1Topic 2.17 Crash dynamics AVMO 0019 study cards

  1. Learning Outcomes?
    • • Describe factors that influence the body's tolerance to short duration accelerations.
    • • Summarize the principles of crash-worthiness that increase crash survivability.
    • • Describe the advantages and disadvantages of common types of restraint systems.
    • • Demonstrate how to adopt an appropriate ‘brace position".
    • • Describe ways to protect the head in an impact.
    • • List the features and functions of the aircrew helmet.
    • • Describe the effects of short duration acceleration on the body.
    • • Describe the accident survivability potential of aviation platforms based on principles of crashworthiness and use of PPE.
  2. “Short Duration” Acceleration?
    • • Acceleration acting upon the body for duration of less than half a second
    • • collisions
    • • ground impact
  3. Factors Affecting Human Tolerance?
    • • Magnitude of force
    • • Duration
    • • 45G in 0.04s or
    • • 25G in 0.2s
    • • Rate of onset (Jolt)
    • • Direction of applied force
    • • +Gx>-Gx>+Gz>-Gz>Gy
    • • Site of application
    • • Back/buttocks > head/limbs
  4. ‘CREEP’ factors?
    • Container
    • rigid protection of the occupants
    • Restraint
    • harnesses
    • seat strength
    • Environment
    • the “flail zone”
    • Energy attenuation
    • breakup pattern
    • size of the aircraft
    • Post-crash factors & escape
  5. “C” is for?
    • Container
    • the “Roll Cage”
    • Container
  6. “R” is for Restraint Systems?
    • • The ideal restraint system is:
    • • Comfortable
    • • Efficient (it works as advertised)
    • • Easy to use
    • • Causes minimal restriction
  7. 2 Point Harness (Lap Belt)?
    • • Advantages:
    • •Easy to use
    • •Minimal restriction
    • •Only 2 anchor points
    • • Major disadvantages:
    • Upper body restraint
    • more serious injuries
    • Submarining
    • Brace Position
    • Head down and hug knees
  8. 3 Point Harness?
    • • Advantages:
    • • Better upper body
    • • Disadvantages:
    • • Minimal lateral restraint
    • • Submarining
  9. 4 Point Harness?
    • • Advantages:
    • •Good upper body restraint
    • •Good lateral restraint
    • • Disadvantages:
    • •Submarining still
    • • possible
    • •Negative G
  10. 5 Point Harness?
    • • Advantages:
    • • The best type of restraint
    • • Negative G protection
    • • No submarining
    • • Disadvantages:
    • • No head / limb restraint
  11. Problems with restraints?
    • • Low takeoff point
    • • tight
    • • thoracic fractures possible
    • • Dynamic overshoot
  12. Low take off point?
    Compression Fracture
  13. Dynamic Overshoot?
    • • Harnesses not securely tightened
    • • Due to
    • • air gap
    • • elasticity of materials and body tissues
    • • Exaggerated high-peak deceleration
    • • Increased injury
  14. Dynamic Overshoot?
  15. “E” is for?
    Environment
  16. Delethalisation of the Flail Zone?
  17. “E” is for ?
    • Energy Absorption
    • Crumple Zones
    • Energy Absorption in Seat Design
  18. “P” is for Post-Crash Factors?
    • • Fire
    • •fire retardant materials, fire extinguishing systems, smoke hoods
    • • Exits
    • number and location, exit signs, floor/ emergency lighting, structural damage to exits, fire in vicinity blocking exit, slides, proximity to ground
    • • Orientation/location of aircraft
    • •submersion, inverted attitude, darkness
    • • Survival equipment
    • •life jackets, rafts, beacons, first aid equipment
    • •Water and food
    • • Injuries
    • •may prevent escape
  19. Post-Crash Factors?
  20. HELMETS & HEAD INJURY?
    • Head Protection
    • • Restraint system cannot fully protect from head injury
    • • Therefore must rely on:
    • • Rearward facing seats
    • • Survival space
    • • Helmets
  21. Head Injury?
    • • 40 % of injuries
    • • 20% of fatalities
    • • Skull fractures
    • • Primary brain injury
    • • Secondary brain injury
    • • Diffuse lesions
    • •“Concussion”
    • • Scalp/facial injuries
  22. Head Injury Prevents Escape?
    • • Head injury & unconsciousness can cause death in an otherwise survivable crash from:
    • • Fire
    • • Drowning
    • • Hypothermia
    • • Unable to escape and evade
  23. • A dent of up to 12.5mm in the cranium does not cause fracture or permanent injury?
