AVIATION Reports - 2005 - A05F0025

Table of Contents

1. 1.0 Factual Information
   1. 1.1 History of the Flight
   2. 1.2 Damage to the Aircraft
   3. 1.3 Pilot Information
   4. 1.4 Aircraft Information
   5. 1.4.1 Original Certification of the AS 350 Series
   6. 1.4.2 Conversion History
   7. 1.4.3 Weight and Balance
   8. 1.4.4 Maintenance
   9. 1.4.5 Engine Information
   10. 1.4.6 Hydraulic Flight Control System
   11. 1.4.6.1 General Description
   12. 1.4.6.2 Hydraulic System Components
   13. 1.4.6.3 Hydraulic Servo Actuator Operation
   14. 1.4.6.4 Hydraulic System Pump Operation
   15. 1.4.6.5 Hydraulic System Control and Monitoring
   16. 1.4.6.6 Hydraulic System Malfunction
   17. 1.4.6.7 Hydraulic System Certification
   18. 1.4.6.8 Hydraulic System Failure Procedures in the Rotorcraft Flight Manual
   19. 1.4.7 Main Rotor Control
   20. 1.4.7.1 Principles of Rotor Control
   21. 1.4.7.2 Collective Pitch Action
   22. 1.4.7.3 Cyclic Pitch Action
   23. 1.4.8 AS 350 B2 Klaxon Warning Horn
   24. 1.4.8.1 Low Rotor Speed Aural Warning
   25. 1.4.8.2 Low Hydraulic System Pressure Aural Warning
   26. 1.4.8.3 Main Rotor Low Speed Warning Certification
   27. 1.5 Meteorological Information
   28. 1.6 Aerodrome Information
   29. 1.7 Flight Recorders
   30. 1.8 Wreckage and Impact Information
   31. 1.8.1 Mechanical Flight Control System
   32. 1.8.2 Servo Examination
   33. 1.8.3 Servo Actuator Accumulators Examination
   34. 1.8.4 Hydraulic Cut-off Switch Examination
   35. 1.8.5 Hydraulic Test Switch on the Centre Pedestal
   36. 1.8.6 Hydraulic Fluid Examination
   37. 1.8.7 Warning Horn and Electrical System
   38. 1.8.8 Electrical Fuses and Circuit Breakers
   39. 1.8.9 Electrical System Printed Circuit Boards
   40. 1.9 Medical and Pathological Information
   41. 1.10 Survival Aspects
   42. 1.11 Tests and Research
   43. 1.11.1 Australian Department of Defence Evaluation of the AS 350 BA
   44. 1.11.2 Hydraulic Cut-off Switch Failures
   45. 1.12 Organizational and Management Information
   46. 1.12.1 Transport Canada
   47. 1.12.1.1 Hydraulic Failure - Flight Control Loads
   48. 1.12.1.2 Canadian Airworthiness Directives and Airworthiness Notice
   49. 1.12.1.3 Canadian Rotorcraft Flight Manual Supplement Number 7
   50. 1.12.2 Direction Générale de l'Aviation Civile
   51. 1.13 Other Relevant Information
   52. 1.13.1 Hydraulic Test Switch Inadvertent Activation
   53. 1.13.2 Electro-Valve Wiring Modification
   54. 1.13.3 Electro-Valve Wiring Diagram
   55. 1.13.4 Hydraulic Cut-off Switch Electrical Rating
   56. 1.13.5 Pilot Reactions to the Klaxon Warning Horn
   57. 1.13.6 Hydraulic Servo Actuator Transparency
   58. 1.13.6.1 General
   59. 1.13.6.2 Cause of Servo Transparency
   60. 1.13.6.3 Effects of Servo Transparency
   61. 1.13.6.4 Procedures to Recover from Servo Transparency
   62. 1.13.6.5 Previous Losses of Control in the AS 350
2. 2.0 Analysis
   1. 2.1 Introduction
   2. 2.2 Hydraulic System1
   3. 2.2.1 Flight Control Malfunctions
   4. 2.2.2 Servo Actuator Anomalies
   5. 2.2.3 Servo Actuator Accumulators
   6. 2.2.4 Control Following a Servo Actuator Malfunction
   7. 2.3 Pilot Actions
   8. 2.4 Hydraulic Fluid Contamination
   9. 2.5 Electrical System
   10. 2.5.1 General
   11. 2.5.2 Collective Hydraulic Cut-off Switch
   12. 2.5.3 Printed Circuit Boards
   13. 2.5.4 Hydraulic Test Switch
   14. 2.5.5 Low Main Rotor Speed Aural Warning Horn
   15. 2.6 Possible Causal Factors
   16. 2.7 Summary
3. 3.0 Conclusions
   1. 3.1 Finding as to Causes and Contributing Factors
   2. 3.2 Findings as to Risk
4. 4.0 Safety Action
   1. 4.1 Action Taken
   2. 4.1.1 Aural Warning for Low Rotor Speed and Low Hydraulic Pressure
   3. 4.1.2 Protective Cover for the Hydraulic Test Switch of AS 350 Helicopters
   4. 4.2 Action Required
   5. 4.2.1 Underrated Hydraulic Cut-off Switch
5. Appendices
   1. Appendix A - Previous AS 350 Loss-of-Control Occurrences
   2. Appendix B - List of Laboratory Reports
   3. Appendix C - Glossary
6. Photos
   1. Photo 1 - C-GNMJ After the Hard Landing
   2. Photo 2 - Hydraulic Cut-off (HYD CUT OFF) Switch
   3. Photo 3 - Hydraulic Test (HYD TEST) Switch
7. Figures
   1. Figure 1 - Accident Site Map
   2. Figure 2 - AS 350 B2 Hydraulic System Diagram
   3. Figure 3 - Main Rotor Assembly Showing Servos
   4. Figure 4 - Servo Placement on Stationary Swashplate
   5. Figure 5 - Schematic Drawing of Servos and Swashplate

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