CEN19TA075

NTSB accident investigation · MBB BK117 · Strum, WI · December 25, 2018

Accident · Minor injuriesFinal report
Date
December 24, 2018, 22:15 local (Dec 25, 2018, 04:15 UTC)
Place
Strum, WI
Injuries
3 minor
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N145ECMBB BK117
Defining event
Landing: Collision during takeoff/land
Weather
Visual (VMC) · Night
Status
Completed · report June 29, 2020
Report
Approved by Office Director
NTSB office
Central Region
Parties
Flight Standards District Office
FAA report
20181224021969A
Case key
98928

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's failure to maintain clearance from the fire truck.

Findings · 3

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Attention/monitoring: monitoring environmentPersonnel issues › Psychological · PilotAll aircraft: 809 casesProbable cause
Performance/control parameters: altitudeAircraft › Aircraft oper/perf/capability · Not attained/maintainedAll aircraft: 1,310 casesProbable cause
Object/animal/substance: ground vehicleEnvironmental issues › Physical environment · Contributed to outcomeAll aircraft: 132 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The pilot and two crewmembers were on a night air medical flight. While on approach to the landing zone with several obstructions nearby, the pilot noticed a street sign and slowed the helicopter, which lowered the tailboom and tail rotor. The helicopter's tail rotor then struck a hose rack on a fire truck, which resulted in a loss of control and impact with the ground. The helicopter sustained substantial damage to the tail rotor. The pilot reported no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.

Factual narrative

On December 24, 2018, about 2215 central standard time, a Eurocopter Deutschland MBB-BK117 C-2 helicopter, N145EC, impacted a fire truck during a visual approach to a landing zone near Strum, Wisconsin. The commercial pilot and two crewmembers received minor injuries, and the helicopter was substantially damaged. The helicopter was registered to U.S. Bank and operated by Mayo Clinic under the provisions of Title 14 Code of Federal Regulations Part 135 as an air medical flight. Night visual meteorological conditions prevailed for the flight, which departed from Chippewa Valley Regional Airport (EAU), Eau Claire, Wisconsin, about 2154. The pilot reported that while on approach to a landing zone, the crew called out obstructions such as trees, fire trucks, and flag poles. About 30 ft above ground level, the pilot noticed a street sign and decelerated the helicopter, which resulted in a lowering of the tail boom and rotor. During this movement, the tail rotor contacted the hose rack on a fire truck and the helicopter started to spin. The pilot lowered the collective control and the helicopter impacted terrain, which damaged the landing gear skids. Postaccident examination revealed that the helicopter sustained substantial damage to the tail rotor. The pilot reported there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. Following the accident, the operator initiated the following actions: Reviewed current company policies regarding confined area/ scene landing to verify pilots were provided the proper guidance and training to land at a non-airport/helipad environment. Provided training to all pilots regarding expectations in these landing scenarios and steps to assist in decision making and determining the suitability of a landing area. Introduced scene landing scenarios into annual simulator training. Developed annual syllabi for pilots to complete annually to refresh themselves and medical crew on basic confined area/scene landing protocols. Developed an off-airport landing checklist that included: 1. Ensure the size of the area is adequate, 2. The landing surface is suitable. Is it level is there mud, ice, blowing snow, etc. 3. Review obstacles in or around the landing zone (wires, vehicles, flagpoles, fences, street signs, etc.), 4. The best approach direction and type of approach (Normal, steep, vertical), 5. The best departure direction and type of departure (Normal, vertical), 6. Power requirements needed to avoid obstacles.

Aircraft

Registration
N145EC
Reported as
MBB BK117 (C2)
Category
Helicopter
Serial number
9181
Built
2008
Airframe hours
6,055
Engines
Turbomeca Arriel 1E2, 790 horsepower, turbo shaftTurbomeca Arriel 1E2, 790 horsepower, turbo shaft
Damage
Substantial damage
Flight
Part 135
Operator
Mayo Clinic, doing business as Mayo Clinic
Registered owner
U.S. Bank
Airworthiness certificate
Standard, Transport
Last inspection
AAIP · December 24, 2018
Departed
EAU · Eau Claire, WI
Destination
Strum, WI
Flight plan
Company VFR
Equipment
Auto-pilot, ADS-B, Video recording device, Satellite tracking device, Onboard weather, Electronic primary flight display, Electronic multifunction display, Data recorder

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
52
Injuries
Minor
Certificate
Commercial
Instrument ratings
Helicopter
Medical
Class 2, With waivers/limitations
Last flight review
October 22, 2018
Seat
Front
Restraint
5-point
Flight hours
3,842 total · 1,064 in this make and model · 3,842 as pilot in command · 42 in the last 90 days · 9 in the last 30 days · 0 in the last 24 hours

Weather

Conditions
Visual (VMC) · Night
Wind
Calm
Visibility
10 statute miles
Temperature
18 °F, dew point 12 °F
Observed at
KEAU, 19 nm away

Docket · 1

The files NTSB released with the investigation on December 9, 2019, on NTSB’s docket system: statements, records, photos and specialists’ reports. 823 KB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.