EASA SIB 2010-12R1: Loss of tail rotor effectiveness (LTE) or unanticipated yaw in helicopters

What to do

Pilots should receive both theoretical and practical flight training focused on the characteristics and function of the tail anti-torque system, especially in flight regimes prone to LTE. Training should be conducted by approved organizations and experienced instructors knowledgeable about LTE. National Aviation Authorities are recommended to ensure that all pilot licenses and flight instructor courses include dedicated LTE training and recovery procedures. No mandatory compliance deadlines are specified.

Summary

EASA Safety Information Bulletin 2010-12R1 addresses the phenomenon of Loss of Tail Rotor Effectiveness (LTE) or unanticipated yaw in helicopters. This bulletin applies to all single main rotor helicopters equipped with a tail anti-torque device and explains that LTE is a critical low-speed aerodynamic condition causing uncommanded yaw, which varies depending on the main rotor rotation direction. The document references several authoritative sources for understanding, preventing, and recovering from LTE.

What changed

EASA SIB 2010-12R1 revises the original bulletin to include a new Training Leaflet published by the European Helicopter Safety Team (EHEST) that provides additional safety recommendations on LTE. It also updates references by introducing the UK CAA CAP 789, which supersedes the previous CAP 768 guidance material.

Why it matters

Understanding LTE is crucial for helicopter operators, pilots, and training organizations because LTE has been identified as a contributing factor in multiple helicopter accidents. Proper training and awareness help pilots recognize and recover from LTE conditions, enhancing flight safety and reducing accident risk. Compliance with the recommendations supports safer helicopter operations and aligns with best practices promoted by aviation authorities.