Heliport
7th Aug 2003, 16:45
from the Guardian A helicopter carrying oil workers from a North sea oil rig suffered serious damage to its tail rotor after being pitched about by a giant waterspout off the Shetland Islands, accident investigators have reported.
The Super Puma helicopter, with 18 people on board, was flying at 500ft in February last year when it encountered a vortex of air, the result of a miniature tornado, which caused seawater to shoot into the clouds.
An official report by accident investigators revealed that the pilot had left the engine on autopilot. When it reached the spout the helicopter "violently pitched, rolled and yawed".
The change in direction was so fast that all five of the tail rotors touched the tail pylon, leaving a 15cm gash which was later discovered by engineers.
An on-board flight recorder showed the helicopter had rolled 9.5 degrees to the right then 34 degrees to the left within two seconds, with the nose pitching sharply down.
The incident was far more severe than the helicopter was required to withstand for certification. The 51-year-old captain was quickly able to regain control and made an announcement to reassure shaken passengers on the helicopter's public address system.
A spokesman for Bristow Helicopters, which owns the aircraft, said: "Waterspouts aren't that unusual around the coast, but actually flying into one is. In this case there was nothing the pilots could do to avoid it."
The flight was ferrying staff from Shell's Dunlin Alpha oil platform to the remote Scatsta airfield, 24 miles north of Lerwick.
and
from The Scotsman EIGHTEEN helicopter passengers experienced violent pitching, rolling and turning after their aircraft encountered a waterspout, an official accident report said yesterday.
A huge gust caused the aircraft to climb about 200ft and turn to the right while significantly losing speed as the two pilots tried, and eventually managed, to regain control.
The incident, which damaged all five tail rotor blades, was far more severe than the helicopter was meant to withstand.
The crew was able to land the Super Puma helicopter, which was flying from a North Sea drilling platform, safely in the Shetland Islands.
After the incident on the morning of 28 February, 2002, the captain spoke to the passengers on the public address system to explain what had occurred and to reassure them that the aircraft, owned by Bristow Helicopters, was safe.
A waterspout is like a tornado at sea, in which a continuous vortex can extend from a cloud all the way down to the surface of the water.
The report from the Air Accidents Investigation Branch (AAIB) said: "There is little doubt that G-TIGB [the helicopter] was subjected to a violent upset from a gust, estimated to have been in the region of 40 knots, as a result of encountering significant atmospheric disturbance in the vicinity of a water- spout."
The AAIB added that the crew had made every effort to avoid the bad weather and that the effects of the waterspout had occurred within seconds of the captain sighting the disturbance on the surface of the water.
The report added that a new standard of tail rotor blade on the helicopter was considered "to have contributed significantly to the helicopter’s ability to continue flight after the blades sustained serious damage".
To read the AAIB Report click on the photograph.
http://home.quicknet.nl/qn/prive/roest/pictures/gtigb.jpg (http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafety_023429.hcsp)
The Super Puma helicopter, with 18 people on board, was flying at 500ft in February last year when it encountered a vortex of air, the result of a miniature tornado, which caused seawater to shoot into the clouds.
An official report by accident investigators revealed that the pilot had left the engine on autopilot. When it reached the spout the helicopter "violently pitched, rolled and yawed".
The change in direction was so fast that all five of the tail rotors touched the tail pylon, leaving a 15cm gash which was later discovered by engineers.
An on-board flight recorder showed the helicopter had rolled 9.5 degrees to the right then 34 degrees to the left within two seconds, with the nose pitching sharply down.
The incident was far more severe than the helicopter was required to withstand for certification. The 51-year-old captain was quickly able to regain control and made an announcement to reassure shaken passengers on the helicopter's public address system.
A spokesman for Bristow Helicopters, which owns the aircraft, said: "Waterspouts aren't that unusual around the coast, but actually flying into one is. In this case there was nothing the pilots could do to avoid it."
The flight was ferrying staff from Shell's Dunlin Alpha oil platform to the remote Scatsta airfield, 24 miles north of Lerwick.
and
from The Scotsman EIGHTEEN helicopter passengers experienced violent pitching, rolling and turning after their aircraft encountered a waterspout, an official accident report said yesterday.
A huge gust caused the aircraft to climb about 200ft and turn to the right while significantly losing speed as the two pilots tried, and eventually managed, to regain control.
The incident, which damaged all five tail rotor blades, was far more severe than the helicopter was meant to withstand.
The crew was able to land the Super Puma helicopter, which was flying from a North Sea drilling platform, safely in the Shetland Islands.
After the incident on the morning of 28 February, 2002, the captain spoke to the passengers on the public address system to explain what had occurred and to reassure them that the aircraft, owned by Bristow Helicopters, was safe.
A waterspout is like a tornado at sea, in which a continuous vortex can extend from a cloud all the way down to the surface of the water.
The report from the Air Accidents Investigation Branch (AAIB) said: "There is little doubt that G-TIGB [the helicopter] was subjected to a violent upset from a gust, estimated to have been in the region of 40 knots, as a result of encountering significant atmospheric disturbance in the vicinity of a water- spout."
The AAIB added that the crew had made every effort to avoid the bad weather and that the effects of the waterspout had occurred within seconds of the captain sighting the disturbance on the surface of the water.
The report added that a new standard of tail rotor blade on the helicopter was considered "to have contributed significantly to the helicopter’s ability to continue flight after the blades sustained serious damage".
To read the AAIB Report click on the photograph.
http://home.quicknet.nl/qn/prive/roest/pictures/gtigb.jpg (http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafety_023429.hcsp)