Landing Gear, Aircraft Fuel Systems - Lec 4

7/29/2019 Landing Gear, Aircraft Fuel Systems - Lec 4

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Resource personAli Khalid

Department of Aviation Management & Technology

Superior University, Lahore.


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By the end of this session , you will be able to:

Understand the basics of aircraft landing system .

Understand the operation of retraction .

Understand about the aircraft fuel system

Understand about the aircraft instruments


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The undercarriage or landing gear in aviation, is thestructure that supports an aircraft on the ground andallows it to taxi, takeoffand land.

Typically wheels are used, but skids, skis,floatsor acombination of these and other elements can bedeployed, depending on the surface.

Landing gear usually includes wheels equipped withshock absorbers for solid ground, but some aircraft areequipped with skis for snow or floats for water.
http://en.wikipedia.org/wiki/Wheelhttp://en.wikipedia.org/wiki/Shock_absorberhttp://en.wikipedia.org/wiki/Skihttp://en.wikipedia.org/wiki/Seaplanehttp://en.wikipedia.org/wiki/Seaplanehttp://en.wikipedia.org/wiki/Skihttp://en.wikipedia.org/wiki/Shock_absorberhttp://en.wikipedia.org/wiki/Wheel


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The undercarriage is a relatively heavy part of thevehicle, it can be as much as 7% of the takeoff weight,but more typically is 4-5%.


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Three basic arrangements of landing gear are used: tailwheel type landing gear (also known as conventionalgear), tandem landing gear, and tricycle-type landing

gear.


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Tail wheel-type landing gear is also known asconventional gear because many early aircraft use thistype of arrangement.


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The main gear are located forward of the center ofgravity, causing the tail to require support from a thirdwheel assembly.

The increased clearance of the forward fuselage offered

by tail wheel-type landing gear is also advantageouswhen operating in and out of non-paved runways.


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Few aircraft are designed with tandem landing gear.

As the name implies, this type of landing gear has the

main gear and tail gear aligned on the longitudinal axisof the aircraft.

Sailplanes commonly use tandem gear, although many

only have one actual gear forward on the fuselage witha skid under the tail.


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A few military bombers, such as the B-47 and the B-52,have tandem gear, as does the U2 spy plane.

The VTOL Harrier has tandem gear but uses smalloutrigger gear under the wings for support.


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The most commonly used landing gear arrangement is

the tricycle-type landing gear.

It is comprised of main gear and nose gear.


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Tricycle-type landing gear is used on large and smallaircraft with the following benefits:

1. Allows more forceful application of the brakes withoutnosing over when braking, which enables higherlanding speeds.

2. Provides better visibility from the flight deck,especially during landing and ground manoeuvring.


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The tricycle-type landing gear arrangement consists ofmany parts and assemblies. These include air/oil shockstruts, gear alignment units, support units, retraction

and safety devices, steering systems, wheel and brakeassemblies, etc. > F-16 lg


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Multiple wheels spread the weight of the aircraft over alarger area.

They also provide a safety margin should one tire fail.

Heavy aircraft may use four or more wheel assemblieson each main gear. When more than two wheels are

attached to a landing gear strut, the attachingmechanism is known as a bogie.


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In addition to supporting the aircraft for taxi, the forcesof impact on an aircraft during landing must becontrolled by the landing gear. This is done in two ways:

1. The shock energy is altered and transferredthroughout the airframe at a different rate and timethan the single strong pulse of impact.

2. The shock is absorbed by converting the energy intoheat energy.


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259 faa


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An aircraft fuel systemallows the crew to pump and,manage, and deliver fuel to and the propulsion systemof an aircraft.

At the onset of aviation aircraft fuel systems wereremarkably simple affairs.

Fuel was gravity fed to the engine in most cases thoughhigher performance engines would have an engine-

mounted fuel pump.

Higher performance gave rise to more complexity withinthe fuel system.


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Therefore the need for transfer and booster pumpsaccompanied the arrival of high-performance aircraft.

More complex tank configurations introduced the needfor multi-valve systems such that the flight crew couldmove fuel around the fuel tanks according to the needsat the time.

Fuel systems differ greatly due to different performanceof the aircraft in which they are installed.


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A single engine piston aircraft will and have a verysimple fuel system, while a tanker (such as the KC-135)in addition of managing its own fuel can also provide

fuel to other aircraft


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Civilian

Jet A frz pt (-40 c) Jet A-1 frz pt( -47 c)

Jet B ( 30 %-70%,-60c)

Military

JP-4 similar to B JP-5 used in carriers

JP-8 similar to A1


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The fuel system is designed to provide an uninterruptedflow of clean fuel from the fuel tanks to the engine.

The fuel must be available to the engine under allconditions of engine power, altitude, attitude, and duringall approved flight manoeuvres.

Two common classifications apply to fuel systems in small

aircraft: gravity-feed and fuel-pump systems.


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The gravity-feed system utilizes the force of gravity totransfer the fuel from the tanks to the engine.

For example, on high-wing airplanes, the fuel tanks areinstalled in the wings.


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This places the fuel tanks above the carburettor, and thefuel is gravity fed through the system and into thecarburettor.

Carburettor is a device that blends air and fuel for aninternal combustion engine.
http://en.wikipedia.org/wiki/Earth's_atmospherehttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Earth's_atmosphere


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If the design of the aircraft is such that gravity cannot beused to transfer fuel, fuel pumps are installed.

