(AD) Aviation Machinist Mate Week 2

Feed Cell

Deliver the fuel to the engine

Pressure Element Pump

Delivers a flow of oil to the points of lubrication under constant volume

Input Leads

Delivers input power from the aircraft electrical system, or from an external power source, to the transformer

Ignitor Leads

Delivers power to ignitor plugs

Lubrication Jets (Nozzles)

Directs oil onto bearings and / or gears May direct air / oil mist or solid spray

Oil Pressure Indicator

Displays oil pressure in pounds-per-square-inch (PSI)

Engine Temperature Indicator

Displays temperature in degrees Celsius or Fahrenheit

Fuel Flow Indicator

Displays the signal as fuel flow in pounds-per-hour (PPH)

Dump System

Dump excess fuel overboard

Systems / Components of the Engine Electrical System

Engine Speed Indicating System, Engine Temperature Indicating System, Fuel Flow Indicating System, Oil Pressure Indicating System and Engine Fire Detection System

Aircraft Fuel System Servicing Safety Precautions

Ensure aircraft, fueling unit, and fueling nozzle are properly grounded to prevent static electricity from igniting Position the fueling unit as far from as the hose will allow Do not conduct fueling operations within 100 feet of operating aircraft, operating airborne radio / radar equipment, or in the vicinity of any grinding and welding Ensure aircraft fuel vent mast is free of obstructions and that adequate fire fighting equipment is available 3 People are required for fueling : Man fire fighting equipment Man the fueling hose Man the fueling unit

Types of Fuel Cells

Feed Cells, Fuselage cells, and Integral (Wing) Cells

Engine Fire Detection System's Components

Fire Detection Element and Fire Warning Light

Handling Procedures

Follow the correct procedures and use the appropriate personal protective equipment (PPE) to prevent injury

Extreme High Temperature Grease

For high-speed applications such as a ball or roller bearings

Molybdenum Disulfide

For sliding steel surfaces

General Purpose Grease

For wheel bearings, and where compatibility with rubber is required

Aircraft Fuel System Components

Fuel Cells/Tanks, Aircraft Fuel Pumps, Strainers, Aircraft Fuel System Valves, Fuel Probes, and Fuel Drains

Fuel Flow Indicating System's Components

Fuel Flow Transmitter, and Fuel Flow Indicator

Boost Pump

Fuel flow to the engine-driven fuel pump. Submerged unit containing a centrifugal pump and an electric motor (USED WITH FEED CELL)

Lubrication System Pump Types

Gear Type and Gerotor

Types of Greases

General Purpose Grease, Extreme High Temperatures Grease, and Molybdenum Disulfide

Methods of Fueling Aircraft

Gravity and Pressure

Engine Ignition System's Type

High Energy Capacitor Discharge: Spark must be constant under varying conditions

Various oil and air inlets and outlets

Holes

APU Safety Control System can be shut down manually by actuating the APU control switch in the flight station / cockpit to the OFF position so that

In case of fire, the APU fire warning light in the flight station / cockpit illuminates Pulling the T-handle of the APU control switch arms the fire extinguisher and removes 28 volts DC from the control switch

Tachometer (RPM) Indicator

Indicates engine compressor rotor RPM in percent. It is located in the flight station / cockpit

Overload Indication (OL)

Indicates input is too large to display

Bearing Components

Inner and Outer Race, Cage, and Bearing

Engine Ignition System Components

Input Leads, Transformer (Exciter), Ignitor Leads, and Ignitor Plugs

Manually Operated Shut-Off Valves

Installed where it is desirable to shut off the fuel while it is being removed or replaced Closed to stop fuel flow in case of fire

Viscosity

Internal resistance of a liquid that tends to prevent it from flowing

Aviation Fuels Description

Jet propellant fuel is a type of highly refined kerosene and is clear or light straw in color

Types of Oil Seals

Labyrinth, Thread, and Carbon

Determines the number of bearings

Length, Weight, and Number of Rotors

Pressure Relief Valve

Limits maximum pressure where the valve opens, and returns the excess oil to the inlet side of the pump

MILSPEC #

MIL-PRF-23699

Gear-Type Pump

May be a dual or multi-element pump with a pressure relief

Gerotor-Type Pump

May be a single, duel, or multi-element pump with a pressure relief valve

Methods of Producing Dynamic Electricity

Mechanical, Chemical, Thermal, and Pressure

Aircraft Fuel System Maintenance Support Equipment

Multi-RAE 50, Multimeter, Explosive-proof lighting/flashlight, Portable purging equipment, and Breathing Air System

Electrical Test Equipment

Multimeter

NATO #

NATO O-156

Labyrinth

Non rubbing surface and controlled by bleed air

Oil Pressure Indicating System's Components

Oil Pressure Transmitter and Oil Pressure Indicator

APU Safety Control System shuts down automatically when

Oil Pressure falls below minimum specified limits, Turbine exceeds maximum RPM, and Maximum temperature is exceeded

