FAA issues d-ring reversal guidelines
FAA has released a Safety Alert for Operators for rescue helicopter crews on the possibility of d-ring reversal or dynamic rollout during winching and longline operations.
The Federal Aviation Administration (FAA) has released a Safety Alert for Operators (SAFO) for rescue helicopter crews on the possibility of d-ring reversal or dynamic rollout during winching and longline operations.
The SAFO states: “D-ring reversal has directly contributed to several fatal accidents. This phenomenon can be described as the unintended release of the primary engaging ring from the winch hook that may occur subsequent to a pause in the winching sequence.”
It continues: “When the ring in the rescue strap and the hook are temporarily relieved of the load, a dynamic condition exists allowing the ring to travel up and flip over the tip of the hook and come to rest on the spring-loaded keeper. The ring is now only supported by the spring-loaded keeper. When the load is re-applied, the ring is forced open and the spring-loaded keeper allows the ring to fall free from the hook.”
The FAA recommended a number of actions in order to try and stop this event from occurring, including using only rescue hooks with a mechanical locking keeper or guards, ensuring initial and recurrent winch operational training is tailored for each helicopter type and winch combination, and developing ‘procedures which list the specific d-rings or equipment which may be attached to a specific rescue hook wherein the possibility of d-ring reversal is physically impossible’.