40 Fuel System 2013-Color

8/13/2019 40 Fuel System 2013-Color

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(c) 2013 by Edy Suwondo 2

Fuel Properties

Fuel Properties


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AirworthinessRequirements

Airworthiness Requirements 25.951 General.(a) Each fuel system must be constructed and arranged to ensure a flow of

fuel at a rate and pressure established for proper engine and auxiliarypower unit functioning under each likely operating condition,including any maneuver for which certification is requested andduring which the engine or auxiliary power unit is permitted to be inoperation.

(b) Each fuel system must be arranged so that any air which is introducedinto the system will not result in -

(1) Power interruption for more than 20 seconds for reciprocating engines;

or(2) Flameout for turbine engines .(c) Each fuel system for a turbine engine must be capable of sustained

operation throughout its flow and pressure range with fuel initiallysaturated with water at 80 F and having 0.75 cc of free waterper gallon added and cooled to the most critical condition foricing likely to be encountered in operation.

(d) Each fuel system for a turbine engine powered airplane must meet theapplicable fuel venting requirements of part 34 of this chapter.

34 : "Fuel venting emissions" means raw fuel, exclusive of hydrocarbonsin the exhaust emissions, discharged from aircraft gas turbine enginesduring all normal ground and flight operations.


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Airworthiness Requirements 25.963 Fuel tanks: general.(a) Each fuel tank must be able to withstand, without failure, the

vibration, inertia, fluid, and structural loads that it may be subjected toin operation.

(c) Integral fuel tanks must have facilities for interior inspection andrepair.

(d) Fuel tanks within the fuselage contour must be able to resist ruptureand to retain fuel, under the inertia forces prescribed for theemergency landing conditions

(e) Fuel tank access covers must :

(1) All covers located in an area where experience or analysisindicates a strike is likely must be shown by analysis or tests tominimize penetration and deformation by tire fragments, low energyengine debris, or other likely debris.

(2) All covers must be fire resistant as defined in part 1 of this chapter.(f) For pressurized fuel tanks, a means with fail-safe features must be

provided to prevent the buildup of an excessive pressuredifference between the inside and the outside of the tank.

Airworthiness Requirements 25.953 Fuel system independence.Each fuel system must meet the requirements of 25.903(b)

by -(a) Allowing the supply of fuel to each engine through a

system independent of each part of the system supplyingfuel to any other engine; or

(b) Any other acceptable method.

25.954 Fuel system lightning protection.The fuel system must be designed and arranged to prevent

the ignition of fuel vapor within the system by -(a) Direct lightning strikes to areas having a high probability

of stroke attachment;(b) Swept lightning strokes to areas where swept strokes are

highly probable; and(c) Corona and streamering at fuel vent outlets.


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Airworthiness Requirements

25.981 Fuel tank temperature.(a) The highest temperature allowing a safe margin below

the lowest expected auto ignition temperature ofthe fuel in the fuel tanks must be determined.

(b) No temperature at any place inside any fuel tankwhere fuel ignition is possible may exceed thetemperature determined under paragraph (a) of thissection. This must be shown under all probable

operating, failure, and malfunction conditions of anycomponent whose operation, failure, or malfunctioncould increase the temperature inside the tank

FUEL STORAGEFunctional Requirements

Fuel used, e.g.:Kerosene (Carbon 8-16): Jet A (freezing -40C), Jet A-1(freezing -47C, plus antistatic), where Jet A-1 = JP-8Wide cut gasoline (naphtha, Carbon 5-15, cold weather):Jet B similar to JP-4

High flash-point kerosene Type JP-5 (Jet Propellant) AvTur (Aviation Turbine Fuel) similar to Jet B or JP-4 AvGas (Aviation Gasoline, for piston engine)

Suitable for fuel and additives (anti-oxidant, icing-inhibitors,corrosion inhibitors, etc.)

Useable fuel content for standard payload. Additional tank oncenter wing.

Operating envelope (altitude, temperature, speed)


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FUEL STORAGETank lay-out

To ensure continuous fuel supply toengine and APU under extreme conditions(manoeuvre, negative g) collector tank Effect on pitch and roll moments dividetank

Off-load effect to structure reserve fuelin outer wing tank.Fuselage mounted engine (maximize tankvolume)

Pitching Moment


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Rolling Moment

Flammability limits


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Flammability limitsFlammability limits refer to the range of compositions, for fixedtemperature and pressure, within which an explosive reaction is possiblewhen an external ignition source is introduced. This can happen even whenthe mixture is cold. Flammability limits are given in terms of fuelconcentration (by volume) at a specified pressure and temperature. Forexample, the lean flammability limit for Jet A (aviation kerosene) in air atsea level is a concentration (by volume or partial pressure) of about 0.7%.The rich flammability limit is about 4.8% by volume or partial pressure.Flammability limits are not absolute, but depend on the type and strength

of the ignition source. Studies on flammability limits of hydrocarbon fuelshave shown that the stronger the source of the ignition stimulus, the leanerthe mixture that can be ignited. Flammability limits also depend on the typeof atmosphere (for example, limits are much wider in oxygen than in air),the pressure, and the temperature of atmosphere.http://www.galcit.caltech.edu/EDL/public/flammability.html (10-05-2010)

Flammable Vapor

Zone


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Fuel Tank Inerting

Air Separation for Inertingusing On-Board Inert Gas

Generation System(OBIGGS)


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Lightning protection Aircraft zones: (sensitive) wingtip, tail,propeller, nacelle)No sharp or pointed objectsFlame arrester (heat sink)

Lightning protection


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Maximum temperature

Margin to AIT is 50 oCPossible source of heat:

Boostpump locked in dry tank Boostpump running in drytank Refuel valve solenoids continuously energizedUse of thermal fuse (max component temp. 175 oC).

Hot surface ignit ntemp., oC

Auto Ignit iontemp., oC

Wide-cut gasoline 495 240Kerosene 480 225MIL-H-5606 (Petroleum) 515 225MIL-H-83282 (Synthetic) 580 355

MIL-L-7808 (Engine Oil) 545 385

MinimumElectricalEnergy

(flammablevapor)


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Water in fuel tanksMaximum 30 ppm undissolved water duringrefueling (fig. next page)

Adverse effects:Refreezing on screens of jetpump andboostpump inlet, fine filters of engine and APULocking or damaging pump impellerIndication of FQIS faultBacteria and fungus strontium-chromatetabletsCorrosion poly-urethane coatings

Dissolvedwater


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Water Drain

Tank Ventilation


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Tank Ventilation

Fuel Quantity Indicating System (FQIS)

Ultrasonic probes, at the bottom, pulse-echoCapacitance probes: AC (prefered) or DC system

AC systems: informasi besarnya capacitancedisalurkan dalam modulasi voltase AC, karenaitu rawan Electro Magnetic Interference (EMI)

kabel coaxial rumit, mahalDC systems: Sinyal dari probe disearahkandengan rangkaian dioda kemudian dikirim keprosesor sbg sinyal DC analog. Sistem inikurang disukai karena perlu tambahankomponen dalam tangki dan keandalannyakurang, relatif sistem AC.


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Fuel Quantity Indicating System (FQIS)Capacitance System

Fuel Quantity Indicating System (FQIS)Fo-100


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Fuel QuantityIndicatingSystem (FQIS)Magnetic Level

Indicator

B737 Dipstick

Refuel/Defuel System


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Refuel/Defuel System

Cross Feed System


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Engine/APU Supply System

Embraer Fuel Supply Sub-System


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Fuel Transfer

C.G. Trim C.G. Trim and off-load effect

A340 Fuel System Control

40 Fuel System 2013-Color

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