Lubricants

Oils and Greases

Quality Assurance Procedures

Perform a Foreign Object Damage free check Installing the Panel in accordance with (IAW) the applicable publication

Cartridge Filter

Periodically removed and replaced

Types of Lubricating Oils

Petroleum and Synthetic

APU Assemblies

Power Section Assembly and Gearbox Assembly

Multimeter Digital Display Features

Power Up, Overload Indication (OL), and Low Battery Indicator

Lubrication System's Pumps

Pressure Element Pump, Scavenge Element Pump

Lubrication System Valves

Pressure Relief Valve, Check Valve, and Bypass Valve

Aircraft Fuel Subsystems

Pressurization System, Vent System, Dump System, and Pressure Fueling System / Defueling System

Pressurization System

Pressurize the aircraft fuel system for fuel transfer

Strainers

Prevent large foreign particles from entering the fuel system

Oil Seals Purpose

Prevent oil from escaping its normal path of flow

Oils

Primarily as a lubricant and must be free-flowing and provide cooling, cleaning, and prevent corrosion

JP-5 or NATO F-44

Primary fuel used. High flash point

Pressure

Produced by applying pressure to quartz, which will produce an electron flow Ex: A Watch

Thermal

Produced by joining two dissimilar metals and applying heat Ex: Thermocouple

Mechanical

Produced by rotating a magnetic field through another magnetic field Ex: A Grass Cutter

Chemical

Produced by surrounding two or metallic plates with a chemical electrolyte Ex: A Battery

Aircraft Fuel System Purpose

Provide a controlled means of receiving fuel from external sources and supply fuel from tanks and cells within the aircraft to the engine

Auxiliary Fuel System's Purpose

Provide a means of increasing the aircrafts fuel capacity. This is done through the use of external tanks

Pressure Fueling / Defueling System

Provides a means of pressure fueling / defueling on the ground

Ignitor Plugs

Provides and air gap for voltage arc

Engine Starting System's Purpose

Provides initial rotation to accelerate the engine to the point where ignition can be accomplished and sustained

Multimeter Test Leads

Red lead = Positive and Black lead = Negative

Lubrication Heat Exchanger's Purpose

Reduce temperature of oil by transmitting heat from the oil to another fluid (fuel or air)

Electrically Operated Shut-Off Valves

Referred to at gate valves Control fuel flow during refueling and fuel transfer

Lubrication System Filter's Purpose

Remove contamination from lubricants

Lubrication System Components

Reservoir / Oil Tank, Lubrication System Valves, Lubrication System Pumps, Lubrication System Filters Lubrication System Heat Exchangers, Lubrication Jets (Nozzles), and Oil Pressure Transmitter

Scavenge Element Pump

Returns oil from engine bearing and gear cavities back to the reservoir / oil tank

Fire Detection Element

Senses an overheat condition or fire and transmits a signal to the flight station / cockpit

Deaerator

Seperates air from oil returning to the oil tank

JP-8 or NATO F-34

Similar to JP-5 except lower flash point

Fuselage Cell

Soft, bladder-type cells, constructed from rubber

Explosive-Proof Lighting / Flashlight

Spark resistant lighting used to aid visibility

Carbon

Spring loaded seal

Greases

Stable and free from bleeding, non corrosive, and weather and water resistant

Forms of Electricity

Static and Dynamic

Transformer (Exciter)

Steps up the input voltage to the rated output voltage.

External Tanks

Store additional fuel Varies in size but holds 150, 300, 400 Mounted on pylons on the underside of wings and centerline of the fuselage Are streamlined and may be jettisoned

Reservoir / Oil Tank's Purpose

Stores the system's oil supply

Auxiliary Power Unit Purposes

Supplies bleed air (pneumatic power) for: (1) Main engine starting, which is available at the start bypass valve. (2) Aircraft air conditioning, which is available at the pneumatic power source outlet The APU also supplies electrical and hydraulic sources of power to operate selected aircraft systems, which are used: (1) During ground maintenance allowing the aircraft to be independent of support equipment (2) For emergency electrical and hydraulic power while in flight Additionally, the APU supplies mechanical power, which is available as shaft power at the main output drive pad

Engine Speed Indicating System's Components

Tachometer (RPM) Indicator and Tachometer Generator

Voltage / Electromotive Force (EMF)

The amount of force being applied to a circuit to produce an electron flow

Integral (Wing) Cells

The interior portion of the wing

Watt

The measurement of electrical work done

Ohms

The measurement of resistance to current flow

Resistance

The opposition to the flow of electrons offered by a device or material

Electricity

The physical phenomena arising from the existence and interaction of an electrical charge

