Aircraft Environmental Control Systems
Aircraft Environmental Control SystemsCopyright Specific Range Solutions Ltd. 2010A Presentation of Current Systems and New DevelopmentsCarleton University AERO 4003 Lecture – November 9th, 2010Omer Majeed, P.Eng.
OutlineToday’s lecture is an introduction to aircraft Environmental Control Systems (ECS). Theobjective is to present a top level view of the systems, from regulatory requirements to thearchitecture and function of the individual systems. Some requirements and componentswill be addressed in more detail as examples. Summary of my education and career ECS definition and main applicable regulations Role of safety analysis in system design Bleed Leak Detection System function Air Conditioning System functions and architecture Cabin Pressurization Control System functions and architecture New technology developments in ECS: Boeing 787 Dreamliner Questions?2Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010 Bleed Air (Pneumatic) System functions and architecture
Education & Career SummaryEducation:Bachelor of Aerospace Engineering, Carleton University, 1992. First graduating class.Masters of Aerospace Engineering, Carleton University, 1995. Thesis topic was numericalmodeling of transverse impact on composite coupons.Transport Canada Commercial Pilot Licence and Multi-Engine Rating (2001).Career:Ingenia Communications (1995-1997).Liebherr-Aerospace (1999-2008) as air systems engineer in Toronto (GX, Q400), Wichita(CL300) and Toulouse (A380).Founded Specific Range Solutions Ltd. (2008) specializing in flight optimization solutions, aswell as air systems analysis and design (www.srs.aero).Professional Affiliations:Member of PEO since November 10th, 2000.Past member of AIAA (Wichita) and RAeS (Toulouse).Current member of executive of CASI Ottawa Branch.3Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010National Research Council’s Centre for Surface Transportation Technology (1997-1998).
ECS Definition and RegulationsEnvironmental Control Systems control the temperature, pressure and air flow into theaircraft pressure vessel which includes the cockpit (flight deck), cabin and interiorcompartments. Safety monitoring is also performed e.g. cabin altitude (ZC), cabin ΔP.Some of the main applicable regulations for ECS are per Transport Canada’s AirworthinessManual Chapter 525: 525.831 Ventilation 525.832 Cabin Ozone Concentration 525.841 Pressurised Cabins 525.1438 Pressurisation and Pneumatic SystemsAll aircraft systems must perform their intended function under any foreseeable operatingcondition and permit safe continuation of the flight after any failure i.e. fail-safe concept. 525.1309 Equipment, Systems, and InstallationsCopyright Specific Range Solutions Ltd. 2010On transport-category aircraft, ECS comprises various systems performing the followingfunctions: bleed air supply, bleed leak detection, air conditioning, distribution, avionicscooling, cabin pressurization control, oxygen supply. The trend today is towards increasingintegration of all air systems, including wing anti-ice/de-ice functions via a commoncontroller architecture. Two system control modes are typically provided on modern aircraftsystems: automatic (1 active 1 stand-by) and manual (back-up).
