conducted under 14 Code of Federal Regulations Part 135, and was en route from the Lebanon-Warren County Airport (I68), near Lebanon, Ohio, to an automobile accident site near Huber Heights, Ohio, when the incident occurred. Visual meteorological conditions prevailed in the area. All three occupants, including the pilot and two crewmembers were uninjured. The flight originated from I68 about 0304.

The pilot, according to an operator’s incident report, in part, stated:

At 0304 departed I68 for a scene flight in Huber Heights. Around 0309 local heard a loud bang. Asked flight nurse what happened and if she was ok. Flight nurse stated we lost the window and she was ok. At 0310 local, I called the communication center and said we were aborting and landing at Moraine. ... At 0313 local, I called safe on deck at Moraine.

The pilot dropped a flight manual during cruise flight. The flight 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.

According to the helicopter’s trainees hand manual, the helicopter is equipped with a door jettisoning system. The system’s description, in part, included:

A handle, locked with snapwire [and] protected by a breakable cover, makes it possible, should it be necessary, to jettison the doors. Actuating the mechanism releases either the studs or the hinge pins.

The helicopter’s maintenance manual directs that the crew and passenger doors be removed and checked every 600 hours of flight time or every two years. The manual, in part, lists the following steps to reinstall the doors.

- Install the pneumatic strut and check for correct engagement of the ball-joints.

- Make sure that handle is against stop, then safety jettison lever with snap wire.

- Install the plexiglass protective cover.

- Safety and lock the door and check:

- the locking system is correctly engaged,

- the indicating system operation.

A Heli-Dyne Systems Inc. supplemental type certificate, SH921NE, was the basis on which the helicopter was modified to install a medical interior. Airworthiness documents showed that this major alteration was field approved by the Federal Aviation Administration(FAA) on January 21, 2005.

The helicopter's airworthiness was maintained under a FAA Approved Aircraft Inspection Program (AAIP). The helicopter's most recent AAIP inspection, to include the area of the jettison handle, was completed on June 23, 2010.

The helicopter’s illustrated parts catalog identified the Plexiglas jettison handle guard as COVER, JETTISON RH with part number 365A87-3019-87.

In a letter to the FAA, the operator, in part, stated:

Confusion sets in when [the maintenance manual] uses reference drawings with no "Plexiglas Protective Cover" present. It was believed by the questioned mechanics that the 14 [degree] frame decorative plastic trim was the guard; the decorative plastic trim installed on N520CF could have been removed and installed in the same sequence in place of the “Plexiglas Protective Covers” called out in [the maintenance manual]

Subsequent to the accident, the helicopter manufacturer issued Safety Information Notice 2257-S-52 and 2247-S-00. Notice 2257-S-52 described the incident and, in part, stated:

Considering that the in-flight loss of an aircraft component can seriously affect the safety of the flight and/or of the persons on the ground, EUROCOPTER reminds you that the content of the technical documentation issued by EUROCOPTER must be strictly complied with, especially regarding the installation of aircraft components during removal/installation or maintenance operations. Any failure to comply with any rules specified in the EUROCOPTER technical documentation may adversely affect the aircraft continued airworthiness and flight safety. We also recommend you to read the Safety Information Notice 2247-S-00, which covers specifically serious accidents/incidents caused by failures in the basic application of maintenance instructions.

Notice 2247-S-00 indicated that it was a reminder to mechanics that while performing ‘routine’ applicable maintenance procedures, in particular assembly procedures, “it is important to strictly comply with all applicable maintenance procedures, including the most basic and simple ones, to ensure proper helicopter performance and flight safety.”