NTSB Identification: CEN09IA618
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Incident occurred Wednesday, July 01, 2009 in Peoria, IL
Probable Cause Approval Date: 11/17/2011
Aircraft: BELL 230, registration: N880SF
Injuries: 4 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
The helicopter pilot observed a caution light for the number one hydraulic system and a corresponding complete loss of hydraulic system pressure for that system. The pilot declared an emergency and performed a run-on landing. A postincident examination of the system's hydraulic pump revealed that two of its cover attachment bolts had separated. The bolt heads fractured in tension from their shanks via intergranular cracks which initiated at the filet radius between the bead and the shank. The bolt fractures exhibited intergranular fracture features over 90 percent of the surface. The operator’s incident report safety recommendation stated that the pump's cover bolts should be replaced at overhaul; however, it is not required. The helicopter had accumulated 269 hours since overhaul.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: The loss of the number one hydraulic system fluid and hydraulic pressure during cruise due to the failure of the bolts that secure the hydraulic pump's cover. Full narrative available
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