Summary
We are proposing a new airworthiness directive (AD) for all Eurocopter Deutschland GmbH (ECD) MBB-BK 117 A-3, MBB-BK 117 A-4, MBB- BK B-1, MBB-BK 117 B-2, and MBB-BK C-1 helicopters equipped with a certain external-hoist system (hoist system) by requiring either deactivating the entire hoist system or deactivating the hoist system cable cutter function on the hoist system operator control handle (operator handle). This AD was prompted by an uncommanded activation of the hoist cable cutter function on an MBB-BK117 C-1 helicopter. This AD is intended to prevent uncommanded cutting of the hoist cable and subsequent injury to persons being lifted by the hoist.