Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model BO-105, BO-105A, BO-105C, BO-105S, BO-105LS A-1 helicopters. This proposal would require a ground test and inspection of the tandem hydraulic switch-over system (switch-over system) for component wear and parts replacement, if necessary. This proposal is prompted by incidents involving Model BO-105 series helicopters in which, during the switch-over from Hydraulic System 1 to Hydraulic System 2, a 3-inch drop in the collective occurred, caused by component wear in the switch-over system. The actions specified by the proposed AD are intended to detect switch-over system component wear, which could result in a sudden drop in the collective and a sudden loss of altitude.