L/H WAI* The Boeing 737 Technical Guide, Chris Brady, Tech Pilot Services 20065Carleton University AERO 4003 Lecture – November 9th, 2010R/H WAICopyright Specific Range Solutions Ltd. 2010Boeing 737-300/500 ECS Schematic*
System Safety Analysis / Functional Hazard AssessmentSeverity(Failure Condition)NoneFAA ReferenceN/AEASA ReferenceAMC 25.1309 (No Safety Effect)AC 25.1309-1AAMC 25.1309 (Minor)AC 25.1309-1AAMC 25.1309 (Major)AC 25.1309-1AAMC 25.1309 (Hazardous)CatastrophicDefinitionNormal operationFailure conditions which would not significantly reduceairplane safety, and which involve crew actions that are wellwithin their capability.Failure conditions which would reduce the capability of theairplane or crew to cope with the adverse operatingconditions to the extent that there are significant reductionsin safety margins or functional capabilities.Failure conditions which would reduce the capability of theairplane or crew to cope with the adverse operatingconditions to the extent that there are large reductions insafety margins or functional capabilities.Failure conditions which would prevent continued safe flightand landing.AC 25.1309-1AAMC 25.1309 (Catastrophic)Probability(Failure Rate/Flight Hour)NoneProbableImprobable (i)Improbable (ii)Extremely ImprobableDefinitionNormal operationFailure 10E-510E-5/FH Failure 10E-7/FH10E-7/FH Failure 10E-9/FHFailure 10E-9FAA ReferenceN/AAC 25.1309-1AAC 25.1309-1AAC 25.1309-1AAC 25.1309-1AEASA ReferenceAMC 25.1309 (No Safety Effect)AMC 25.1309 (Probable)AMC 25.1309 (Remote)AMC 25.1309 (Extremely Remote)AMC 25.1309 (Extremely Improbable)MinorMajor (i)Major (ii)6Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010Hazard (Risk) Severity * Probability
Bleed Air System FunctionsThe Bleed Air System also known as the Pneumatic System supplies the air required by thedownstream consumers while regulating the pressure and temperature of the air from theengines to values of 45 psig and 200oC, respectively. The system also selects the engineport from which to bleed.Bleed air is supplied by the engines or the Auxiliary Power Unit (APU). Air is drawn from thecompressor stage, upstream of the combustor. APU bleed is typically used on the ground and permitted in flight up to a certainaltitude. On a cold day (-40oC), APU supplies air at 60 psig and 160o C on theground. On a hot day ( 40oC), it supplies air at 40 psig and 240oC.Engine bleed reduces thrust and increased fuel burn (SFC), the impact is a function ofsupply port (LP/IP or HP) and mass flow. Use of LP/IP bleed is preferred because ofreduced impact on fuel burn.Minimum pack pressure is in the range of 15 to 20 psig which requires a minimum portpressure of 23 psig. If LP port pressure is lower than minimum value, then HP port isselected via High Pressure Valve (HPV). A check valve prevents reverse flow into LP port.Bleed is extracted evenly from around the compressor to minimize downstream disturbanceof the core flow.7Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010 Engine bleed is typically used in flight. At take-off and ISA conditions, representativevalues are 85 psig and 280oC for an engine LP (Low Pressure) port and 200 psigand 420oC for the HP (High Pressure) port. Bleed temperatures can exceed 540oC.
Bleed Air System Functions and ArchitectureBleed pressure is controlled via a Pressure Regulating Valve (PRV) which typically includesreverse flow protection. Older systems feature pneumatic control via a downstreampressure tap, while more recent systems use electro-pneumatic control with reference to adownstream pressure sensor.Copyright Specific Range Solutions Ltd. 2010Bleed temperature is controlled via a Fan Air Valve (FAV) which modulates the fan (cold) airflow through the Precooler, an air-to-air heat exchanger. Legacy systems feature pneumaticcontrol via a thermostat. Current system design uses electro-pneumatic control withreference to a downstream temperature sensor.8Carleton University AERO 4003 Lecture – November 9th, 2010
A380 Pressure Regulating Valve Functions and DesignDESCRIPTION:6” diameter butterfly valve, pneumatically actuated,electrically controlled via solenoid & torque motor,commanded by the controller.ACTUATOR S/AFUNCTIONS:POSITION INDICATOR To balance the flow between adjacent EngineBleed Air Systems when Cross Bleed Valves areopen. To ensure shut-off function of the EngineBleed Air System e.g. in case of fire.TEST PORT INTAKEKEY COMPONENT OFBLEED SYSTEMSOLENOIDOPENINGCLOSINGCopyright Specific Range Solutions Ltd. 2010 To control pressure delivered to downstreamusers per system requirements.BUTTERFLYVALVE S/A9Carleton University AERO 4003 Lecture – November 9th, 2010
A380 Bleed Air System Synoptic PageHP VALVE POSITIONOpenClosed52Closed position disagreeXXPR VALVE POSITIONOpen43Closed3Position Data not AvailableClosed position disagreeXXPosition Data not AvailableEngine Bleed Temperature230Normal1XXTemperature data not available45110300Bleed Temperature Low / HighEngine Bleed Pressure11030040NormalXXPressure data not availableBleed Pressure Low / HighPneumatic Air Distribution System ATA36-12Copyright Specific Range Solutions Ltd. 20101
Bleed Leak Detection FunctionA bleed air leak is a fire risk e.g. max. allowable surface temperature to avoid fuel autoignition is 204oC per FAA AC 25.981-C. Bleed leak is also a risk to aluminum andespecially composite primary structure. Leak detection required via thermal switches (zonalsensors) or via continuous elements which are routed along bleed ducts.Leak detection loops are 1/8” dia. coaxial wires (inner conductor and outer shell) separatedby a high resistance eutectic salt calibrated to a specific melting temperature. When theloop is locally heated, the salt melts and a short results which changes the loop coaxialresistance. Resulting voltage change Leak detectionBleed leaks can also result in overpressure in compartments, so provision for blowoutpanels may also be required.11 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010Continuous elements are preferred due to coverage, integrity monitoring and they functionafter being cut (post-PBIT). They allow for the location of the event along the circuit. Dualloops are used in critical areas for redundancy and to minimize false leak warnings.
