Safety Leader

Up in the Air: Helicopter load classes and line work safety

Class D operations permit the external transport of a person. | J.J. Barber
Class D operations permit the external transport of a person.
J.J. Barber
Published On
Nov 15, 2021

Most people picture lineworkers—whether installing, repairing and maintaining electrical power lines and all subsequent energized and de-energized equipment—in bucket trucks or climbing up poles. When transmission lines or wires are in remote areas or along rough terrain, lineworkers may operate from helicopters. This increases the danger lineworkers face, and it’s important to understand the associated nuances and hazards.

Anyone operating or working from a helicopter must be properly trained and have the necessary certification from the Federal Aviation Administration (FAA) and all other governing bodies. Helicopters can be used to transport workers or materials to a job site. As a result of the low-level aerial nature of the work, many accidents have occurred during helicopter line operations. They range from external workers contacting live lines, to helicopters crashing as a result of rotors tangling in wires, to weight shifting on a load being carried and causing falling objects or an emergency landing.

Helicopters can carry four different load classes per the FAA: A, B, C and D. Class A loads are those that cannot move freely and do not suspend below the helicopter’s landing apparatus. This means that the materials or people are transported in an exterior cargo rack, bin or seat. The seat or area outside the helicopter can also be used as an external work platform.

All external work platforms are required to have a supplemental-type certificate from the FAA. The platform must be designed by a competent person and rigidly attached to the helicopter’s airframe. It must be bonded together and to the aircraft’s frame. The platform is required to be electrically tested for low resistance and free from corona discharge points, where electrical discharge is caused by the ionization of a fluid.

A Class B load is positioned above or below the helicopter skids and can be jettisoned. It is lifted free of land or water with a cargo hook or winch. Placing a commercial transmission tower on the ground with a helicopter would be considered a Class B operation.

Loads that can be jettisoned while a portion of the load remains on the ground are considered Class C operations. This may include stringing lines or dragging poles while suspended from the helicopter.

During stringing operations, measures should be taken to prevent rope slings or steel cables from twisting and ensure all pedestrian and vehicle traffic is clear on the ground. The pilot must be very careful when hooking a line at the base of a tower that is already threaded. Additionally, the sock line should always be pulled sideways so the pilot can see what they’re doing. If a conductor or metal cable is being pulled, always treat it as if it is energized until properly grounded.

Class D operations must be approved on an individual basis through operation specs. This class permits the external transport of a person other than a crew member or a person who is essential to and directly connected with the external-load operation. The personnel lifting device may come in the form of a heli-basket or body harness and must be FAA-­approved. It’s also required to have an emergency release with two distinct actions to achieve release. There must be a guard over the release to prevent the pilot from inadvertently hitting the switch. The pilot and the individual in the personnel lifting device must be in radio contact. Class D loads are not jettisonable.

Lineworkers may be suspended from the helicopter in a Class D operation, from a work platform in Class A operations, or be dropped off and picked up on a pad or at different transmission tower sites. Pilots must adhere to minimum approach distances established by governmental or regulatory entities. They also must be careful not to contact wiring, towers or other equipment with loads or rotors. Often, the pilot won’t be able to see those hazards, but they must know where they are and to avoid them.

Workers should understand grounding and bonding, circuit and fault theory, relaying, breakers and reclosing. They should be well-versed in induction from electric and magnetic fields, as well as testing for potential.

Aerial lineworkers also risk fall hazards during transport to and from structures or towers, electric shock, line tensioning or breaking that causes the helicopter to lose control, and fatigue due to the stressful nature of the work. Lineworkers must be well-rested and focused while working on an operation and use the appropriate fall protection and live-line PPE for the job.

About the Author

Tom O'Connor

Safety Columnist

Tom O'Connor is safety and regulatory affairs manager for Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Reach him at toconnor@intecweb.com.

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