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Passenger Aircraft Environmental Control System. Safety Analysis Presented By: Brian Cranley, Ali Dalal, Chris Hankins, Josh Martin. Objective. To analyze and perform a System Safety Analysis on Environmental Control Systems (ECS) in passenger aircraft

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Passenger aircraft environmental control system

Passenger AircraftEnvironmental Control System

Safety Analysis

Presented By:

Brian Cranley, Ali Dalal, Chris Hankins, Josh Martin


  • To analyze and perform a System Safety Analysis on Environmental Control Systems (ECS) in passenger aircraft

  • To derive possible redesigns in procedures and hardware involved in the functionality of the ECS


  • Focuses on the hazards involved in a passenger aircraft cruising at an altitude of 35,000ft

System components

Bleed Air

Air Conditioning

Ventilation &




System Components

System description
System Description

  • Bleed Air

    Q”heart” of the ECS

    Qautomatic aside from an

    on/off switch in cockpit

    Qcomprised of the engine,

    valves, ports, and sensors that allow airflow

    Qselects the right bleed port to send air through (dependant upon where the aircraft is, i.e. takeoff, cruise, or landing)

    Qdecreases the pressure and temperature of air entering the aircraft so it can be dispersed for the remainder of the ECS


System description cont
System Description (cont.)

  • Ozone Converter

    Qdisassociates ozone to

    oxygen molecules

    Quses a catalyst such

    as palladium (Pd)

    Qup to 95% effective when new

System description cont1
System Description (cont.)

  • Air-conditioning Packs

    Qair is dried to 10-20% humidity

    Qair is cooled from 400°F

    (temperature when leaving

    ozone converter) to 60°F

    Qmost commercial aircraft

    utilize two or three air-cycle

    machines linked in parallel

    as a safety precaution against

    in-flight failures

System description cont2
System Description (cont.)

  • Distribution and Filtration

    Qair from air-conditioner is

    mixed in manifold with

    filtered, re-circulated air.

    Qair is treated with a HEPA

    (high-efficiency particulate air)

    filter - nearly 99.9% effective

    in removing microbes

    Qair is distributed from manifold

    to ductwork, and then through vents at roughly 500 fpm

    Qair stays in cabin 2-3 minutes before it is re-circulated

System description cont3
System Description (cont.)

  • Backup Oxygen Supply

    Qin event of ECS system failure

    Qoxygen stored in container

    and valve assemblies at 1850psi

    Qreduced to 70psi for delivery

    through overhead masks

System description cont4
System Description (cont.)

  • Pressure Regulation

    Qdesired pressure altitude

    of 8000ft

    Qcabin controlled by

    pressure regulator

    Qlocated so that all cabin air

    must pass through the outflow

    valve section to return to the atmosphere

    Qregulator assembly recognizes the changes in ambient pressure and controls the inflow and/or outflow of air depending on controller signals

    Qsafety valve incorporated to reduce high cabin pressure

Analyses performed
Analyses Performed

  • Preliminary Hazard Analysis (PHA)

  • Failure Mode & Effects Analysis (FMEA)

  • Fault Tree Analysis (FTA)

Preliminary hazard analysis
Preliminary Hazard Analysis

  • PHA

    Qtakes place during the design phase

    Qreview of historical safety experience

    Qidentifies areas for concern

    Qidentifies and evaluates hazards

    Qbegins to consider safety design criteria

Pha cont

  • Bleed Air System

    QIP Valve

    Qtemperature sensor

  • Pressurization System

    Qregulator assembly

    Qrelief valve

Failure mode effects analysis
Failure Mode & Effects Analysis

  • FMEA

    Qreliability form of analysis

    Qmay contain events that will not contribute to an accident

    Qanalyzes system components for their contribution to a state of unreliability

Fmea cont
FMEA (cont.)

  • Bleed Air System

    QIP Valve

    Q temperature sensor

  • Pressurization System

    Qregulator assembly

    Qrelief valve

  • Auxiliary Oxygen Supply

    Qstorage tank

    Qfire protection

Fault tree analysis
Fault Tree Analysis

  • FTA

    Qmethod structures relations in a graphic representation to form a Boolean logic model

    Qstructured to end in a specific outcome

    Qdirects deductively to accident-related events

    Qcan be qualitative or quantitative

    Qprovides insight into system behavior

Conclusions recommendations
Conclusions & Recommendations

  • Install redundant temperature sensors

    Qdownstream of precooler

    Qentrance to cabin

  • Add redundant valves

    Qdownstream of IP valve

    Qcabin relief valves

C r cont
C & R (cont.)

  • Fire protection

    Qfire resistant materials

    Qinstall sprinkler heads

    Qsmoke hoods

  • Auxiliary Oxygen Supply

    Qexplosion resistant casing for storage tank

    QO2 sensors

    Qmanual O2 mask release

C r cont1
C & R (cont.)

  • Frequent software upgrades

  • Detailed maintenance procedures