For example, on low-wing airplanes, the fuel tanks inthe wings are located below the carburettor.


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Aircraft with fuel-pump systems have two fuel pumps.

The main pump system is engine driven with anelectrically driven auxiliary pump provided for use in

engine starting and in the event the engine pumpfails.

The auxiliary pump, also known as a boost pump,provides added reliability to the fuel system.


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A transport category aircraft fuel distribution subsystemconsists of the pressure fuelling components, defuelingcomponents, transfer system, and fuel jettison or dump

system. Single-point pressure fuelling at a fuelling station is

done by refuelling truck allows all aircraft fuel tanks tobe filled with one connection of the fuel hose.


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Occasionally, defueling the aircraft is required for aninspection or repair. The same fuelling station is used,and the hose from the fuel truck is connected to same

receptacle used to fuel the aircraft.


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The fuel transfer system is a series of plumbing andvalves that permits movement of fuel from one tank toanother on board the aircraft.

In-tank fuel boost pumps move the fuel into a manifoldand, by opening the fuel valve (or refuelling valve) forthe desired tank, the fuel is transferred


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Some aircraft fuel subsystems allow for fuel:

Jettison

Heating

Cross-Feeding


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The fuel jettison system comprises a combination offuel lines, valves, and pumps provided to dump fueloverboard during an in-flight emergency

This will reduce the weight of the aircraft so anemergency landing is possible


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Military aircrafts jettison their extra fuel when they arein close combat ( dog fight).


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Fuel heating is necessary for turbine enginesto thaw ice particles in the fuel that wouldotherwise clog the filters

Fuel is routed through a heat exchanger that

uses either engine oil or compressor bleed airto bring the fuel up to an acceptabletemperature.


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Cross feed systems allow the flow of fuel from any ofthe tanks to any of the engines.

Some reasons that this system might be used are:

Engine failure

Problem with one or more fuel tanks

Redistribute fuel for weight and balance purposes


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Most civil aircraft have a fuel tank configuration asshown


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The Fuel Management & Quantity Gauging System(FMQGS) for the Bombardier Global Express is typical ofa family of systems which may be found fitted to

regional aircraft and business jets.


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The Global Express has a trueintercontinental range capability approaching

6,000 mi and is cleared to 51,000 ft.

The heart of the system is the dual channel

FMQCG which embraces the followingfunctions.


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The fuel management function provides the following:

Control, status and built-in test (BIT) of all system

pumps, valves and pressure sensors.

Fuel transfer burn sequence and lateral balance.

Flight crew and ground crew interface.

Automatic/manual refuel/defuel operation.


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The Boeing 777 in contrast uses an integratedarchitecture based upon A429 and A629 data buses.

Fuel management system of boeing 777 emphasizingthe refuel function which is controlled via the ElectricalLoad Management System (ELMS)

There are six refuelling valves, marked as R on the nextslide


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The P310 panel provides power to the FQPU, integratedrefuelling panel and controls the operation of therefuelling valves.

This system permits the automatic refuelling of theaircraft to a preset value, as the FQPU senses the fueltank quantities reaching their assigned value, messages

are sent to the ELMS to shut off the refuelling valvesuntil all three tanks have attained the correct level.


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The FQPU is a multi-channel multi-processorcontroller which processes the fuel quantityinformation.

provided by a total of 52 tank units (probes), four waterdetectors and three densitometers located in the threefuel tanks.

The Boeing 777 uses ultrasonic fuel probes, the first civilairliner to do so.


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What is an instrument ???

A mechanical implement or tool, esp one used forprecision work.

In other words we can say that we use instruments (ofany type) to measure something more accurately?

Any example ?


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Thermometer is an instrument?

Yes, because we measure temp through

It more precisely

Similarly watch is also an instrument usedFor measuring time.


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The use of instruments as an aid to flight enables thepilot to operate the airplane more precisely, andtherefore, obtain maximum performance and enhanced

safety.

This is particularly true when flying greater distances


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Since the beginning of manned flight, it has beenrecognized that supplying the pilot with informationabout the aircraft and its operation could be useful and

lead to safer flight.

The Wright Brothers had very few instruments on their

Wright Flyer, but they did have an engine tachometer,an anemometer (wind meter), and a stop watch.


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From that simple beginning, a wide variety ofinstruments have been developed to inform flight crewsof different parameters. Such as altitude, heading etc

Instrument systems now exist to provide information onthe condition of the aircraft, engine, components, the

aircrafts attitude in the sky, weather, cabinenvironment, navigation, and communication.


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various instrument panels from the Wright Flyer to amodern jet airliner


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There are usually two parts to any instrument orinstrument system.

One part senses the situation and the other partdisplays it.

In analog instruments, both of these functions often

take place in a single unit or instrument. These are calleddirect-sensing instruments.


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Remote-sensing requires the information to be sensed,or captured, and then sent to a separate display unit inthe cockpit.


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The relaying of important bits of information can bedone in various ways :

Electricity is often used by way of wires that carrysensor information into the cockpit.

pneumatic lines are used.


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Landing Gear, Aircraft Fuel Systems - Lec 4

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Transcript of Landing Gear, Aircraft Fuel Systems - Lec 4