Noise & vibration Flashcards
What is the difinition of sound ?
Mechanical energy transmitted by longitudinal pressure waves through an elastic medium
Which effect of noice is the main concern for aviation personel ?
Hearing loss
What’s the 3 measurable characteristics of noice ?
Frequency (Hz)
Number of oscillations per second - determines pitch
Intensity (dB)
Meassure of decibels
Duration (time)
Time of expostion
At what decibel does the eardrum rupture ?
160 dB
What’s the army noise criteria for continuous unprotected exposure
(dB + duration)
85 dB - 8 hours
Name the types of noice
Steady-state (continuous)
impulse
What are the 3 types of hearing loss associated with prolonged exposure to noice ?
Conductive, sensorineural, mixed hearing loss
Do all military aircraft exceed safe noise exposure limits ?
Yes
What does damping mean ?
Loss of mechanical energy in a vibrating system
When does the highest level of vibration occur in a rotary wing aircraft ?
During the translation flow effect
Noticeable during t/o and also but less when decelerating for landing
Name 4 sources of vibration ?
- increased IAS
- Turbulence (environmental)
- Cruise to hover and vice verca
- internal/external loading
What’s the effet of vibration on the human performance ?
Speech
Can be distorted
Vision
Helmets may vibrate and instruments may be hard to read
Manual coordination
pilot may over-control during turbulence and transition in flight
Simple task completion
What are the physical effects of vibration ? (short term)
Fatigue
Respiratory effects
Circulatory effects
Motion sickness
Disorientation
Pain
What are the physical effects of vibration ? (long term)
Raynaud’s disease
Hand-arm vibration syndrome
Back pain
Kidney/lung damage
How to reduce vibration effects ?
Good posture (circulation)
Systems that protects under turbulence
