(Pilot) Heard A “Bang” And Felt A “Very Strong” Vibration In The Tail Rotor Pedals

Location: Fargo, GA Accident Number: ERA23LA369
Date & Time: September 13, 2023, 12:55 Local Registration: N273AM
Aircraft: Eurocopter Deutschland GMBH EC135T2 Injuries: 2 None
Flight Conducted Under: Part 91: General aviation - Positioning

On September 13, 2023, at 1255 eastern daylight time, a Eurocopter EC135T2, N273AM, was substantially damaged when it was involved in an accident near Fargo, Georgia. The airline transport pilot and a passenger were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 positioning flight.

In a written statement, the pilot stated the helicopter had been in cruise flight approximately 1 hour about 1,500 ft mean sea level (msl) when the accident occurred. She stated that there were no faults or warnings displayed and all systems were in the “normal” range when she heard a “bang” and felt a “very strong” vibration in the tail rotor pedals. The pilot immediately identified a site for a precautionary landing which she completed without further incident.

Initial examination of the Fenestron, a 10-bladed tail rotor that acts as a ducted fan for antitorque control, revealed that one blade was separated at its root. The cover for the tail rotor gearbox and pitch-change controls was separated and found directly beneath the gearbox. The surrounding Fenestron shroud was damaged. All blade grips remained in their mounts, and the remaining 9 blades appeared intact.

The pilot held an airline transport certificate with ratings for rotorcraft-helicopter and instrument helicopter. Her Federal Aviation Administration (FAA) second class medical certificate was issued November 8, 2022. The pilot declared 5,867 total hours of flight experience, of which 5,816 were in helicopters and 970 hours were in the accident helicopter make and model.

According to FAA and maintenance records, the helicopter was manufactured in 2003 and was powered by two Turbomeca Arrius 2B 492-horsepower engines. The helicopter’s most recent inspection under the operator’s approved inspection program was completed September 12, 2023, at 9,484 total aircraft hours.

The Fenestron blades were harvested and forwarded to the NTSB Materials Laboratory in Washington, DC, for examination. The blades were numbered 1-10, with the fractured blade identified as No. 10. The separated portion of the No. 10 blade was not recovered. The examination of the fracture surface of the No. 10 blade revealed features consistent with fatigue. All 10 blades were retained for further examination.

FMI: www.ntsb.gov