On Tuesday, the NTSB faulted maintenance performance and procedures at Las Vegas, Nev.-based air-tour operator Sundance Helicopters as the probable cause of the Dec. 7, 2011 crash of an AS350B2 that killed the pilot and four passengers near the Hoover Dam. The 1988 helicopter was originally manufactured as an AS350B and had accumulated 25,216 hours since new. Total time on the rental engine was 7,400 hours.
The helicopter had been returned to service earlier on the day of the crash following major maintenance that included an engine change and replacement of main- and tail-rotor actuators. NTSB investigators evaluating the wreckage identified that the fore/aft servo input rod was not connected to the fore/aft servo and that connecting hardware was missing.
The NTSB found that Sundance improperly used a degraded self-locking nut on the input rod, improperly installed or failed to install a split pin through the nut and conducted inadequate post-maintenance inspections, which resulted in the in-flight separation of the servo control input rod and rendered the helicopter uncontrollable. Maintenance technician and inspector fatigue were contributing factors, the NTSB said.
Nationwide helicopter EMS operator Air Methods bought the assets of Sundance in December.