Module 4 ulit Flashcards
any undesirable or unwanted sound
noise
In the ______, the first-generation jet aircrafts led to a rapid expansion in commercial aviation with their ______ creating significant noise which severely disrupted the living patterns in nearby communities.
1950s, engines
In the ______, the U.S. Federal Aviation Administration (FAA) introduced the first noise certification standards and the International Civil Aviation Organization (ICAO) promoted similar standards globally (Smith, 1989).
1970s
What is Annex 16?
Environmental Protection
defined noise standards for aircraft certified before October 6, 1977
Annex 16 Chapter 2
defined noise standards for aircraft certified between October 6, 1977 and December 31, 2005
Annex 16 Chapter 3
defined noise standards for aircraft certified after December 31, 2005
Annex 16 Chapter 4
corresponds to ICAO Chapters 2/3/4
US FAR Part 36 Stages 2/3/4
Each new ICAO chapter imposes increasingly stringent noise limits, resulting in a ____ to ____ cumulative reduction in allowable noise.
10 to 20-dB
Two General Sources of Aircraft Noise
engines, airframe
Aviation Noise Sources
turbofan engine noise, turboprop engine noise, airframe noise, engine noise
It comes from the flow of air through and rapid rotations of the various components of the engine fan and core elements, as well as the high-speed gases in the engine exhaust being expelled into the outside air.
Turbofan Engine Noise (including APU noise)
This includes the turbulent air shed from each blade and the interactions between the blades.
Turboprop (Propeller) Noise
It is caused by the flow of air over the surfaces of the aircraft and the turbulent flows created by the structure and cavities introduced by the deployment of high-lift devices and landing gear.
Airframe Noise
It tends to dominate on the ground, especially during takeoff when the engines are at very high thrust level, on landing when using thrust reversers and when taxiing at low speed.
Engine Noise
It is created when the aircraft is flying at supersonic speeds which can be very disruptive to activities on the ground.
Sonic Boom
This issue severely limited the market for supersonic commercial aircraft introduced in the 1970s.
Sonic Boom
Only the ________ found a niche market serving transatlantic routes until its retirement in 2003 on economic grounds.
Aerospatiale-BAC Concorde
It is the ratio between the amount of air drawn in by the fan that bypasses the engine core relative to that passing through the core.
Bypass Ratio
Bypass ratio of large modem turbofan engines
10:1
This configuration achieves a given thrust level with minimum size of core and the slower moving bypass air mixes with the high-speed core air, resulting in a significantly lower exhaust velocity that in turn reduces exhaust noise.
large modem turbofan engines
near-term suggested solutions
engine core, nacelle chevrons, streamlined landing gear fairings
medium-term suggested solutions
geared turbofans, ultrahigh bypass ratio engines (unducted fan)
long-term suggested solutions
more integrated airframe/engine designs such as blended-wing body configurations
transmitted from a source through the air in waves
sound
It is sensitive to sound pressure.
human auditory system
The loudest sound a normal person can hear is approximately ____ times the RMS sound pressure of the faintest sound noticeable.
1 million
Its functions are:
- To address the limitations of using unweighted sound pressure levels in assessing the impact of noise on human perception and well-being.
- To provide a more accurate representation of how humans experience noise
The A-Weighted Sound Level
defined as a scalar quantity used to indicate the amplitude level of sound at a specific location in space
sound pressure
It is the deviation from the ambient atmospheric pressure and is caused by a sound wave
sound pressure
depends on the distance the measurement is taken from and in what atmospheric environment it is taken in
sound pressure
are not a unit of measure but a logarithmic function which indicates the ratio between two values
decibels
when the range of the sound pressure is expressed in decibels it is referred to as ______
sound pressure level
refers to the assessment and management of the impact of aircraft noise on the surrounding land uses
Aircraft Noise and Land-Use Compatibility
Two types of effects of noise on people
behavioural effects, health or physiological effects
One of the primary effects of aircraft noise is its tendency to drown out or mask speech, making it difficult or impossible to carry on a normal conversation without interruption. What is this called?
Speech Interference
Conversations may not require hearing every word; __% intelligibility is often acceptable, but __% is preferred for relaxed conversations.
95%, 100%
The disruptive effects of noise on sleep
sleep interference
lead to increased probabilities of sleep disruption
higher Sound Exposure Levels (SEL)
What does SEL stand for?
Sound Exposure Levels
What does DNL stand for?
Day-Night Average Sound Level
refers to the quietest sound that a person could hear
threshold shift
It is known that excessive exposure to loud noise can temporarily increase a person’s threshold shift but continued exposure to this can cause permanent hearing impairment. What is this called?
