MBB BK 117 A-4 N401PH

Summary

On 25 May 1993 at about 14:14 local time, a MBB BK 117 A-4 registered N401PH, operated by Petroleum Helicopters, Inc., was involved in an accident near Lafayette, Louisiana, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 May 1993 at 14:14

Classification

Accident

Location

Lafayette, Louisiana, United States

Nearest airport

Lafayette Regional (LFT)

Coordinates

Not recorded

Aircraft

MBB BK 117 A-4

Registration

N401PH

Category

Helicopter

Engines

2

Operator

Petroleum Helicopters, Inc.

Operating rule

Part 91: General Aviation

Purpose of flight

Unknown

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW93FA163

Nobody was injured.

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

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

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.