XN000022-1974-05-07 — Page 5

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TUESDAY, HAY 7, 1974

INQUIRY INTO +PIPER+ INCIDENT COMPLETED

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THE INVESTIGATION INTO THE CAUSE OF THE ACCIDENT INVOLVING THE HONG KONG AERO CLUB'S PIPER PA-28-140, VR-HGB, AT HONG KONG AIRPORT ON APRIL 12, 1974 HAS BEEN COMPLETED.

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AFTER TAKE-OFF THE PILOT HEARD A CONTINUING KNOCKING NOISE AND IMMEDIATELY REQUESTED AN EMERGENCY 'LANDING. THE LANDING WAS NORMAL UP TO THE POINT WHERE THE UNDERCARRIAGE SHOULD HAVE SUPPORTED THE AIRCRAFT.

THERE WAS HOWEVER A PRONOUNCED TENDENCY FOR THE AIRCRAFT TO SWING TO THE LEFT AND IT BECAME IMPOSSIBLE TO CONTROL THE AIRCRAFT ON THE GROUND. IT RAN OFF THE RUNWAY AND CAME TO REST ON AN EARTH MOUND. BOTH MAIN UNDERCARRIAGE WHEELS AND BRAKE UNITS WERE WRENCHED OFF, THE PROPELLOR, FLAPS AND UNDER-SURFACES OF THE AIRCRAFT WERE DAMAGED. NO INJURIES WERE SUFFERED BY THE TWO PILOTS.

THE CAUSE OF THE ACCIDENT WAS FOUND TO BE THE FAILURE OF A METAL TORQUE LINK ON THE LEFT UNDERCARRIAGE UNIT. WITH THIS FAILURE THE LEFT UNDERCARRIAGE UNIT FELL COMPLETELY FREE FROM THE ATTACHING STRUT AND WAS SUSPENDED ONLY BY THE BRAKE PIPE LINE.

THE PILOT WAS NOT AWARE OF THE CAUSE OF THE KNOCKING NOISE, NEITHER COULD HE HAVE KNOWN THAT THE LEFT UNIT OF HIS UNDER- CARRIAGE WAS BROKEN. HE WAS ABLE TO MAINTAIN DIRECTIONAL CONTROL UNTIL THE AIRCRAFT WEIGHT WAS NO LONGER BEING BORNE BY THE AERODYNAMIC FORCE. WITH ONLY ONE UNDERCARRIAGE UNIT SUPPORTING THE AIRCRAFT, DIRECTIONAL CONTROL BECAME IMPOSSIBLE.

THE BROKEN TORQUE LINK WAS SUFFERED AN INCIPIENT FRACTURE. METALLURGIC EXAMINATION AND THE OF THE FAILURE.

INSPECTED AND FOUND TO HAVE THE LINK HAS BEEN SENT FOR AIRCRAFT MANUFACTURER NOTIFIED

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