NTSB Identification: FTW93FA163.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Tuesday, May 25, 1993 in LAFAYETTE, LA
Probable Cause Approval Date: 08/31/1994
Aircraft: MBB BK 117 A-4, registration: N401PH
Injuries: 2 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

AFTER EXPORTATION FROM CANADA, MBB BK 117 HELICOPTER WAS BEING RE-ASSEMBLED & MODIFIED FROM MODEL A-3 TO MODEL A-4; 24 HOUR/DAY SCHEDULE WAS USED TO EXPEDITE MODIFICATION FOR USE AS AIR AMBULANCE. SHIFT CHANGE OCCURRED DURING MAINTENANCE ON VERTICAL CONTROL TUBES; WHEN COMPLETED, HELICOPTER WAS FLOWN ON TEST FLIGHT. NO ANOMALIES OF FLIGHT CONTROLS WERE NOTED UNTIL FLARING TO HOVER BEFORE LANDING. PILOT SAID THAT WHILE POWER WAS BEING APPLIED, CYCLIC & PEDALS WERE MANIP- ULATED ACCORDINGLY. LEFT MOVEMENT OF CYCLIC WAS REQUIRED TO OVERCOME (ROLL &) DRIFT TO RIGHT. AT THAT TIME, THE PILOT NOTED INSUFFICIENT CYCLIC CONTROL & THE HELICOPTER CONTINUED TO ROLL RIGHT UNTIL THE MAIN ROTOR BLADES STRUCK THE GROUND. THE HELICOPTER THEN IMPACTED ON ITS RIGHT SIDE & SLID TO A STOP. AN INVESTIGATION REVEALED THE LATERAL & COLLECTIVE UPPER ADJUSTABLE CONTROL RODS HAD BEEN INTERCHANGED & COLOR CODING REPAINTED. THE INTERCHANGE OF CONTROL RODS RESULTED IN A MISRIGGED SWASHPLATE WITH A HIGHER PRESET COLLECTIVE PITCH & A RIGHT TILT OF THE SWASHPLATE.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

CYCLIC CONTROL ROD MOVEMENT WAS RESTRICTED DUE TO IMPROPER INSTALLATION OF THE LATERAL CYCLIC CONTROL ROD BY COMPANY MAINTENANCE PERSONNEL.

Full narrative available

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