Air Conditioning System FunctionsThe Air Conditioning System (ACS) conditions the fresh air from the Bleed Air System andsupplies it to the cockpit and cabin zones at the requested mass flow rate. Conditioningrefers to the regulation of temperature and the removal of humidity. The system may haveprovision to recirculate a portion of the cabin air.System requirements: Supply adequate fresh air i.e. sufficient oxygen and remove odours. Temperature control within a comfortable range in each cabin zone [15oC - 35oC].The standard dynamic sizing case is a “pull-down” or cabin cooling case on the ground on ahot day with APU bleed: 40oC and 45% relative humidity (RH) at Sea Level. Interior temperature after heat soak is assumed to be 46oC. The requirement is to pull-down the cockpit and cabin temperature to 24oC in 30 min,with no passengers on board (minimum crew), and doors closed. 3oC is the normal minimum allowed (duct) temperature supplied to occupied zones.12 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010 Supply air for cabin pressurization i.e. sufficient outlet pressure.
525.831(a) Ventilation (CAR)Per Transport Canada’s Airworthiness Manual Chapter 525:525.831 (a)This is equivalent to 7.5 cfm at cabin altitude (ZC) of 0 ft and 10 cfm at ZC 8,000 ft.Cockpit flow is proportionately higher per occupant due to additional heat loads (avionics,displays, solar through windshield).CompartmentFlow to cockpit (%)Flow to cabin (%)Challenger (19 pax)4753CRJ100/200 (50 pax)2179CRJ700 (70 pax)1585For the Bombardier Challenger 605 which is certified for 19 passengers and a crew of 3, therequired normal airflow is 19.7 lb/min.13 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010(a) Under normal operating conditions and in the event of any probable failure conditions ofany system which would adversely affect the ventilating air, the ventilation system must bedesigned to provide a sufficient amount of uncontaminated air to enable the crew-membersto perform their duties without undue discomfort or fatigue and to provide reasonablepassenger comfort. For normal operating conditions, the ventilation system must bedesigned to provide each occupant with an airflow containing at least 0.55 pounds of freshair per minute.
525.832 Cabin Ozone Concentration (CAR)Per Transport Canada’s Airworthiness Manual Chapter 525:525.832 Cabin Ozone Concentration(a) The aeroplane cabin ozone concentration during flight must be shown not to exceed:(1) 0.25 parts per million by volume, sea level equivalent, at any time above flight level 320;and(2) 0.1 parts per million by volume, sea level equivalent, time-weighted average during any3-hour interval above flight level 270.(c) Compliance with this section must be shown by analysis or tests based on aeroplaneoperational procedures and performance limitation, that demonstrate that either:(1) The aeroplane cannot be operated at an altitude which would result in cabin ozoneconcentrations exceeding the limits prescribed by paragraph (a) of this section; or(2) The aeroplane ventilation system, including any ozone control equipment, will maintaincabin ozone concentrations at or below the limits prescribed by paragraph (a) of thissection.Why is there a regulation specifically for ozone? O3 can cause dryness of nose and throat,and itching of eyes. Long-range transports often install ozone converters (O3 - O2)14 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010(b) For the purpose of this section, "sea level equivalent" refers to conditions of 25 Cand 760 millimetres of mercury pressure.
