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Passenger Aircraft Environmental Control System

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

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  1. Passenger AircraftEnvironmental Control System Safety Analysis Presented By: Brian Cranley, Ali Dalal, Chris Hankins, Josh Martin

  2. Objective • 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

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

  4. Bleed Air Air Conditioning Ventilation & Distribution Pressure Regulation System Components boeing.com

  5. 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 ASHRAE

  6. System Description (cont.) • Ozone Converter Qdisassociates ozone to oxygen molecules Quses a catalyst such as palladium (Pd) Qup to 95% effective when new limcoairepair.com

  7. 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 ntsb.gov

  8. 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 boeing.com

  9. 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

  10. 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 boeing.com

  11. Analyses Performed • Preliminary Hazard Analysis (PHA) • Failure Mode & Effects Analysis (FMEA) • Fault Tree Analysis (FTA)

  12. 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

  13. PHA(cont.) • Bleed Air System QIP Valve Qtemperature sensor • Pressurization System Qregulator assembly Qrelief valve

  14. 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

  15. FMEA (cont.) • Bleed Air System QIP Valve Q temperature sensor • Pressurization System Qregulator assembly Qrelief valve • Auxiliary Oxygen Supply Qstorage tank Qfire protection

  16. 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

  17. Conclusions & Recommendations • Install redundant temperature sensors Qdownstream of precooler Qentrance to cabin • Add redundant valves Qdownstream of IP valve Qcabin relief valves

  18. 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

  19. C & R (cont.) • Frequent software upgrades • Detailed maintenance procedures

  20. Questions

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