Noise-Induced Hearing Loss
has become the accepted standard for evaluating community noise exposure and helps in decision making regarding the compatibility of alternative land uses
Day-Night Average Sound Level (DNL)
In FAR Part 150, the FAA has established DNL as the _________ for use in airport noise analyses.
official cumulative noise exposure metric
All land uses are considered compatible with aircraft day night average sound levels below __ dB
65
Prediction using computer-based simulation models
The Integrated Noise Model (INM), Noisemap
offer opportunities for controlling ground-based noise sources such as takeoff and landing roll, taxiway and apron movements, aircraft power-backs. auxiliary power units, and maintenance engine runs
noise barriers
are walls, earth berms or wall-berm combinations
typical barriers
For ________, a barrier is often in the form of a pen or series of walls.
maintenance runups
Along the ______, especially in the vicinity of start takeoff roll, barriers are most effectively placed near the residences they are meant to protect.
runway sideline
can be degraded by temperature inversions and winds with a component blowing in the direction of source to receiver
barrier performance
of structures seeks to improve the environment indoors through treatment of the structure itself
sound insulation
With windows _____ the noise reduction properties of other parts of the structure are largely irrelevant and a noise reduction up to ___ is all that can be expected.
open, 14 dB
In order to be effective during the summer months, ________ must also be part of a basic noise insulation package so proper ventilation can be achieved with windows closed.
central air conditioning
Enhancing ________ can provide additional benefit once the aforementioned items are no longer the weak link.
roof and wall weight
it is based on optimizing runway utilization under wind, weather, demand, and airport layout constraints to minimize population impacts by taking advantage of uneven population distributions around the airport
preferential runway concept
The FAA has developed a recommended noise abatement takeoff procedure involving power settings and profile characteristics for turbojet-powered aircraft with maximum certificated gross takeoff weights in excess of _____ lb.
75,000
The objectives of the _________ program are the ensure that jet aircraft noise abatement procedures are safe, standardized and uncomplicated while at the same time being effective at reducing noise levels in the community.
National Business Aircraft Association
address noise control through reductions in the average noisiness of the aircraft that use the airport
noise-based airport use restrictions
designed to reduce or eliminate noisy operations during late-night hours when people may be particularly sensitive to noise
curfews
have been found to be overbroad and to impose undue burden on interstate commerce, and are often viewed as arbitrary and capricious
full curfews
provide an economic incentive to discourage the operation of noisier aircraft, especially during noise sensitive times of the day
noise-based landing fees
These are the highest level of regulations and are published in Title 14 of the Code of Federal Regulations (14 CFR).
Federal Aviation Regulations (FAR)
These are procedures that the FAA staff must follow, and they also apply to airports and airlines when they’re getting approval from the FAA.
orders
These are documents that provide guidance and information about the FARs and FAA orders. They are not mandatory but can help understand the regulations.
Advisory Circulars
specific regulation that applies to aircraft noise; sets different noise standards for different types of airplanes; outlines how aircraft noise is measured for certification purposes
FAR part 36
regulation started in ____ for big jetliners and propeller planes over ____ pounds
1969, 12,500
defines how airplane noise is measured during the certification process
FAR Part 36
These were around before the regulation even existed, so they don’t meet any specific noise limits.
Stage 1 Aircraft
those that met the original noise emission limits established in 1969 but did not meet the revised and more stringent limits introduced in 1977; these aircraft are generally louder than Stage 3 aircraft
Stage 2 Aircraft
the newest and quietest types; these aircraft must meet the revised noise emission limits introduced in 1977; designed to be significantly quieter than Stage 1 and Stage 2 aircraft, thus minimizing noise pollution
Stage 3 Aircraft
sets noise limits for airplanes based on their weight
FAR Part 36
Measured 6,500 meters (about 4 miles) down the runway from where the brakes are released
during takeoff
Measured 2,000 meters (about 1.2 miles) from the beginning of the runway where planes touch down
during approach
Measured 450 meters (about 0.3 miles) from the center of the runway, at the point where the plane makes the most noise on the side (usually during takeoff)
on the sideline
limits noisy airplanes; phased out Stage 1 airplanes; pushed for quieter airplanes
FAR Part 91
Sets standards for figuring out how loud airplanes are and how that noise impacts people on the ground
FAR Part 150
2 main parts to a FAR Part 150 plan
noise map, noise reduction plan
basically a report card on how noisy an airport is and how it affects the surrounding area
Noise Exposure Map (NEM)
outlines what the airport will do to reduce noise pollution
noise reduction plan
parts of a noise map
airport noise, land use, compatibility issues
The second major element of the national noise policy enacted through the Airport Noise and Capacity Act of 1990
FAR Part 161
It establishes requirements that an airport operator must meet prior to promulgating any airport noise or access restriction on the use of Stage 2 or Stage 3 aircraft
FAR Part 161
FAR Part 161 stipulates that both types of restrictions may be developed through the FAR Part ___ process.
150
The benefit of using FAR Part 150 as a mechanism for developing a rule restricting airport access is the _______.
availability of federal funding
The major disadvantage of submitting Stage 2 restrictions to the FAA as part of the FAR Part 150 submission is that a formal submission will_____ which is otherwise not necessary under FAR Part 161.
invoke the approval process
