ASN Wikibase Occurrence # 292264
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| Date: | Monday 29 May 2006 |
| Time: | 14:00 LT |
| Type: |  Eurocopter AS-350BA |
| Owner/operator: | Montel Equipment Minier Inc. |
| Registration: | C-GGLM |
| MSN: | 1306 |
| Year of manufacture: | 1980 |
| Total airframe hrs: | 6783 hours |
| Engine model: | Honeywell LTS 101 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Goshen, New York -
 United States of America
|
| Phase: | Unknown |
| Nature: | Private |
| Departure airport: | Camden, NJ (19N) |
| Glen Falls, NY | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
About 45 minutes into a cross-country flight, the helicopter experienced a hydraulic system failure. The pilot subsequently elected to perform a precautionary landing in a field. During the landing attempt, the pilot slowed the helicopter and it began to yaw left. The pilot attempted to correct the yaw, but was unable to overcome the "stiffness" of the right anti-torque pedal. The helicopter continued to yaw left, landed "hard," and rolled over. Examination of the helicopter's hydraulic system revealed that the hydraulic pump drive shaft splines and the attaching drive coupling splines were severely worn, to the point that they could no longer drive the hydraulic pump. Metallurgical hardness testing of both the drive shaft and the coupling revealed that the surfaces of the splines were below the manufacturer's specified hardness. Examination of the grease found trapped between the remaining portions of the hydraulic shaft pump splines revealed that it was hard packed and gray colored, suggesting that it had been in place for a significant period of time. The minimal amount of grease observed in the coupling sleeve did not satisfy the "generously filled" description referred to in the manufacturer's service bulletin, and required by a subsequent airworthiness directive. Examination of the helicopter's maintenance records revealed that since the issuance of the airworthiness directive, the helicopter had not been in compliance with either the calendar or flight time requirements. The helicopter's flight manual cautioned pilots operating the helicopter without hydraulic assistance, "Do not attempt to carry out hover flight or any low speed maneuver. The intensity and direction of the control feedback forces will change rapidly. This will result in excessive pilot workload, poor aircraft control, and possible loss of control."
Probable Cause: Improper maintenance of the hydraulic pump/coupling, which resulted in a failure of the hydraulic flight control system. Factors included the substandard materials of the hydraulic pump drive shaft and coupling, and the pilot's failure to maintain an adequate airspeed during the landing.
Accident investigation:
 |
|
Sources:
NTSB NYC06LA121
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 08-Oct-2022 16:30 | ASN Update Bot | Added |
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