Aerospatiale AS-350B1 N350WM

Summary

On 13 July 1994 at about 13:38 local time, a Aerospatiale AS-350B1 registered N350WM, operated by Sea-Link Helicopters, Inc, was involved in an accident near Galveston, Texas, United States. 5 people were on board and 4 died, one was seriously injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

13 July 1994 at 13:38

Classification

Accident

Location

Galveston, Texas, United States

Coordinates

29.3005, -94.7894

Aircraft

Aerospatiale AS-350B1

Registration

N350WM

Category

Helicopter

Engines

1

Operator

Sea-Link Helicopters, Inc

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Unknown → Oil Tanker

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

FTW94FA231

4 people died.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.