What happened
On December 24, 2018, at approximately 22:15 CST, a MBB BK117 C-2 helicopter, registration N145EC, was performing a night air medical flight near Strum, Wisconsin. The flight departed from Chippewa Valley Regional Airport (EAU) at approximately 21:54 under night visual meteorological conditions with 10 statute mile visibility.
While executing a visual approach to a landing zone, the crew identified various obstructions, including trees, flag poles, and fire trucks. As the pilot approached the landing area at approximately 30 feet above ground level, a street sign was identified. In an attempt to avoid the sign, the pilot decelerated the aircraft, which caused the tail boom and rotor to lower. During this maneuver, the tail rotor made contact with a hose rack on a fire truck, causing the helicopter to spin. The pilot subsequently lowered the collective, leading to an impact with the terrain that damaged the landing gear skids.
The accident resulted in 3 minor injuries to the pilot and two crewmembers. The helicopter sustained substantial damage.
The investigation
Post-accident examination of the aircraft confirmed substantial damage to the tail rotor. The pilot reported that there were no mechanical failures or malfunctions prior to the accident that would have prevented normal operation.