(NSI News Source Info) March 21, 2009: The Transportation Safety Board (TSB) of Canada says the U.S. Federal Aviation Administration intends to order all operators of the Sikorsky S-92A helicopter to ground their aircraft so that steel replacements can be installed for the main gearbox filter bowl assembly mounting stud, according to a March 20 TSB press release. 
The S-92 is a twin turbine engined utility helicopter with aluminium airframe with some composite components. The four-bladed fully articulated composite main rotor blade is wider and has a longer radius than the S-70 Blackhawk. The tapered blade tip sweeps back and angles downward to reduce noise and increase lift. Tethered hover flight has recorded 31,000 lb of lift generated, both in and out of ground effect.
A number of safety features such as flaw tolerance, bird strike capability, and engine burst containment have been incorporated into the design. Adherence to FAA FAR part 29 has led the FAA certification board to call the S-92 the "safest helicopter in the world". An active vibration system using structurally mounted force generators ensures comfortable flight and acoustic levels which are well below certification requirements. These systems also prolong the life of the airframe by reducing fatigue loads on the aircraft.
But FAA spokesman Les Dorr said that was not necessarily the case. Dorr said the U.S. agency was only considering "issuing an airworthiness directive that would cover an issue uncovered in the investigation."
TSB officials recently began examining the wreckage of an S-92 that went down off the coast of Newfoundland on March 12.
On Jan. 28, Sikorsky issued a bulletin to S-92 operators indicating that the titanium studs should be replaced with steel ones. This one-time modification was to be accomplished within one year or 1,250 flight hours, whichever occurred first.
The S-92 is a twin turbine engined utility helicopter with aluminium airframe with some composite components. The four-bladed fully articulated composite main rotor blade is wider and has a longer radius than the S-70 Blackhawk. The tapered blade tip sweeps back and angles downward to reduce noise and increase lift. Tethered hover flight has recorded 31,000 lb of lift generated, both in and out of ground effect.
A number of safety features such as flaw tolerance, bird strike capability, and engine burst containment have been incorporated into the design. Adherence to FAA FAR part 29 has led the FAA certification board to call the S-92 the "safest helicopter in the world". An active vibration system using structurally mounted force generators ensures comfortable flight and acoustic levels which are well below certification requirements. These systems also prolong the life of the airframe by reducing fatigue loads on the aircraft.
But FAA spokesman Les Dorr said that was not necessarily the case. Dorr said the U.S. agency was only considering "issuing an airworthiness directive that would cover an issue uncovered in the investigation."
TSB officials recently began examining the wreckage of an S-92 that went down off the coast of Newfoundland on March 12.
On Jan. 28, Sikorsky issued a bulletin to S-92 operators indicating that the titanium studs should be replaced with steel ones. This one-time modification was to be accomplished within one year or 1,250 flight hours, whichever occurred first.
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