1/26/2012 1:11:00 PM
NEWS BRIEFS
Bolt Blamed for 2010 Helicopter Crash
National Transportation Safety Board agency documents on a 2010 fatal helicopter crash in Texas focus on a standard bolt as the cause.
Reporter Bob Cox of the Fort Worth Star-Telegram wrote that an “improperly manufactured steel bolt that sheared off in flight has been cited as the likely cause of a June 2010 helicopter crash near Midlothian that killed the pilot and mechanic during a routine post-maintenance flight.”
The NTSB final report has not yet been released but a fractured drive pin is the focus in preliminary documents.
The bolt was one of two that anchor the complex mechanism that operates the helicopter’s rotor blades, transmitting the pilot’s flight commands to the blades that control the aircraft.
Bell Helicopter manufactured the drive pins for the Bell model 222 rotor control assembly. Bell has reached out-of-court settlements with the victims’ families.
Bell has sought to collect all the other pins made in 1999 to avoid another crash.
The June 2, 2010, crash happened eight minutes after the helicopter lifted off from Grand Prairie Municipal Airport on a post-maintenance check-out flight. “The investigation and eyewitness accounts showed something had gone terribly wrong with the two-blade main rotor system, which broke off of the aircraft,” according to the Star-Telegram. “The rotor mast broke off in two places, where it attaches to the rotor blades and farther down where it connects to the swashplate, the control mechanism.”
The investigation found the suspect bolt had sheared off in flight, leaving one of the rotor blades uncontrollable. The bolt was one of two made in the same batch in 1999. The second bolt was discarded, but no reason was recorded in required manufacturing records.
NTSB documents show agency investigators working with Bell examined the remaining portion of the sheared bolt and found abnormal, brittle characteristics in the heat-treated, high-strength steel, including pre-existing microscopic cracks, the Star-Telegram reported. The cadmium-coated bolts were made of high-grade steel. If heat treatment is improperly performed, the steel can become brittle and snap rather than bend under stress.
Read more here: http://www.star-telegram.com/2012/01/24/3684883/faulty-bolt-cited-as-likely-cause.html#storylink=cpy
NTSB report
http://media.star-telegram.com/smedia/2012/01/24/16/42/19AIpH.So.58.pdf
National Transportation Safety Board agency documents on a 2010 fatal helicopter crash in Texas focus on a standard bolt as the cause.
Reporter Bob Cox of the Fort Worth Star-Telegram wrote that an “improperly manufactured steel bolt that sheared off in flight has been cited as the likely cause of a June 2010 helicopter crash near Midlothian that killed the pilot and mechanic during a routine post-maintenance flight.”
The NTSB final report has not yet been released but a fractured drive pin is the focus in preliminary documents.
The bolt was one of two that anchor the complex mechanism that operates the helicopter’s rotor blades, transmitting the pilot’s flight commands to the blades that control the aircraft.
Bell Helicopter manufactured the drive pins for the Bell model 222 rotor control assembly. Bell has reached out-of-court settlements with the victims’ families.
Bell has sought to collect all the other pins made in 1999 to avoid another crash.
The June 2, 2010, crash happened eight minutes after the helicopter lifted off from Grand Prairie Municipal Airport on a post-maintenance check-out flight.
“The investigation and eyewitness accounts showed something had gone terribly wrong with the two-blade main rotor system, which broke off of the aircraft,” according to the Star-Telegram. “The rotor mast broke off in two places, where it attaches to the rotor blades and farther down where it connects to the swashplate, the control mechanism.”
The investigation found the suspect bolt had sheared off in flight, leaving one of the rotor blades uncontrollable. The bolt was one of two made in the same batch in 1999. The second bolt was discarded, but no reason was recorded in required manufacturing records.
NTSB documents show agency investigators working with Bell examined the remaining portion of the sheared bolt and found abnormal, brittle characteristics in the heat-treated, high-strength steel, including pre-existing microscopic cracks, the Star-Telegram reported. The cadmium-coated bolts were made of high-grade steel. If heat treatment is improperly performed, the steel can become brittle and snap rather than bend under stress. ©2012 GlobalFastenerNews.com
NTSB report
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