Helicopter crash in 1978

This was the second time in just over six months that a helicopter carrying offshore workers had crashed. A machine of the same type was lost on its way to Ekofisk in November 1977, with 12 people killed.

Before that, another helicopter accident had occurred on the way to Ekofisk in 1973 when a Sikorsky made an emergency landing in the sea and four of the 17 people on board died.

The helicopter involved in the 1978 incident belonged to Helikopter Service A/S, and took off from Flesland at 10.25. It was intended to follow the normal route to Statfjord A, with an estimated flight time of 65 minutes and a cruising altitude of 1 000 feet.

Stavanger Radio had the last verbal contact with the machine at 11.06, 36 minutes after take-off. When the crew failed to report at the next checkpoint, several unsuccessful efforts were made to raise them. A Bell 212 helicopter flying the same route out to Statfjord A reported wreckage in the sea 10 minutes later.[REMOVE]Fotnote: Accident Investigation Board Norway. Rapport om luftfartsulykke i Nordsjøen den 26. juni 1978 ca. kl. 1115 med helikopter S-61N LN-OQS: 2.

A rescue operation was launched, and 13 corpses were found floating in the sea along with a good deal of wreckage. A further five bodies and the bulk of the helicopter were later retrieved from a depth of 200 metres.[REMOVE]Fotnote: Accident Investigation Board Norway. Rapport om luftfartsulykke i Nordsjøen den 26. juni 1978 ca. kl. 1115 med helikopter S-61N LN-OQS: 4.

The wreckage was brought ashore and an accident investigation board (AIB) appointed. It was established that the crash had occurred because a main rotor blade broke off the machine as a result of metal fatigue in the spindle connecting it to the rotor hub. Why the fatigue fracture had occurred was unclear.

According to the AIB, “the … material failure in the spindles arose either from changes/faults in the manufacturing process or in maintenance/overhaul methods, or is related to the way the helicopters are used in the widest sense.”[REMOVE]Fotnote: Accident Investigation Board Norway. Rapport om luftfartsulykke i Nordsjøen den 26. juni 1978 ca. kl. 1115 med helikopter S-61N LN-OQS: 43.

The helicopter was not overloaded on its departure from Flesland, and the AIB found that the luggage had been correctly stowed.[REMOVE]Fotnote: Accident Investigation Board Norway. Rapport om luftfartsulykke i Nordsjøen den 26. juni 1978 ca. kl. 1115 med helikopter S-61N LN-OQS: 9. But the overall weight of the helicopter was highlighted in the media as a possible explanation – an increase in the maximum payload had been permitted, and a possible link existed between weight and wear on the rotors. Although no clear answer emerged, the permitted take-off weight was reduced by about 400 kilograms after the accident.[REMOVE]Fotnote: Helgesen, Jan-Petter. Start rotoren. Helikopterets plass i norsk luftfart. Stavanger 1991: 104.

Helikopter Service was the largest operator of such machines for transporting workers on the Norwegian continental shelf (NCS). It had a monopoly until 1977, when Offshore Helicopters A/S was licensed to provide 15 per cent of flights to and from Statfjord.

Questions were asked about the capacity of Helikopter Service to handle its workload, and whether the accident could have been caused by too many flight and emergency landing tests.

A detailed review of the relationship between the volume of flights and the capacity to conduct them was felt to be desirable. More companies might have to be involved to expand capacity and thereby enhance safety.[REMOVE]Fotnote: Aftenposten, 27 June 1978. “Sikkerhetsreglene må vurderes”. Asbjørn Jondal, minister of transport and communications, was sceptical about excessive competition and believed it could have unfortunate aspects.[REMOVE]Fotnote: Rogalands Avis, 27 June 1978. “Ikke ønskelig med konkurranse”.

The remaining Sikorsky machines in the Helikopter Service fleet were inspected in the wake of the accident, and this probably prevented another crash. In one case, cracks were discovered which had propagated through 90 per cent of the material.

This damage had not been spotted by the regular routine inspections. If the helicopter concerned had taken of, it could have crashed on one of its first flights.[REMOVE]Fotnote: Helgesen, Jan-Petter. Start rotoren. Helikopterets plass i norsk luftfart. Stavanger 1991: 105.

No reason was identified for the cracking in the spindle. Sikorsky Aircraft reported that a crash had occurred that May with a similar machine used by the US Coast Guard, which had lost a main rotor blade with attached spindle. These two accidents prompted the manufacturer to develop and make available a new and reinforced spindle type for the S-61N model.[REMOVE]Fotnote: Accident Investigation Board Norway. Rapport om luftfartsulykke i Nordsjøen den 26. juni 1978 ca. kl. 1115 med helikopter S-61N LN-OQS: 15 og 48.