ACS Steady-State Performance RequirementsSteady-state performance requirements are based on the sum of the various heat loads.List of heat loads: Latent heat emission by occupants Q lat is due to evaporated moisture (perspiration).Even if air is fully recirculated and Q lat does not enter into heat load, it influencesrelative humidity of the compartment. With recirculation, some of the moisturecondenses in the cooling system and is part of the heat load. For a person at rest in24oC surroundings 41 W. Internal electrical loads Qe is the heat generated by avionics, lights, galleyequipment, etc. These loads can be quite high; for example in the CRJ700 they areapproximately 3 kW. Reduction is possible if cooling air is ducted around theequipment and is discharged overboard. Solar heat load Qsol is transmitted through the windshield and windows. Conductive heat load Qc is due to heat transfer from outside the aircraft to the inside,by conduction and convection through structure, insulation, and airspaces.Total heat load for a CRJ700 in pull-down would be 26.3 kW.15 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010 Sensible heat emission by occupants Qsens is heat emitted by a person throughconvection and radiation and is dependent on compartment temperature and activitylevel. For a person at rest in 24oC surroundings 73 W.
ACS Steady-State Performance Requirements & Pack DesignPer the following equation, the system must remove or supply the required thermal power:Q W * Cp air * (Tc – Ts)W Mass flow in kg/sCp dry air 1.005 kW/[kg/s – K]Tc Cockpit/cabin target temperature in oCTs Supply temperature in oCACU’s are based on vapour cycle or air cycle. Early transport aircraft used vapour cyclewhich absorbs heat using a refrigerant. It is still used in some GA and business aircraft, aswell as helicopters. Also used in galley chillers and for military avionics cooling.Today all large transport aircraft use air cycle architecture where bleed air is expanded(cooled), pumped into the cabin and then dumped overboard.Advantages of air cycle systems are the refrigerant (air) is free, the compressor is alreadypart of the engine and APU though there is an SFC impact, air is directly used for cooling orheating therefore no evaporator required, efficient heat transfer, minor leakage is not aproblem and mechanically simple system. Therefore, lighter system weight, safer and morereliable.16 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010Air Conditioning Unit / Cooling Pack Design:
Air Conditioning System Pack DesignThere are three main types of air cycle machines: simple cycle (fan turbine), two wheelbootstrap (compressor turbine) and three wheel bootstrap (fan compressor turbine),the latter is the current industry standard.Bleed air from the APU (unprecooled) or from theengines (precooled) is boosted in pressure andtemperature by the compressor. This increasesthe efficiency of the heat exchange though thepack heat exchanger (HX). On the ground, the fandraws ram air to cool the bleed air while in flight,ram air does the pack cooling. The bleed air thenpasses through the turbine where it is expandedand flows into the cabin. The work extracted bythe turbine drives the shaft and thus thecompressor and fan.17 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010Three Wheel “Bootstrap” Cooling Pack (ACU):
Air Conditioning System Pack DesignThere is a need to extract water from the ACU to prevent condensation in the cabin (fog andwater droplets) and in the case of a high-performance pack, icing at the turbine outlet.There are two means to extract water: low-pressure separation and high-pressureseparation. This effectively reduces the humidity in the cabin.Low pressure separation is a simple system locateddownstream of the turbine outlet: Consists of a shell, fabric coalescer, baffles and adrain port Disadvantages: coalescer must be periodicallycleaned or replaced, and this system cannot beoperated at temperatures below freezing.High pressure separation requires a condenser HEXin the turbine discharge duct to cabin. The air fromturbine cools the bleed air (at high-pressure andtemperature) and this enables much of the bleed airmoisture to condense. The droplets are extracted viaswirling motion imparted to air. System is heavierand more costly, but more efficient and lessmaintenance is needed. Also, less turbine erosion.18 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010 Low weight and initial cost
