Action Prompted By EASA, Transport Canada ADs

The FAA is proposing to adopt a new airworthiness directive (AD) for Eurocopter Deutschland GmbH (ECD) Model BO-105A, BO-105C, BO-105S, BO-105LS A-1, BO-105LS A-3, MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A- 4, MBB-BK 117 B-1, MBB-BK-117 B-2, and MBB-BK 117 C-1 helicopters to require inspections for corrosion or thread damage to each tail rotor balance weight (weight) and each tail rotor control lever (lever).

This proposed AD is prompted by an EASA AD and a Transport Canada Civil Aviation (TCCA) AD, both issued based on a report that corrosion was detected on a weight in the area of the attachment thread on a model BO-105 helicopter. The proposed actions are intended to detect corrosion and thread damage in the threaded area of the weight and lever, and to prevent failure of a weight or lever, separation of tail rotor parts, severe vibration, and subsequent loss of control of the helicopter.

The proposed AD would require compliance with specified portions of the manufacturer's service bulletin in conducting repetitive visual inspections of each weight and lever and would provide procedures for installing a weight or lever. Additionally, it proposes allowable tolerances for corrosion or thread damage on the threaded portion of a weight or lever and would require that a part with corrosion or mechanical damage in excess of allowable tolerances be replaced with an airworthy part.

The FAA's proposed AD does not provide an extra 60 flight hours or 6 months beyond the repetitive compliance time of 600 flight hours or 48 months for the repetitive inspections, as stipulated by both the European and Canadian ADs. These proposals only apply to those model helicopters type-certificated in the United States.

Comments are due on the proposed AD by October 29.

FMI: Federal Register Notice