  24. Helmets do many things?
    • • Protection from impact and penetration
    • • Eye protection
    • • Face/windblast protection
    • • Hearing protection
    • • Fire protection
    • • Mounting ancillary items
    • - Oxygen mask
    • - Comms equipment
    • - NVG, HMD, FLIR
  25. Helmets Prevent Head Injury?
    • • Helmets designed using CREEP principles
    • • Rigid container
    • • Restraints
    • • Energy attenuation
    • • Limits force to the skull
    • • Occupants remain conscious
    • • Less serious injuries
    • • Occupants remain conscious
    • • Increases chance of escape and thus survival
  26. How does a helmet work?
    • • Hard outer shell
    • • Rigid container
    • • Energy attenuation
    • • Stiff foam liner
    • • Spreads the load of impact
    • • Shell and liner
    • • Provides stopping distance
    • • 15mm
    • • Reduces 500G to 83G impact
  27. Effect of Stopping Distance?
    • • Stopping distance determines peak acceleration
    • • More distance reduces G to the head
    • • No helmet;
    • • distance = 3mm, G = 1700G FATAL
    • • With helmet;
    • • distance = 30mm,G = 170G SURVIVABLE
  28. Helmet Functions Impact Protection?
    • • Attenuation of energy*
    • • Resist rotary forces
    • • Avoid dynamic overshoot
    • • Protect against penetration*
    • • Must stay on during impact*
    • • MUST BE FITTED AND WORN CORRECTLY
  29. Helmet Functions Impact Protection?
    • • Cracking of the shell absorbs impact energy
    • • Deformable foam absorbs impact energy (& inc. s)
    • • This helmet is not defective
    • • it functioned as designed
  30. Helmets Protect Eyes?
  31. Visors down protect from?
    • • Bird strike
    • • Canopy fragmentation
    • • Windblast on ejection
    • • Glare and UV
    • • Flash fire
  32. The Ideal Helmet?
    • • Optimum weight, size, shape, C of G
    • • Smooth
    • • Comfort
    • • Good fit
    • • Ease of use
    • • Good visibility
  33. ALPHA Series?
    • • Advantages
    • •High Impact Protection
    • •HMD
    • •Dual Visor
    • •Good Stability & Retentivity
    • • Disadvantages
    • •Fit
    • •NVGs - Visors
    • •Weight
    • •Oxygen Mask
    • •No Ventilation
    • •External Clutter
    • •Difficult to Maintain
  34. HGU 56P
    • • Advantages
    • •Lightweight
    • •Impact Protection
    • •Comfort - Moulded liner
    • •Stability
    • • Disadvantages
    • •Size
    • •Weight

    • HGU 55P
    • • Advantages
    • •Lightweight
    • •Dual Visor
    • •Moulded Liner
    • •Good Stability and Retentivity
    • •Comfortable
    • •Easy to Maintain
    • • Disadvantages
    • •Limited Impact
    • Protection
    • •Lose visor during ejection
  35. Take home message…?
    A helmet must be fitted and worn correctly to do its job !
  36. Quiz question 19:?
    • The best negative G restraint is provide by which harness type:
    • a. 2 point b. 3 point c. 4 point d. 5 point
Author
david_hughm
ID
328894
Card Set
1Topic 2.17 Crash dynamics AVMO 0019 study cards
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1Topic 2.17 Crash dynamics AVMO 0019 study cards.txt
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