Loss of Tail Rotor Effectiveness Settling with Power

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Loss of Tail Rotor Effectiveness/Settling with
Power
John Musser
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LTE

• All helicopters with tail rotors are susceptible.
• Increased risk for under-powered aircraft.
• Common cause of incidents/accidents.
• AVOIDABLE!

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What is LTE?

• LTE is the tail rotors inability to produce
  sufficient amount of lift to counter-act main
  rotor torque. (PREDONIMANTLY an aerodynamic
  complication)

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LTE vs. Loss of Thrust

• LTE
• Occurs at low or no airspeed
• Aerodynamic causes
• High Gross Weight
• High Altitude
• High Temp and/or DA
• Adverse Winds
• OGE Hover
• Improper tail rotor rigging

• Loss of Thrust
• Effects aircraft at any speed
• Mechanical causes
• Break in drive train (t/r drive shaft)
• Loss of components

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Recovery from LTE

• Reduce power
• Allow Aircraft to weather vain
• Continue to fly the aircraft in the direction of
  spin (right) to achieve forward airspeed

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Prevention of LTE

• Ensure sound pre-mission planning
• Maintain wind awareness (tail/Right X-wind)
• Avoid maneuvering flight below 40kts
• Conduct an OGE power check if your flight profile
  is expected to include OGE hovers.

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What Altitude is OGE?

• 1 ¼ Rotor diameter
• R44 rotor dia. 33 ft
• Plus ¼ rotor dia 8 Ft
• R44 OGE 41 Ft.
• Safe to say that below 40 ft, ground effect
  begins to occur.

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Settling with Power

• Settling in your own downwash
• Vortex Ring State
• Unlike Autorotation, pitch is applied

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Conditions for Settling with Power

• 10 20 -30 rule
• 10 knots or less of airspeed
• 20-100 of available power applied
• Rate of decent of 300fpm or greater

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Typical situations

• Conducting steep approach
• Conducting formation approach
• Attempting to arrest a descent from OGE

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Recovery from Settling with Power

• Directional Flight!! (achieve ETL / clean air)
• Reduce collective
• Apply directional cyclic

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Conclusion

• Safe pilots are aware of their limitations AND
  the limitations of their aircraft.
• Dont suffer from LPE (loss of planning
  effectiveness)
• Maintain Situational Awareness (SA)

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QUESTIONS?