No fatalities

Eurocopter BK-117 Sustains Tailrotor Damage from Unsecured Cowling in Pittsburgh (N145HN)

Pittsburgh, PA, United States

On April 26, 2016, an EUROCOPTER DEUTSCHLAND GMBH MBB BK 117 C-2 C2 (registration N145HN) operated by AIR METHODS CORP was involved in an aviation accident near Pittsburgh, PA. No fatalities were reported. Investigators recorded the probable cause as: Maintenance personnel’s failure to properly secure the left vertical fin cowling during recent maintenance, which resulted in its separation and subsequent contact with the tail rotor system during flight. This summary draws on records from NTSB; 17 related events involving the same aircraft type or operator are linked below.

SourcesNTSBPrimary reportUpdated 1785761257Data APIEditorial standards

On April 26, 2016, a Eurocopter BK-117 C-2 operated by Air Methods Corp sustained substantial tailrotor damage after the left vertical fin cowling partially separated and contacted a blade. The fasteners on the cowling were found unlocked, consistent with improper securing during prior maintenance.

Incident Overview

On April 26, 2016, at about 1500 eastern daylight time, a Eurocopter Deutschland GMBH MBB-BK-117 C-2, registration N145HN, operated by Air Methods Corp, was substantially damaged during cruise flight to West Penn Hospital Heliport (PN80) in Pittsburgh, Pennsylvania. The commercial pilot, three crewmembers, and one patient were not injured. The on-demand air medical flight was conducted under 14 Code of Federal Regulations Part 135. Visual meteorological conditions prevailed, and a company flight plan was filed for the flight that originated from Grafton City Hospital Heliport (22WV) in Grafton, West Virginia, about 1430.

Pilot Report and Examination

The pilot reported that the patient transfer flight was the second flight of the day, following maintenance work performed on the helicopter earlier that morning. The flight was uneventful; however, after landing, the pilot noticed that the left vertical fin cowling had partially separated and came in contact with a tailrotor blade. The pilot added that 8 of the 11 fasteners on the left vertical fin cowling were unlocked.

Examination of the tailrotor blade by representatives from the helicopter manufacturer revealed that the blade had sustained substantial damage. Examination of the helicopter by a Federal Aviation Administration inspector revealed that the Dzus fasteners on the right vertical fin cowling remained secured, while those on the left vertical fin cowling were unlocked, consistent with them not being properly secured by maintenance personnel following the earlier maintenance work.

Additionally, the operator reported that there were no mechanical failures or malfunctions with the helicopter.

Contributing factors

Maintenance personnelIncorrect service/maintenance