Incident Overview
On Saturday, 24 February 2018, at approximately 1335 local time, an Airbus Helicopters AS 350 B3 Ecureuil, registration LN-OWE, operated by Nord Helikopter AS, was involved in a serious incident at Rig Site 13 near Kvamsdal in Masfjorden municipality, Hordaland. The helicopter was conducting commercial cargo flight operations with four persons on board: the pilot-in-command, a loadmaster, and two passengers. No injuries were reported. All three main rotor blades sustained damage, and the container that was struck received minor dents.
Sequence of Events
The helicopter had been supporting foundation work for a new power line pylon. The day before the incident, the crew first flew to the site, located in a cleared power line corridor on a hilltop. The area was assessed as the best available landing site. Later that day, a compressor and equipment container were placed near the landing zone. After work, the container was positioned close to the landing site, to the left and slightly forward of the helicopter. The pilot-in-command judged that he could land with a margin of a few meters between the container and the rotor disc.
The pilot had identified an alternative landing site 30–40 m further along the corridor but it required removal of 3–4 trees and some bushes. On Saturday morning, workers were flown back to the site and the same landing site was used. The pilot used ski marks from the previous landing as reference. Later, a mini-excavator and a load of excavator buckets and a jackhammer were flown in as underslung loads.
In the afternoon, the pilot planned to fly out with two surveyors and bring back the excavator operator. He asked the customer if the new landing site had been cleared. He was told that a chainsaw was taken out in the morning but someone higher in the customer's organization had said it was unnecessary because tracked vehicles would be used, not helicopters. However, later that afternoon the customer requested helicopter transport. The pilot advised that this would be the last flight to the existing landing site and that the new site must be cleared before the next helicopter operation.
The pilot took off from the rig site with the two surveyors and flew 1–2 minutes to the previously used landing site. Since the last landing, the site had changed significantly: it had been dug up and blasted down to bedrock, and equipment for the excavator lay on the ground. The excavator operator was waiting on the left side before the landing site. The pilot focused on finding ski marks from the previous landing, using mirrors and looking forward and to the right while setting down.
The loadmaster had opened the door and was monitoring clearance from the left skid to equipment on the ground. The pilot set the helicopter down, left skid first, then the helicopter tilted to the right before the right skid touched. The pilot considered the helicopter too slanted and unstable for loading/unloading, believing the flat area was more to the left. He gently lifted the helicopter and maneuvered slightly left. He is uncertain how much he communicated this to the loadmaster. As he moved left, he heard a noise and the loadmaster shouted that they had struck the container. The pilot lifted into a hover, moved back to the right, turned 180 degrees, and flew over the slope. At the bottom was an icy lake; about 1 km north were buildings and fields that he considered alternative landing sites, but he was unfamiliar. He felt little vibration and no loss of control, so he returned to the rig site, 1–2 minutes away, and landed without further issues.
Damage
All three main rotor blades were damaged at the tips; the end plate of one blade was torn off. Inspection of the landing site after the incident revealed marks on the container and that the lifting chain was cut. One rotor blade had damage extending far inboard, while the other two did not. Marks from the mini-excavator's teeth were also found on the ground. The pilot believes he may have mistaken these marks for previous ski marks, causing him to land further forward and/or to the left than before.
Investigation Findings
The investigation found that the landing site had changed significantly since the previous landing. The customer and subcontractors had performed excavator work on the site, and physical obstacles were placed such that the site was no longer suitable. The pilot was focused on finding references from the previous landing and had visual control only in mirrors and forward/right. The loadmaster was looking backward and diagonally backward-left. Neither the pilot nor the loadmaster had control of the distance to the container on the left side of the helicopter.