| Helikopter Service Flight 165 | |
| Occurrence Type: | Accident |
| Date: | 26 June 1978 |
| Type: | Structural failure |
| Site: | North Sea, Norway |
| Coordinates: | 61.0167°N 50°W |
| Aircraft Type: | Sikorsky S-61 |
| Operator: | Helikopter Service |
| Tail Number: | LN-OQS |
| Origin: | Bergen Airport, Flesland, Bergen, Norway |
| Destination: | Statfjord A, North Sea, Norway |
| Passengers: | 16 |
| Crew: | 2 |
| Fatalities: | 18 |
| Survivors: | 0 |
Helikopter Service Flight 165 was a crash of a Sikorsky S-61 helicopter into the North Sea, northwest of Bergen, Norway, on 26 June 1978. The aircraft was en route from Bergen Airport, Flesland to Statfjord A, an offshore oil platform. The accident was caused by a fatigue crack in a knuckle joint, causing one of the rotor blades to loosen. All eighteen people on board were killed in the crash.[1]