ASN Wikibase Occurrence # 43451
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| Date: | Wednesday 13 July 1994 |
| Time: | 09:38 LT |
| Type: |  Aérospatiale AS 350B1 |
| Owner/operator: | Sea-link Helicopters, Inc |
| Registration: | N350WM |
| MSN: | 2099 |
| Year of manufacture: | 1988 |
| Total airframe hrs: | 2704 hours |
| Engine model: | TURBOMECA Arriel 1D |
| Fatalities: | Fatalities: 4 / Occupants: 5 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Gulf of Mexico, 11 miles off Galveston, Texas -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | |
| Oil Tanker, GM | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
THE PILOT REPORTED THAT THE HELICOPTER WAS CLIMBING THROUGH '...2,000 FEET WHEN A BUMP SIMILAR TO TURBULENCE WAS FELT. ANOTHER BUMP WAS FELT, FOLLOWED BY A MORE PRONOUNCED BUMP, THEN AIRCRAFT CONTROL WAS LOST.' HE ADDED THAT THE CYCLIC AND COLLECTIVE WERE UNRESPONSIVE. THE HELICOPTER IMPACTED THE WATER IN THE GULF OF MEXICO APRX 11 MILES OFFSHORE. ALL MAJOR COMPONENTS, EXCEPT THE VERTICAL FIN AND TAILROTOR GEARBOX, WERE RECOVERED. DURING A RECONSTRUCTION OF THE HELICOPTER, THE LEFT LATERAL SERVO ROD END WAS FOUND DISCONNECTED FROM THE SERVO EXTENSION. THE THREADS ON THE ROD END WERE INTACT AND APPEARED UNDAMAGED; HOWEVER, ONLY REMNANTS OF THE MATING INTERNAL THREADS IN THE SERVO EXTENSION REMAINED. ALMOST THE ENTIRE THREAD PROFILE WAS WORN AWAY LEAVING ONLY THE THREADED AREA THAT HAD BEEN LOCATED WITHIN THE KEYWAY SLOT OF THE ROD END. THE ZER0-TIME SERVO HAD BEEN INSTALLED 416 FLIGHT-HRS BEFORE THE ACCIDENT. THE LEFT LATERAL SERVO, WHICH IS CONNECTED BY A PUSH ROD TO THE CONTROLS AT THE MAIN ROTOR HEAD, CHANGES THE ATTITUDE OF THE HELICOPTER BY CHANGING THE ANGLE OF ATTACK OF THE MAIN ROTOR BLADES.
Probable Cause: INADEQUATE TORQUING OF THE LEFT LATERAL SERVO BY MAINTENANCE PERSONNEL, WHICH ALLOWED IT TO BECOME DISCONNECTED FROM THE CONTROLS, LEADING TO AN IN-FLIGHT LOSS OF CONTROL.
Accident investigation:
 |
|
Sources:
NTSB FTW94FA231
FAA register: 2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=350WM
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 24-Oct-2008 10:30 | ASN archive | Added |
| 02-Jul-2014 20:55 | Dr. John Smith | Updated [Time, Location, Nature, Departure airport, Destination airport, Source, Narrative] |
| 21-Dec-2016 19:24 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 10-Apr-2024 06:03 | ASN Update Bot | Updated [Time, Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative, Category, Accident report] |
Corrections or additions? ... Edit this accident description
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