Amperage / Current Flow

The quantity of electricity flowing through the circuit

Engine Temperature Indicating System's Components

Thermocouple Assembly and Engine Temperature Indicator

Engine Lubrication System's Purpose

To provide an adequate supply of clean oil to the bearings and gears at the right temperature and pressure

Types of Aircraft Fuel Pumps

Transfer Pump and Boost Pumps

Transfer Pump

Transfer fuel from various cells/tanks to the main tanks. May be either electrically driver or ejector type

Disposal Procedures Factors

Type and Location

JP-4 or NATO F-40

Used as an alternate fuel to JP-5. Lowest Flash Point out of the three and is the has the highest volatility

Petroleum

Used in reciprocating (piston) engines and is graded to identify the series and viscosity of the oil

Ball Bearings

Used on compressor and turbine shafts. Absorb both radial and axial loads

Roller Bearings

Used on high centrifugal force and aborb only radial loads

Fuel Level Control Valves

Used to control the level of fuel in the fuel cell/tanks

Aircraft Fuel Pumps Purpose

Used to deliver continuous supply of fuel to the engines

Multi-RAE 50

Used to detect fuel vapor levels

Fuel Drain

Used to drain condensation from the fuel system Drain excess fuel from the cells'tanks Drain samples for contamination checks

Fuel Probes

Used to transmit an electrical signal to the cockpit / flight station fuel quantity indicator to register the amount of fuel in the cells/tanks.

Thread

Uses reverse threading

Hazards of Jet Propellants

Vapors are highly toxic and explosive

Vent System

Vent fuel cells/tanks to prevent pressure build up

Reservoir / Oil Tank Components

Vent, Deaerator, Oil Level Transmitter, Coarse Mesh Screens, Various oil and air inlets and outlets

Types of Engine Lubrication Systems

Wet Sump and Dry Sump

Accessory Bearing

(1) Absorb loads created by drive shafts and gears (2) Allows accessory shafts and gears to rotate freely

APU Ignition System

(1) Capacitor discharge type that consists of an ignition exciter, ignitor lead, and ignitor plug

Static Electricity

(1) Electricity at rest (2) Begins with a build up of either a positive or negative electron charge. If two negative charges or two positive charges are brought close together, the objects that hold that charge repel each other. If a positive charge is brought within close proximity of a negative charge, the two objects attract each other (3) Static electricity is produced by friction and is not easily measured nor is it controllable or usable

Servicing the Lubrication System

(1) Engine oil shall be check and serviced within a specified amount of time after shutdown in accordance with appropriate technical manual (2) Aircraft must be on level ground to ensure the oil is not affected by aircraft attitude (3) Service the Engine Lubrication System in accordance with appropriate technical manual (4) The PON-6 pre oiler provides pressurized, filtered oil for servicing. It is a self-contained hand-operated12 quart system

APU Fuel System

(1) Fully automatic system (2) Supplies required fuel under all operating conditions (3) Receives its fuel from the the aircraft fuel system

Fuel Cell Entry Process (Before Maintenance)

(1) Ground the aircraft to prevent static electricity from causing fuel vapors to ignite (2) Defuel the aircraft (3) Rope off the aircraft maintenance area (4) Disconnect the battery (5) Pull the appropriate circuit breakers (6) Post tag-out signs (7) Pencil drain the fuel cell

Gearbox Assembly

(1) Houses the reduction gear train (2) Provides mounting pads for all or some of the accessories such as: Fuel pump and Accelerator Oil Pump Assembly Hydraulic Starter Speed Sensor

Compressor Section

(1) Is a centrifugal compressor (2) Supplies air for combustion and bleed air requirements

Tachometer generator

(1) Mounted and splined to the accessory gearbox (2) Creates an electrical reference signal that represents the rotational speed of the engine compressor (3) The reference signal is transmitted to the tachometer (RPM) indicator and is read as percent of compressor RPM

Oil Pressure Transmitter

(1) Mounted on the engine (2) Sends a proportional electrical signal to the flight station / cockpit

Fuel Flow Transmitter

(1) Mounted on the engine (2) The transmitter provides an electrical signal that is directly proportional to the mass rate of fuel flow and transmits the signal to the flight station / cockpit

Steps For Fuel Cell Entry (During)

(1) Notify maintenance Control (2) Don Personal Protective Equipment (PPE) (3) Open and depuddle the fuel cell (4) Aerate the fuel cell (5) Obtain and post the confined space entry certificate (6) Ensure a qualified safety observer is present at the fuel cell entry point (7) Ensure a fire guard is in position (8) Don the air-supplied respirator (9) Perform maintenance

Maintenance O Level

(1) Periodic inspection (2) Removal and replacement of components (3) Complete removal and replacement of the APU

Operation / Maintenance (APU)

