FTW95IA397 · MBB BO-105C
MBB BO-105C · Incident: airframe, component or system failure en route
From Lafayette Regional Airport (LFT) to an unrecorded destination
Event
- NTSB case
- FTW95IA397
- 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
- Incident
- 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 BO-105C
- Aircraft type
- MBB BO-105
- 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
- N91070
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Lafayette Regional Airport (LFT)To not recorded
- 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
- En route · cruise
- 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
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Electrical system › Shorted
- Safety system(other) › Not activated
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While over 'Fast Lane,' a visual check point on the highway approach to the Lafayette Regional Airport, the helicopter 'abruptly and violently pitched nose down.' It took both pilots pulling aft on the cyclic to level the helicopter. Once control was re-established, the PIC saw that the 'hyd block' light was illuminated and the Mast Moment Indicator (MMI) limit light was on steady. The helicopter was landed without further incident. Examination and testing of the Tandem Hydraulic Unit found the System 1 hydraulic pump leaking internally. A nick and an abrasion were found in the edge of its longitudinal control slider. Metallic chips were found in the hydraulic high and low pressure filters, and one chip was found in a groove of the longitudinal control slider. The electrical portion of the 'jam-proof system,' which should activate the back-up hydraulic system two in case of a control slider jamming, only worked randomly. The connector was heavily corroded and the magnetic core of the solenoid valve had an internal short circuit.
Probable cause
a short in the 'jam proof system' solenoid valve which prevented activation of the backup hydraulic system and resulting in a cyclic hardover. Factors were the contaminated hydraulic fluid and the resulting jammed actuator (longitudinal control slider).
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW95IA397
- Event ID
- 20001207X04486
- Case number
- FTW95IA397
- 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, damage. 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: 62d653d9a7eec7d495bc16a1e78ccb530288fee47bcf828bf3a55a9a856ed2e5; retrieved 2026-09-22T23:15:04.677Z.