FTW93FA163 · MBB BK 117 A-4
Petroleum Helicopters MBB BK 117 A-4 · Accident: loss of control in flight on approach
From Lafayette Regional Airport (LFT) to Lafayette Regional Airport (LFT)
Event
- NTSB case
- FTW93FA163
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
MBB BK 117 A-4
- Aircraft type
- MBB BK-117
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N401PH
- Operator
- Petroleum Helicopters
- Onboard fatalities
- Unknown
- Route
- From Lafayette Regional Airport (LFT)To Lafayette Regional Airport (LFT)
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Approach · VFR pattern final
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control in flight
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Company maintenance personnel › Maintenance, installation, improper
- Rotorcraft flight control, cyclic control rod › Movement restricted
Approximate · Estimated position: the centre of Lafayette, LA, the place the record names. Not the accident site.
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.
Probable cause
CYCLIC CONTROL ROD MOVEMENT WAS RESTRICTED DUE TO IMPROPER INSTALLATION OF THE LATERAL CYCLIC CONTROL ROD BY COMPANY MAINTENANCE PERSONNEL.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW93FA163
- Event ID
- 20001211X12383
- Case number
- FTW93FA163
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 95c79767916000965ad5ed9fd1d1814e91c982f75a1230db33cae0306d28be14; retrieved 2026-09-23T02:03:47.174Z.