Report on air accident 10 km north-west of Grimstad, Aust-Agder county, Norway on 21 June 2018 involving Hughes HU 369 D, OH-HNX, operated by Heliwest OY
Aviation report 2019/08 eng
During laser scanning of a power line 21 June 2018, the helicopter main rotor hit a crossing power line. Three conductors on the 132 kV line were cut, but the helicopter made a safe landing at the nearby airport Gullknapp (ENGK).
None of the two persons on-board was injured, and the helicopter was only slightly damaged. However, the accident was very close to becoming a total crash. Several safety barriers failed in connection with the accident and the crew was dependent on detecting the crossing line in time visually to avoid collision. The AIBN believes that a warning sign mounted on the pylons can set up an additional safety barrier and issues a safety recommendation for this.
Safety recommendation
Safety recommendation SL no. 2019/01T
On 21 June 2018 OH-HNX, a helicopter from Heliwest hit a crossing power line and cut all three conductors. The risk of collision with crossing lines is very real in connection with helicopter work at low altitude along power lines. This is e.g. illustrated by the fact that, over a six-month period, Agder Energi Nett had three incidents in connection with work along the company's power distribution network. Sweden and Finland have introduced requirements for physical marking of power lines before they are crossed by overhead cables. The AIBN believes such marking could, to a substantial degree, prevent the risk of collision.
The Accident Investigations Board Norway recommends that the Civil Aviation Authority introduce requirements for physical marking of crossing lines in Norway.
Facts
| Location | Near Grimstad, Aust-Agder County, Norway |
| Occurrence date | 21.06.2018 |
| Aircraft | McDonnell Douglas MD-369 |
| Operator | Heliwest OY, Finland |
| Registration | OH-HNX |
| Meteorological conditions | VMC |
| County | Aust-Agder |
| Type of occurrence | Accident |
| Type of operation | Commercial, other |
| Category of operation | Light, helicopter (<= 2 250kg) |
| Aircraft category | Helicopter, Turboprop/turboshaft |
| FIR/AOR | ENOS (Oslo ATCC) |