(1) Power is developed through compression ambient air by a centrifugal compressor (2) Compressed air is mixed with fuel that is ignited to drive the turbine (3) Rotating shaft power of the turbine wheel drives the compressor, accessories, and main output drive pad

APU Safety Control System

(1) Provides automatic starting of the APU. Includes safety features to shut down the unit automatically or manually

APU Lubricating System

(1) Provides both pressurized and splash lubrication for all gears, shafts, and bearings within the engine

Combustion Section

(1) Provides mounting pads for the six fuel nozzles, one ignitor plug, and a combustion drain valve (2) Combustion chamber is of the annular type

Electronic Sequence Unit

(1) Provides the APU with programmed events such as starting, operational checks, and overspeed protection

Fire Warning Light

(1) Receives its signal from the fire detection element to illuminate the flight station / cockpit (2) When the temperature in the engine cavity reaches an overheat condition, the sensors will provide a signal, allowing a small current to flow, which is transmitted to illuminate the fire warning light

Turbine Section

(1) Single-stage, turbine is of the radial flow design (2) The compressor / turbine section is joined on a common shaft to make a single balanced rotating assembly and is supported by two main bearings

APU Starting System

(1) Starting is accomplished hydraulically using aircraft-mounted hydraulic accumulator (2) The nitrogen charged accumulator provides hydraulic pressure required by the hydraulic starter (3) The hydraulic charge releases upon actuation of the APU control switch in the flight station / cockpit

Dry Sump

(1) Stores oil in a separate oil tank external of the engine (2) Allows for larger supply of oil (3) Used primarily on the axial-flow engines

Wet Sump

(1) Stores oil within the gearbox and does not have an external tank (2) Used primarily on the centrifugal-flow engines

Fuel Cells / Tanks

(1) Stores the Fuel (2) Location depends on the number of tanks/cells in the fuel system and the type of aircraft. The cells are located within the fuselage and wings

Main Engine Bearings

(1) Support the compressor and turbine rotors and allow them to rotate freely (2) Normally between 3 and 7 main bearings are required

Multimeter

A measuring instrument for current, voltage, and resistance

Dynamic Electricity

A practical form of current flow that is used in everyday life. This form of electricity is easily produced, measured, and controlled

Auxiliary Power Unit Description

A small gas turbine engine located within the airframe of the aircraft

Types of Electricity

AC and DC

APU Subsystems

APU Starting System, APU Fuel System, APU Lubrication System, APU Ignition System, Electronic Sequence Unit, APU Safety Control System

Accessory Bearing Location

Accessories and Gearboxes

Types of Heat Exchangers

Air and Fuel

Portable Purging Equipment

Air blower used to evacuate the vapors from the fuel cell

Breathing Air System

Air-supplied respirator used to supple clean, compressed air

Power Up

All segments appear while the instrument performs a self-test. At the end of the test, meter will chirp once indicating that it is ready for use

In-Flight Refueling System

Allow an aircraft to receive fuel during flight Connected directly into the Pressure Fueling System of the receiving aircraft and permits the fuselage cells, wing tanks, and external tanks to be filled to capacity Accomplished by transferring fuel from a tanker aircraft, or a ship, through a refueling nozzle connected to the in flight refueling probe or servicing manifold of the receiving aircraft

Check Valve

Allows flow in one direction only

Bypass Valve

Allows fluid an alternate path of flow to maintain lubrication if filter becomes clogged

Check Valves

Allows fuel to flow in one direction only

Selector Valve

Allows the pilot to control the flow for selected purposes

Low Battery Indicator

Appears when approximately 100 hours of life remain. If left on, the meter will go to standby mode after one hour to save the battery

Oil Level Transmitter

Can be a Dip Stick or Sight Gauge or even an actual transmitter that send electrical signal to an oil level indicator in the cockpit

Screen Filter and Screen-disk Filter

Can be cleaned and reused

Synthetic

Capable of withstanding the higher operating temperatures and high bearing speeds of the gas turbine engine

Types of Filters

Cartridge, Screen, and Screen Disk

Coarse Mesh Screens

Collects contaminants

Power Section Assembly

Compressor, Combustion, and Turbine

Thermocouple Assembly

Constructed of two dissimilar metals, Alumel and Chromel, which, when heated, will create a small voltage that is directly proportional to the engine exhaust temperature Ex: Using heat excites the energy from the metals and creates that small voltage that sends it to the Indicator

Vent

Controls air pressure in the tank to ensure a constant supply of oil to the main oil pump

Lubrication System Pump's Purpose

Create a flow to a volume of fluid

Alternating Current (AC)

Current flow that reverses direction at specific intervals, defined as Hertz / Cycles. It is produced mechanically by an AC generator Ex: A TV Screen

Direct Current (DC)

Current that is a steady flow in one direction only. It is produced mechanically by a DC generator, or chemically by a battery Ex: A Flashlight

Types of bearings

Ball and Roller