Bell OH 58C N139RD

Summary

On 1 November 2016 at about 15:30 local time, a Bell OH 58C registered N139RD, operated by Helicopter Applicators Inc, was involved in an accident near Cameron, North Carolina, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

1 November 2016 at 15:30

Classification

Accident

Location

Cameron, North Carolina, United States

Coordinates

35.3508, -79.2958

Aircraft

Bell OH 58C

Registration

N139RD

Category

Helicopter

Year built

1971

Engines

1

Operator

Helicopter Applicators Inc

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Cameron → Cameron

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA17LA032

1 person had minor injuries.

An in-flight failure of a main rotor blade due to fatigue cracks. Contributing to the failure of the main rotor blade was the absence of guidance to the operator to inspect an area of the main rotor blade known to be susceptible to fatigue cracks and the accident helicopter type certificate holder’s lack of information of an existing inspection published by another restricted-category type certificate holder of the same model helicopter.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The commercial pilot was conducting a local aerial application flight in the restricted-category military surplus helicopter. After loading the helicopter with herbicide, the pilot departed from the staging area; however, during the initial climb, as the helicopter was about 50 ft above the ground, the outboard portion of one of the two main rotor blades separated. The main rotor blades then struck the tailboom, and the helicopter entered an uncontrolled descent to the ground. Metallurgical examination of the fractured main rotor blade revealed a crack with fatigue features emanating from multiple origins in the area of the inertia weight attachment hole. The helicopter manufacturer, Bell, also a restricted-category type certificate holder for the same model helicopter as the accident helicopter, had published a military alert bulletin (MAB) about 30 years before the accident (revised about 9 years before the accident) and an operations safety notice (OSN) about 9 years before the accident applicable to the main rotor blade that fractured during the accident flight; operators were instructed to conduct initial visual inspections of the blades in the area of the inertia weight screw heads and subsequent inspections at intervals of 8 hours or 32 flights, whichever occurred first. However, the OSN only applied to the airframe serial numbers under the responsibility of Bell. Both the operator and the type certificate holder of the accident helicopter, Rotorcraft Development, indicated that they were not aware of the MAB or the OSN until after the accident. Additionally, a preventive maintenance services inspection program that was published by the previous type certificate holder for the accident helicopter (Garlick Helicopters) did not contain requirements to inspect the main rotor blade per the aforementioned MAB and OSN. Performance of the recurrent inspection required by the MAB and the OSN likely would have detected the fatigue cracks on the main rotor blade before its failure during the accident flight. The Federal Aviation Administration did not require sharing of safety information, such as the MAB and the OSN recurrent inspections, between restricted-category type certificate holders.

Quoted verbatim from the NTSB record.