EUROCOPTER FRANCE AS350B2SUNDANCE HELICOPTERS INC
Las Vegas, NV, USA · 2011-12-08·N37SH
What happened
NTSB summary, verbatimThe Safety Board’s full report is available at http://www.ntsb.gov/investigations/reports_aviation.html. The Aircraft Accident Report number is NTSB/AAR-13/01. On December 7, 2011, about 1630 Pacific standard time, a Sundance Helicopters, Inc., Eurocopter AS350-B2 helicopter, N37SH, operating as a “Twilight tour” sightseeing trip, crashed in mountainous terrain about 14 miles east of Las Vegas, Nevada. The pilot and four passengers were killed, and the helicopter was destroyed by impact forces and postimpact fire. The helicopter was registered to and operated by Sundance as a scheduled air tour flight under the provisions of 14 Code of Federal Regulations (CFR) Part 135. Visual meteorological conditions with good visibility and dusk light prevailed at the time of the accident, and the flight operated under visual flight rules. The helicopter originated from Las Vegas McCarran International Airport, Las Vegas, Nevada, about 1621 with an intended route of flight to the Hoover Dam area and return to the airport. The helicopter was not equipped, and was not required to be equipped, with any on board recording devices.
Photographs
50the aircraft, and what the investigators foundPhotographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.
Probable cause
the Board's determinationSundance Helicopters’ inadequate maintenance of the helicopter, including (1) the improper reuse of a degraded self-locking nut, (2) the improper or lack of installation of a split pin, and (3) inadequate postmaintenance inspections, which resulted in the in-flight separation of the servo control input rod from the fore/aft servo and rendered the helicopter uncontrollable. Contributing to the improper or lack of installation of the split pin was the mechanic’s fatigue and the lack of clearly delineated maintenance task steps to follow. Contributing to the inadequate postmaintenance inspection was the inspector’s fatigue and the lack of clearly delineated inspection steps to follow.
Occurrence sequence
4 stepsNTSB coding · CICTT taxonomy- 1 · Prior to flightAircraft maintenance event
- 2 · Enroute-cruisePart(s) separation from ACdefining event
- 3 · Enroute-cruiseSys/Comp malf/fail (non-power)
- 4 · Uncontrolled descentCollision with terr/obj (non-CFIT)
Findings
8 causal · 0 contributing- CAUSEAircraft › Aircraft propeller/rotor › Rotorcraft flight control › Rotorcraft servo system — Incorrect service/maintenance
- CAUSEAircraft › Fluids/misc hardware › Misc hardware › Fasteners — Incorrect service/maintenance
- CAUSEPersonnel issues › Task performance › Maintenance › Installation — Maintenance personnel
- CAUSEPersonnel issues › Task performance › Inspection › Post maintenance inspection — Maintenance personnel
- CAUSEAircraft › Aircraft propeller/rotor › Rotorcraft flight control › Rotorcraft servo system — Failure
- CAUSEAircraft › Aircraft oper/perf/capability › Performance/control parameters — Attain/maintain not possible
- CAUSEPersonnel issues › Physical › Alertness/Fatigue — Maintenance personnel
- CAUSEOrganizational issues › Management › Policy/procedure › Availability of policy/proc — Operator
Safety recommendations
3 issuedwhat changed because of this accidentTO THE FEDERAL AVIATION ADMINISTRATION: Establish duty-time regulations for maintenance personnel working under 14 Code of Federal Regulations Parts 121, 135, 145, and 91 Subpart K that take into consideration factors such as start time, workload, shift changes, circadian rhythms, adequate rest time, and other factors shown by recent research, scientific evidence, and current industry experience to affect maintenance crew alertness. (Supersedes Safety Recommendation A-97-71 and A-13-01)
TO THE FEDERAL AVIATION ADMINISTRATION: Encourage operators and manufacturers to develop and implement best practices for conducting maintenance under 14 Code of Federal Regulations Parts 135 and 91 Subpart K, including, but not limited to, the use of work cards for maintenance tasks, especially those involving safety-critical functions, that promote the recording and verification of delineated steps in the task that, if improperly completed, could lead to a loss of control.
TO THE FEDERAL AVIATION ADMINISTRATION: Require that personnel performing maintenance or inspections under 14 Code of Federal Regulations Parts 121, 135, 145, and 91 Subpart K receive initial and recurrent training on human factors affecting maintenance that includes a review of the causes of human error, including fatigue, its effects on performance, and actions individuals can take to prevent the development of fatigue.
NTSB analysis
from the final reportThe Safety Board’s full report is available at http://www.ntsb.gov/investigations/reports_aviation.html. The Aircraft Accident Report number is NTSB/AAR-13/01. On December 7, 2011, about 1630 Pacific standard time, a Sundance Helicopters, Inc., Eurocopter AS350-B2 helicopter, N37SH, operating as a “Twilight tour” sightseeing trip, crashed in mountainous terrain about 14 miles east of Las Vegas, Nevada. The pilot and four passengers were killed, and the helicopter was destroyed by impact forces and postimpact fire. The helicopter was registered to and operated by Sundance as a scheduled air tour flight under the provisions of 14 Code of Federal Regulations (CFR) Part 135. Visual meteorological conditions with good visibility and dusk light prevailed at the time of the accident, and the flight operated under visual flight rules. The helicopter originated from Las Vegas McCarran International Airport, Las Vegas, Nevada, about 1621 with an intended route of flight to the Hoover Dam area and return to the airport. The helicopter was not equipped, and was not required to be equipped, with any on board recording devices.