The helicopter accident near Ekofisk in the autumn of 1977 had also been investigated without identifying its cause. No technical faults were ever found on that machine.[REMOVE]Fotnote: Ekofisk industrial heritage. “Et Sikorsky S-61N faller ned”.

Serious debates on the safety of helicopter-borne personnel transport were sparked by these two accidents. The Norwegian Oil and Petrochemical Workers Union (Nopef) wanted a discussion on the mandatory use of survival suits on helicopter flights over the sea. One man had been observed alive in the sea after the Ekofisk crash, but he was wearing neither survival suit nor lifejacket, and failed to keep afloat in the icy water. He had disappeared before rescuers could reach him.

Arguments against wearing survival suits focused on the possibility that their buoyancy could prevent evacuation of a crashed machine. In the water, however, they would both insulate against the cold and keep their wearer afloat.

Such garments were available for all passengers, and most wore them, but this was not mandatory. In addition, lifejackets with signal mechanisms were carried on the helicopters.[REMOVE]Fotnote: Aftenposten, 27 June 1978. “Sikkerhetsreglene må vurderes”.

After the loss of the Alexander L Kielland flotel in March 1980, survival suits finally became mandatory on helicopters.[REMOVE]Fotnote: Ryggvik, Helge, and Marie Smith Solbakken. Norsk oljehistorie. Blod, svette og olje. Oslo 1997: 211.

The people killed in the Statfjord helicopter accident probably died before or immediately after the machine hit the water.

Another wide-ranging discussion concerned the actual use of helicopters to carry personnel to and from facilities in the North Sea. Opportunities for sea transport were investigated, and the Braathens Safe airline went as far as signing a contract to build two high-speed jetfoil vessels which could be available as early as 1981-82.

The company maintained that wind and wave conditions would pose no problems. A trip from the offshore base at Sotra outside Bergen to Statfjord A would take about two hours.[REMOVE]Fotnote: Nytt fra Norge, 1979. “Båttransport istedenfor helikopter i Nordsjøen?”

The people killed in the Statfjord helicopter accident probably died before or immediately after the machine hit the water.

Another wide-ranging discussion concerned the actual use of helicopters to carry personnel to and from facilities in the North Sea. Opportunities for sea transport were investigated, and the Braathens Safe airline went as far as signing a contract to build two high-speed jetfoil vessels which could be available as early as 1981-82.

The company maintained that wind and wave conditions would pose no problems. A trip from the offshore base at Sotra outside Bergen to Statfjord A would take about two hours. The idea was nevertheless dropped and helicopters continued to be used.

The Ministry of Transport and Communications appointed a commission of inquiry into helicopter transport in December 1978, which reported in 1980. This move was prompted not only by the North Sea accidents but also by the development of helicopter flights from a very modest and particular role in the transport picture to a mode of transport of great social significance. The question was whether safety could be improved.

Helicopter flights primarily involved the transport of personnel to and from offshore units. A total of 320 000 passengers were carried in these services during 1977, compared with 350 000 by scheduled flights between Oslo and Bergen.

The commission concluded that statistics on helicopter operations were inadequate and that such data would be required both for planning purposes and as the basis for measures to enhance safety. In addition, coordination between the government agencies concerned needed to improve.[REMOVE]Fotnote: NOU, 1980, 46. Helikoptertrafikken i Nordsjøen / Norwegian Official Report: 46.

Since the 1978 accident, only one helicopter crash with fatalities has occurred involving personnel flights to and from the NCS. A Super Puma machine fell into the sea in 1997 on its way from Brønnøysund to Norne in the Norwegian Sea. Twelve people were killed.

Geir Hamre, head of the operational helicopter department at the Norwegian Civil Aviation Authority, observed in an interview with technical weekly Teknisk Ukeblad that the main reasons for the reduction in accidents were better procedures, improved training at the companies, new helicopter types and enhanced landing procedures.[REMOVE] 

Fotnote: Teknisk Ukeblad, 23 April 2010. “Tryggere å fly helikopter”.

Uptate: In 2016, 13 persons died when an Airbus Helicopters H225 Super Puma lost its rotor and crashed near Turøy, Hordaland. [REMOVE]Fotnote: https://snl.no/Tur%C3%B8y-ulykken