What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
The part 135 flight departed from juneau on 18MAY2018 at 12:51 AKDT to service a us coast guard radio facility on the 2200' level deception hills located near the coast 58 miles southeast of Yakutat Alaska. Weather was derived from NWS, METAR, TAF reports for, cape spencer, Yakutat , and juneau. FAA cams and area forecast maps were also consulted.
En route weather was clear with a tailwind from the east/souteast that averaged 15 knots. Mechanical turbulence through the fairweather range was less than expected.
Landing deception hills main pad ~1400 AKDT. During recon noted a consistent wind from se in vicinity of 25 KTS. Per briefing landed into wind with tail pointed towards Yakutat and shutdown. Also noted per briefing the steep terrain on both se and nw sides of the pad.
Noticed a marine/cumulus layer blowing up the coastline and inland and warned passengers we might need to depart sooner than the requested hour standby. At 14:45 observed clouds invading nearby ridges and told passengers to collect gear and loaded gear and passengers. Wind was the same as landing with some gusts (25G30) coming through every few minutes in front of cloud front.
Pre-start checklist. Noted ASI needle was moving between zero and first mark (20 KTS) in conjunction with wind. Commenced start. As T4 had "second" light off and with blades moving slowly felt/heard a stronger gust and a loud bang almost simultaneously. Helicopter also lurched to the right ~5 degrees. Immediately aborted start and applied full rotor brake to stop blades. Visually inspected a dent in the tr driveshaft cowling on the starboard side of helicopter. Wind gusts continued to pick up. Called base on sat phone (1500) and enlisted passenger help in tying down all blades.
As the FAA filed it
THE PART 135 FLIGHT DEPARTED FROM JUNEAU ON 18MAY2018 AT 12:51 AKDT TO SERVICE A US COAST GUARD RADIO FACILITY ON THE 2200' LEVEL DECEPTION HILLS LOCATED NEAR THE COAST 58 MILES SOUTHEAST OF YAKUTAT ALASKA. WEATHER WAS DERIVED FROM NWS, METAR, TAF REPORTS FOR, CAPE SPENCER, YAKUTAT , AND JUNEAU. FAA CAMS AND AREA FORECAST MAPS WERE ALSO CONSULTED.
EN ROUTE WEATHER WAS CLEAR WITH A TAILWIND FROM THE EAST/SOUTEAST THAT AVERAGED 15 KNOTS. MECHANICAL TURBULENCE THROUGH THE FAIRWEATHER RANGE WAS LESS THAN EXPECTED.
LANDING DECEPTION HILLS MAIN PAD ~1400 AKDT. DURING RECON NOTED A CONSISTENT WIND FROM SE IN VICINITY OF 25 KTS. PER BRIEFING LANDED INTO WIND WITH TAIL POINTED TOWARDS YAKUTAT AND SHUTDOWN. ALSO NOTED PER BRIEFING THE STEEP TERRAIN ON BOTH SE AND NW SIDES OF THE PAD.
NOTICED A MARINE/CUMULUS LAYER BLOWING UP THE COASTLINE AND INLAND AND WARNED PASSENGERS WE MIGHT NEED TO DEPART SOONER THAN THE REQUESTED HOUR STANDBY. AT 14:45 OBSERVED CLOUDS INVADING NEARBY RIDGES AND TOLD PASSENGERS TO COLLECT GEAR AND LOADED GEAR AND PASSENGERS. WIND WAS THE SAME AS LANDING WITH SOME GUSTS (25G30) COMING THROUGH EVERY FEW MINUTES IN FRONT OF CLOUD FRONT.
PRE-START CHECKLIST. NOTED ASI NEEDLE WAS MOVING BETWEEN ZERO AND FIRST MARK (20 KTS) IN CONJUNCTION WITH WIND. COMMENCED START. AS T4 HAD "SECOND" LIGHT OFF AND WITH BLADES MOVING SLOWLY FELT/HEARD A STRONGER GUST AND A LOUD BANG ALMOST SIMULTANEOUSLY. HELICOPTER ALSO LURCHED TO THE RIGHT ~5 DEGREES. IMMEDIATELY ABORTED START AND APPLIED FULL ROTOR BRAKE TO STOP BLADES. VISUALLY INSPECTED A DENT IN THE TR DRIVESHAFT COWLING ON THE STARBOARD SIDE OF HELICOPTER. WIND GUSTS CONTINUED TO PICK UP. CALLED BASE ON SAT PHONE (1500) AND ENLISTED PASSENGER HELP IN TYING DOWN ALL BLADES.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.
Other reports on N288CH · 1
Matched to the same aircraft by N-number and date.