Data-driven analysis and new findings on the loss of tail rotor effectiveness in helicopter accidents

Joseph Homer Saleh,Zhaoyi Xu,Weiqing Zhang,Anca Ioana Guvir,Martin Ma,Arega Margousian

doi:10.1038/s41598-022-06647-0

Abstract

Loss of tail rotor effectiveness (LTE) is an unstable dynamic phenomenon that affects single-rotor helicopters and frequently leads to accidents. LTE accidents recur with troubling regularity and show no sign of abatement. This work uncovers new data-driven findings pertaining to LTE and risk factors. First, a scorecard is developed covering a broad range of results to better understand LTE accidents. Second, the risk of LTE is derived for current helicopters. Third, a Deep Learning model is developed that captures the dependence between LTE risk and helicopter features. A danger zone is discovered in the design space for short tail rotor arm and high tail rotor RPM. The results challenge the prevailing narrative of LTE accidents as mere pilot errors and demonstrate an intrinsic propensity to these accidents is embedded in part in the helicopter design. The findings open the door to new, more effective safety interventions for LTE accident prevention.

Highlights

Loss of tail rotor effectiveness (LTE) is an unstable dynamic phenomenon that affects single-rotor helicopters and frequently leads to accidents
It was found that the combination of high main rotor tip speed and high tail rotor tip speed is associated with a higher risk of LTE, and that increasing the disk loading further expands the LTE danger zone. Why should these findings matter? It is generally accepted in the rotorcraft community that 60–70% of all helicopter accidents are due to pilot errors, including LTE accidents
Available data of civil helicopters from three sources were used in this work: [1] the Federal Aviation Administration (FAA) for registration records; [2] the National Transportation Safety Board (NTSB) for accident records; and [3] helicopter manufacturer manuals for technical information

Summary

Introduction

Loss of tail rotor effectiveness (LTE) is an unstable dynamic phenomenon that affects single-rotor helicopters and frequently leads to accidents. Loss of tail rotor effectiveness (LTE), known as unanticipated yaw, is a distinctive dynamic phenomenon that affects single-rotor helicopters and frequently leads to loss of control resulting in accidents and casualties. A low-speed phenomenon, LTE depends on several factors, in particular the direction and strength of the wind relative to the helicopter, and it manifests itself in a seemingly un-commanded yaw motion generally in the opposite direction of the rotation of the main rotor blades. Technique, which called for full opposite pedal and forward cyclic These findings remain the bedrock of today’s understanding and handling of LTE

Methods

Results

Conclusion