Hughes 369 N571HH accident near San Juan, Puerto Rico

Probable cause

The helicopter pilot's improper decision to use an open-end grapple, instead of an A-frame attachment, to lift and move a ladder with a lineman on it and the lineman's improper decision to be lifted on a ladder via an open-end grapple, which were contrary to company policy and the Federal Aviation Regulations.

NTSB analysis

The commercial pilot was conducting helicopter operations to support electrical workers on utility towers. The support included lifting ladders and other equipment with an open-end grapple and lifting ladders with electrical workers (linemen) on them with an A-frame attachment. At the time of the accident, the helicopter was attempting to lift a ladder with a lineman on it using a grapple. The ladder became bound, and the helicopter pilot descended to lower the ladder back on the static arm. The ladder became free of both the grapple and static arm, which resulted in the ladder falling to the ground with the lineman on it, causing a serious injury to the lineman.

Lifting workers with an open-end grapple versus an A-frame attachment was contrary to company policy and Federal Aviation Regulation 27.865(c)(2) because the grapple does not protect against falls. The pilot reported that he was using a grapple at the time of the accident because he thought that he was only lifting the ladder. However, video recorded by the accident lineman earlier that day revealed that the helicopter pilot had previously used a grapple to move a ladder with the lineman on it and that the lineman allowed this situation to happen. Specifically, the video showed the accident lineman giving hand signals to the helicopter pilot while the lineman was on a ladder and then the helicopter lifting the ladder with a grapple so that the ladder could be repositioned to a different location on the utility tower. The pilot and lineman likely continued this practice at the time of the accident. Bee nests at the job site required the linemen to wear bee suits, which might have degraded their ability to clearly communicate, verbally and with head and hand signals, with the helicopter pilot.

Text from the NTSB. Open the NTSB docket for ERA18LA091 for the full record.