FTW95FA394 · MBB BO-105C
Hermann Hospital Life Flight MBB BO-105C · Accident: airframe, component or system failure en route
From Life Flight/Refuel Heliport (TE11) to an unrecorded destination
Event
- NTSB case
- FTW95FA394
- 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 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
- N650MS
- Operator
- Hermann Hospital Life Flight
- Onboard fatalities
- Unknown
- Route
- From Life Flight/Refuel Heliport (TE11)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
- Destroyed
Cause areas
- Fluid, oil › Flow restricted
- Lubricating system, oil port/passage, internal › Blocked(partial)
- Rotor drive system, engine to transmission drive › Disconnected
- Rotor drive system, engine to transmission drive › Failure
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that during cruise flight at 800 feet MSL, a 'whine' was heard, which was 'slightly' different from the normal whine of the engines. A loud 'snap' or 'bang' was heard followed by severe vibrations. After determining a dual engine failure, the number one engine fire warning light illuminated, and the smell of smoke was noticed. An autorotation was initiated to a mall parking lot. During the autorotation, the pilot increased collective to clear trees bordering the parking lot. The helicopter touched down and slid approximately 200 feet to a stop. When the nurse opened the door to evacuate, smoke billowed into the cabin from the 'tunnel area.' After confirming that the flight crew was well clear, the pilot exited the helicopter. Examination of the helicopter revealed the drive shaft for the left engine had separated from the transmission input shaft flange. Examination of the main transmission lower housing revealed debris partially blocking the oil channel for the left side input pinion. Examination of both engines revealed internal thermal and foreign object damage.
Probable cause
the failure of the main transmission's #1 (left) input pinion assembly, due to the partially blocked oil passage which reduced oil flow, resulting in the disconnect of the drive shaft.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW95FA394
- Event ID
- 20001207X04480
- Case number
- FTW95FA394
- 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: ada384be70a13ade576bd494ba8a3292cae3e76c92d923227033ad92d2a06dab; retrieved 2026-09-22T23:16:09.361Z.