Bell 407 In-Flight Tail Boom Separation
Notice Number: NOTC2727

This message is intended to broaden the awareness to owners and operators of information related to a helicopter accident recently shared with the public by the NTSB. To explore the NTSB’s information in more depth, the NTSB’s public docket and preliminary report on the accident are the best resources. Likewise, the FAA’s airworthiness directive from 2012 noted in this message is available at https://drs.faa.gov/.

On October 31, 2022, the NTSB publicly released the docket (https://data.ntsb.gov/Docket?ProjectID=105233) for a Bell 407 helicopter accident that occurred on June 8, 2022 to N402SH (NTSB number: ANC22FA041). The accident occurred during a Part 135 on-demand air tour flight in Hawaii. Serious injuries were reported to three of the six occupants. According to the NTSB’s preliminary report, the helicopter was at 500-600 feet AGL between airspeeds of 122 and 127 knots. About 30 minutes into the flight, the pilot reported a violent upset occurred followed by an uncontrolled spin (yaw) to the right. The helicopter impacted an area of rough, uneven lava-covered terrain.

The NTSB’s preliminary report notes the tail boom separated from the fuselage at the point where the two attach. The tail boom of the helicopter came to rest about 762 feet northeast from the main wreckage. The upper left attachment fitting fastener (part of the tail boom attachment hardware) was not present and not located.

The requirements in FAA Airworthiness Directive (AD) 2012-18-09 address the Bell 407’s tail boom attachment hardware. The AD was effective October 22, 2012 and one of the requirements is a recurring torque check of the Bell 407’s tail boom attachment fasteners (nuts) at an interval not to exceed 300 hours time in service. The NTSB’s preliminary report noted that the most recent tail boom attachment fastener torque check for the Bell 407 involved in the accident was completed on May 4, 2022. The report also noted that 114.2 flight hours occurred between the May 4, 2022 torque check and the June 8, 2022 accident.

As noted in the NTSB docket on page 18 of the Airworthiness Group Chair’s Factual Report, “As a result of this accident, the operator elected to replace the tail boom attachment hardware on their remaining five Bell 407 helicopters as a precautionary measure. At the request of the NTSB, the operator performed a torque check of all installed attachment hardware prior to their removal. The operator reported no evidence of loose tail boom attachment hardware on their remaining Bell 407 helicopters.” The Airworthiness Group Chair’s Factual Report goes on to discuss the operator’s additional precautionary measure of eddy-current nondestructive inspection (NDI) on the aft fuselage longerons (to which the tail boom attaches).

The NTSB’s investigation of this event is ongoing. The investigation has included communication with Transport Canada, the government organization with the primary state of design responsibility for airworthiness and continued operational safety of the Bell 407. Likewise, the investigation has included communication with Bell Textron Canada Limited as the original equipment manufacturer (OEM) of the Bell 407 and the FAA as the government organization that is the state of occurrence of the accident and the state of registry for the helicopter. As the investigation progresses, the FAA will continue coordinating with the NTSB, Transport Canada, and Bell Textron Canada Limited as the FAA determines if any mandatory airworthiness action is warranted.

Point of Contact: Kristin Bradley, AIR-723, Kristin.Bradley@faa.gov