EASA SIB 2008-79: Eurocopter Deutschland EC 135 and EC 635 Helicopters - Unintended Single-Engine Take-Off

What to do

Owners and operators of EC 135 and EC 635 helicopters should review the advisory information and ensure that all pilots are familiar with the cockpit indications of single-engine operation and the Flight Manual procedures for pre-takeoff and takeoff checks. Pilots must perform the recommended checks carefully to avoid unintended single-engine takeoffs. In case of an unintended single-engine takeoff, pilots should follow the suggested recovery procedures outlined in the bulletin. There is no mandatory compliance deadline as this is an informational bulletin.

Summary

EASA Safety Information Bulletin 2008-79 is an advisory document addressing an increase in unintended single-engine take-off events in Eurocopter Deutschland EC 135 and EC 635 helicopters. It provides guidance to pilots on recognizing cockpit indications of single-engine operation before takeoff and reinforces adherence to established Flight Manual procedures. The bulletin highlights the risks of engine damage and collision hazards during such events and emphasizes that intentional single-engine takeoffs are not authorized despite the helicopters' high one-engine inoperative power capability.

What changed

This bulletin introduces an advisory from Eurocopter Deutschland GmbH to inform operators of EC 135 and EC 635 helicopters about the risk of unintended single-engine takeoffs. It clarifies cockpit indications to detect single-engine conditions and reiterates the importance of following existing Flight Manual checks to prevent these events. The document also provides recommended procedures for pilots to follow if an unintended single-engine takeoff occurs.

Why it matters

The bulletin is important for aviation professionals because unintended single-engine takeoffs can cause significant engine damage and increase the risk of accidents near takeoff sites. Operators and maintenance teams must ensure that pilots are trained to recognize and respond correctly to engine indications to maintain safety. Compliance with the Flight Manual procedures helps prevent hazardous situations and protects both crew and aircraft.