Boeing 747-8 Air Conditioning PackPack Dual Heat ExchangerRam Air OutletReheaterBleed Air InletCondenserRam Air PlenumPack OutletAir Cycle Machine19 Carleton University AERO 4003 Lecture – November 9th, 2010Attachment FittingsCopyright Specific Range Solutions Ltd. 2010Water Extractor
Air Conditioning System Recirculation & DistributionRecirculation:Many transport aircraft use recirculation: 50/50 (% fresh air / % recirculated air) or 60/40.Enables colder air from pack (down to –29oC “Dry Air Rated”) to be mixed with warmer airfrom the cabin which results in a mix manifold temperature colder than cabin temperature.This reduced bleed demand and therefore fuel burn. Recirculation also promotes moreefficient cabin air extraction, thus circulation.There are concerns regarding the transmission of viruses and bacteria in aircraft usingrecirculation. Recirculation systems typically have filters to clean the cabin air: HEPA,activated charcoal, cold plasma, etc.Objective is to evenly distribute air throughout thecabin to minimize stratification and excessivetemperature variations in a zone. Low Pressure (LP) ducting is insulated to minimizeheat loss (either way), thermal mass and pressuredrop. Fuselage skin and floor are also insulated. Air should enter and leave the cabin uniformly.20 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010Distribution:
Global Express Air Conditioning System Architecture** Global Express IAMSMaintenance Training Guide21 Carleton University AERO 4003 Lecture – November 9th, 2010Copyright Specific Range Solutions Ltd. 2010Below is ACS architecture for the Global Express long-range business jet from the FlowControl V
controller architecture. Two system control modes are typically provided on modern aircraft systems: automatic (1 active 1 stand-by) and manual (back-up). Some of the main applicable regulations for ECS are per Transport Canada’s Airworthiness Manual Chapter 525: 525.831 Ventilation 525.832 Cabin Ozone Concentration 525.841 Pressurised Cabins
- B734 aircraft model added - B735 aircraft model added - E145 aircraft model added - B737 aircraft model added - AT45 aircraft model added - B762 aircraft model added - B743 aircraft model added - Removal of several existing OPF and APF files due to the change of ICAO aircraft designators according to RD3: A330, A340, BA46, DC9, MD80
F/A-18E/F Super Hornet Fighter 1,253.1 million (14 aircraft) 1,996.4 million (24 aircraft) V-22 Osprey Tiltrotor Aircraft 961.8 million (6 aircraft) 1,280.1 million (7 aircraft) C-130J Hercules Military Transport Aircraft 886.1 million (9 aircraft) 1,571.9 millio
A holding pattern is a shift by T This is the set in which we want to schedule aircraft. We seek one arrival time for each aircraft in each of the colored sets. aircraft 1 aircraft 2 aircraft 3 feasible arrival times aircraft aircraft 4 a1 b1 a2 b2 a3 b3 a4 b4 A holding pattern can be expressed as a MILP
Abandoned aircraft: Refers to the aircraft permanently parked without a storage maintenance program. In some cases, the aircraft has been deregistered and it may be impossible to identify the owner. Aircraft owner: In this manual, this term includes the person or organization that has control over whether an aircraft is to be sold or .
Systems Description (Section 7) This section describes the aircraft systems in a manner appropriate to the pilot most likely to operate the aircraft. For example, a manufacturer might assume an experienced pilot will be reading the information for an advanced aircraft. For more information on aircraft systems, refer to Chapter 6, Aircraft Systems.
The military installs and maintains aircraft arresting systems when certain military operations are authorized at civil airports. Aircraft arresting systems serve primarily to save lives by preventing aircraft from overrunning runways in cases where the pilot is unable to stop the aircraft during landing or aborted takeoff operations.
Goodyear, founded in 1898, has been producing aircraft tires since 1909 and retreading aircraft tires since 1927. With more than 90 years in the aircraft tire business, Goodyear is the world’s largest supplier of aircraft tires. Goodyear aircraft tires have been selected as original equipment on virtually all current U.S. military aircraft.File Size: 2MBPage Count: 24
California Interagency Mobilization Guide 321 2011 1 80 – AIRCRAFT 2 3 Table of Contents Pages 4 80 – AIRCRAFT 322 5 81 - AIRCRAFT INVENTORY 322 81.1 LEAD PLANES/6 AERIAL SUPERVISION AIRCRAFT (ASM) 322 81.27 - AIRTANKERS 323 81.3 –8 HELICOPTERS 324 81.3.1 FOREST SERVICE FIRE9 WATCH HELICOPTERS 325 81.4 - AIR10 ATTACK/TACTICAL AIRCRAFT 325File Size: 378KB
