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Daniel C. Dugan, NASA CDR Kevin J. Delamer, USN

GOVERNMENT. ACADEMIA. INDUSTRY. The Implications of Handling Qualities in Civil Helicopter Accidents Involving Hover and Low Speed Flight. NRTC. Daniel C. Dugan, NASA CDR Kevin J. Delamer, USN. WHEN HELOS GO BAD. Introduction Background Analysis Results Stability Augmentation

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Daniel C. Dugan, NASA CDR Kevin J. Delamer, USN

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  1. GOVERNMENT ACADEMIA INDUSTRY The Implications of Handling Qualities in Civil Helicopter Accidents Involving Hover and Low Speed Flight NRTC Daniel C. Dugan, NASA CDR Kevin J. Delamer, USN

  2. WHEN HELOS GO BAD

  3. Introduction Background Analysis Results Stability Augmentation Directional Control Teetering Rotors Instrument Flight Conclusions Recommendations

  4. 4 Army Helicopters Hover in DVE (Night, Dust, …) Equipped with Rate Command SAS “Marginal” HQ KEY’S STUDY - 1999

  5. U.S. Army Helicopter Mishap Causes Hovering Flight Data from 276 Mishaps in Hovering Flight, 1986-1996 UH-60 / CH-47D Data from David L. Key, “Analysis of Army Helicopter Pilot Error Mishap Data and the Implications for Handling Qualities,” 25th European Rotorcraft Forum, Rome, Italy: September 14-16, 1999. AH-64A / OH-58D

  6. “U.S. Civil Rotorcraft Accidents - 1963-1997” - Harris, Kasper, Iseler “Analysis of US Civil Rotorcraft Accidents, 1990 - 1996 - Iseler and DeMaio …….” “Final Report of the Helicopter Accident Analysis Team,” DOD, FAA, and NASA “Near Term Gains in Rotorcraft Safety Strategies for Investment” - Workshop ADDITIONAL STUDIES SURVEYED

  7. HARRIS, KASPER, ISELER 1963-1997 1114 Total Mishaps • Piston and Turbine Rotorcraft • All Flight Regimes 13.2 % Due to Loss of Control 13.2% 247 Fatalities 228 Serious Injuries 319 Helicopters Destroyed

  8. 547 Accidents, Hover or Low Speed, 1993-2004 (Gyrocopters not Included) 126 or 23% attributed to Loss of Control which could be attributed to poor HQ 127 Fatalities, 97 Serious injuries, and 134 Helicopters destroyed THIS STUDY

  9. HOVER AND LOW AIRSPEED MISHAPS 1993-2004 547 Mishaps Reviewed 126 Due to Loss of Control (HQ) 15 Manufacturers* Over 30 Models 23 % * - All kit / homebuilt included as one manufacturer Handling Qualities issues accounted for a greater percentage of Hover mishaps than mishaps overall (23% versus 13%)

  10. HELICOPTER IN HOVER VS. AIRPLANE FAR 27 SFENA MINI-STAB HELISAS STABILITY AUGMENTATION

  11. EXTERNAL LOAD OPERATIONS MISHAPS 6% FLIGHT HOURS 15% • 85 Mishaps • 38 Fatalities • 26 Serious Injuries • 26 Helos Destroyed 30% FATALITIES

  12. Mission Analysis Personal Use and Instructional Flights Accounted for Almost Half of the Mishaps While Accounting for Only 15% of Flight Hours* 48.2% * - Utilization Rates from FAA Aerospace Forecasts

  13. LOSS OF TAIL ROTOR EFFECTIVENESS AC 90-95 “UNANTICIPATED RIGHT YAW IN HELICOPTERS” MORE CRITICAL IN HOVER AND LOW SPEED FLIGHT FACTORS: WIND DIRECTION DIRECTIONAL CONTROL POWER AND CONTROL MARGINS POWER APPLIED (COLLECTIVE PITCH) PILOT SKILLS AND EXPERIENCE DIRECTIONAL CONTROL

  14. Initial Data Survey - 297 Hover/Low Airspeed Mishaps - 45 LTE Related (15%) Expanded Data Set - 547 Hover/Low Airspeed Mishaps - 82 LTE Related (15%) LTE PERCENTAGES

  15. MISHAPS BY TYPE ROTOR SYSTEM 56 % Number of Mishaps

  16. PROS Rugged Construction Blade Retention Failures Rare Start/Stop in High & Gusty Winds Not Susceptible to Ground Resonance Cost/Low Complexity CONS Susceptible to Mast Bumping - Usually Fatal in Flight Control Lags - can Induce PIO Vibration (Two Blade Systems) TEETERING ROTORS(Author’s Opinion/Experience)

  17. ABRUPT, EXCESSIVE AND UNCOORDINATED CYCLIC CONTROL INPUTS SIDESLIP AFT CENTER OF GRAVITY LESS THAN 1G FLIGHT RESULT: LARGE ROTOR FLAPPING ANGLES - HUB TO MAST CONTACT POSSIBLE MAST BUMPING - CAUSES & AVOIDANCE

  18. HELISAS HeliSAS – R44 Installation • 12 Pounds • Approximately $30,000 • Two Servo-actuators, Cockpit switches and Gyro Package * - Pictures and system description, <http://www.helisas.com> [12 Sep 2005]

  19. IT REMAINS PUZZLING WHY HANDLING QUALITIES HAVE NOT BEEN PINPOINTED AS ACCIDENT CAUSES OR FACTORS A SIGNIFICANT NUMBER OF THE ACCIDENTS STUDIED COULD HAVE BEEN PREVENTED BY IMPROVED HANDLING QUALITIES THE INFERENCE IS THAT A SIGNIFICANT REDUCTION IN ACCIDENTS, INJURIES, AND PROPERTY DAMAGE COULD BE ACHIEVED BY THE INTEGRATION OF STABILITY AUGMENTATION SYSTEMS INTO THE CONTROL SYSTEMS OF THE LOWER PRICED HELICOPTERS CONCLUSIONS

  20. THE FEASIBILITY OF INCORPORATING LOW COST, LIGHT WEIGHT STABILITYAUGMENTATION SYSTEMS SHOULD BE EXPLORED BY HELICOPTER MANUFACTURERS REPRESENTATIVE CLASSES OF LIGHT PISTON AND TURBINE POWERED HELICOPTERS SHOULD BE EVALUATED BY THE GOVERNMENT TO ASSESS AND DOCUMENT HQ DEFICIENCIES RECOMMENDATIONS

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