Air Methods Messerschmitt-Bolkow-Blohm BK 117 B-2 accident
Messerschmitt-Bolkow-Blohm BK 117 B-2 · Accident: system/component malfunction/failure (non-power) on approach
From Fond du Lac County Airport (FLD) to Sheboygan County Memorial Airport (SBM)
Event
- NTSB case
- CEN18LA115
- 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
- Unknown
- 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
- Charter & commuter
- 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
Messerschmitt-Bolkow-Blohm BK 117 B-2
- Aircraft type
- Messerschmitt Bolkow Blohm 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
- N1174U
- Operator
- Air Methods
- Onboard fatalities
- Unknown
- Route
- From Fond du Lac County Airport (FLD), Fond du Lac, WITo Sheboygan County Memorial Airport (SBM), Sheboygan, WI
- Aircraft age
- About 30 years (built 1988)
- 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 135: Air Taxi & Commuter
- 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
- Defining eventThe 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
- System/component malfunction/failure (non-power)
- 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
- Not determined › Not determined
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
Before departure on the air ambulance flight, standard flight control and hydraulic transfer checks were performed with no anomalies noted with the flight controls. The helicopter’s hover, departure, and cruise were normal. During his approach to the hospital, the pilot started a slow descent using the collective and performed the before landing checks; all systems were normal. However, when attempting to decelerate from cruise speed, the pilot noticed restricted cyclic control movement, about 1 inch in any direction, with normal collective and yaw control movement. He then chose to abort the descent and execute a precautionary landing at a nearby airport.
During the short flight to the airport, the pilot cycled the hydraulic test switch twice with no change noted to his flight controls. During the approach to land, the pilot held the cyclic trim switch aft in an attempt to gain additional aft cyclic authority. With continuous cyclic pressure against the aft stop, the pilot was able to slow the helicopter to 80 knots on final approach. The helicopter touched down near the runway centerline, skidded about 500 ft, exited the runway surface, and came to rest upright. The helicopter sustained substantial damage to the main rotor blades and fuselage structure.
Postaccident examination of the helicopter’s flight control system, including the trim system, did not reveal any evidence of malfunctions or failures that would have precluded normal operations. The cyclic trim was found in the full forward and left position. The flight control dual hydraulic pack was functionally tested on the helicopter and at a repair facility with no anomalies noted. Thus, the reason for the restricted cyclic control movement could not be determined.
Probable cause
The restricted cyclic control movement for reasons that could not be determined because postaccident examination and testing of the cyclic control system did not reveal any evidence of mechanical malfunctions or failures that would have precluded normal operation.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN18LA115
- Event ID
- 20180306X93227
- Case number
- CEN18LA115
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2018-03-05.
- API snapshot SHA-256: 0c858b0e1b4b0d41fc50b276c7b5cc227d831bbf33a2b76864bd843839263edd; retrieved 2026-09-16T06:35:13.190Z.