Incident Overview
On January 11, 2018, about 1350 Atlantic Standard Time, a Hughes 369D (registration N571HH) operated by High Line Helicopters LLC (HLH) was not damaged during an external load operation near San Juan, Puerto Rico. The commercial pilot was not injured, while one power line maintenance person was seriously injured. The flight was conducted under Title 14 Code of Federal Regulations Part 133 in visual meteorological conditions. No flight plan was filed.
Sequence of Events
The day's work involved installing polymer insulators and wire to utility towers. The pilot used the helicopter to lift ladders with ground crewmen nine times using an A-frame attachment at the end of the longline. After moving a wire with a grapple and 100-foot longline, a radio transmission requested a ladder pick using the grapple. The pilot saw two linemen on the tower. He positioned the helicopter to pick up the ladder. After receiving a visual signal from the upper lineman, the pilot applied upward pressure. The ladder became bound, and both linemen shook it to free it. The upper lineman reached for the right-side safety chain; the ladder pivoted, came free, and the lineman and ladder fell.
According to the pilot's statement, after the ladder became bound, the upper lineman signaled to lower the line. The pilot lowered until the grapple was free. As the linemen shook the ladder, the upper one reached for the safety chain, and the ladder pivoted and fell.
The accident lineman reported that a conductor was positioned low and hard against the tower, requiring a longer line. The pilot radioed he would try again with a shorter line. The lineman wanted to move the ladder to the other side. The helicopter returned with the A-frame and moved the ladder with the lineman on it, but not to the desired location. Later, the helicopter used the grapple to move the ladder with the lineman to the other side successfully. Subsequently, the pilot tried to lift the ladder with the lineman on it using the grapple before the lineman had unsafetied the ladder from the tower. After the lineman disconnected the safety, the ladder tipped and both fell.
Another lineman reported that earlier in the day they had used the grapple to move the ladder with the accident lineman on it, which he noted was surprising. The accident lineman had told the pilot he needed the ladder further away; the pilot used the grapple instead of the A-frame.
Review of videos showed the helicopter lifting a cable with a grapple 40 minutes prior, and lifting a ladder with a lineman using an A-frame 20 minutes prior. Another video showed the accident lineman being lifted with a grapple earlier that day.
Investigation Findings
The U.S. Army Corps of Engineers (USACE) accident report stated the direct cause was: "Failure to follow written safety procedures… Grapple hook was used instead of A Frame which is approved for human transport. This does not follow flight rules for human transport or the written safety policies in company safety manual."
The electrical contractor accident report stated the direct cause was: "…The individual's failure to follow the written procedures for the transport of human cargo by both the helicopter pilot and both lineman resulted in Lineman 1's fall from the helicopter. The use of a grapple hook for human external cargo (HEC) is not allowed in the (HLH) safety manual. Lineman 2 observed this procedure being violated while working on the first pole but did not stop the work. Lineman 1 and (the pilot) both violated this procedure at least two times on poles 1 and 2."
Both linemen were wearing bee suits due to bee nests; neither had previously performed this work wearing a bee suit.
The investigation referenced Federal Aviation Regulation 27.865(c)(2) and (4), which require approved personnel-carrying devices and intercommunication equipment for human external cargo operations.
Weather at 1356 at Luis Munoz Marin International Airport, about 15 nautical miles northwest, included wind at 17 knots gusting 23 knots, temperature 29°C, dew point 21°C.