UNIVERSITI KUALA LUMPUR MALAYSIAN INSTITUTE OF AVIATION TECHNOLOGY

AIRCRAFT ELECTRICAL SYSTEM

ASSIGNMENT : ENGINE STARTING SYSTEM B777

Class :

4XBME2

Prepared By:

DURAIRAAJ A /L MARUTHAN 53259113186

MALIK REDZUAN BIN SULAIMAN 5325911

SITI SHAKIRA BAJUNID BINTI S.MOHAMED 53259113209

Prepared For:

SIR

ENGINE STARTING SYSTEM FOR BOEING 777

Introduction

The engine starting system uses pneumatic power to turn the N3 shaft to start the engine. You also use the system to motor the engine. The engine starting system operates on the ground and in the air. Flight deck switches and the EEC control the system.

The engine starting system uses these pneumatic power sources:

* Auxiliary power unit (APU)* Ground power unit (GPU)* Opposite operating engine.

General description of the system

The EEC controls the engine starting system using these inputs:

* Flight deck controls* Electrical power* Pneumatic power.

Start Selection

You can start the engines manually or automatically, but you normally do automatic starts. You control the type of start with the autostart switch.

The autostart switch sends a signal to the EEC on the systems ARINC 629 buses. When the autostart switch is in the ON position, the EEC controls fuel and ignition, and monitors the engine parameters. The fuel control switch (not shown) must be in the RUN position for the EEC to do an autostart.

When the autostart switch is in the OFF position, you manually control and monitor the engine start.

Engine Starting

When you put the start selector to the START position, it does these functions:

Energizes a relay in the ELMS Energizes a relay in the ELMS to supply 28v dc power through the EEC to energize the

starter control valve solenoid Sends analog and digital start signals to the EEC Sends a discrete signal to the air supply cabin pressure

controller (ASCPC).

See the engine control section for more information about the ERU (SECTION 73-21).

See the engine air supply section for more information about the ASCPC (SECTION 36-11).

The AIMS supplies a ground for a solenoid that holds the engine start selector in the START position. The EEC sends a digital signal to tell the AIMS when to release the selector. If the AIMS does not receive the signal from the EEC, it uses N3 to make a decision when to release the selector.

Starter Control Valve and Pneumatic Starter.

The EEC controls the starter control valve (SCV). When the valve is open, pneumatic power from the airplane air supply goes to the pneumatic starter. This causes the starter to turn the N3 rotor. The EEC uses valve position signals from switches on the valve for fault indications.

Component Locations

You open the left fan cowl to get access to these engine starting system components:

* Starter air duct* Starter control valve* Pneumatic starter* Starter quick attach/detach (QAD) adapter.

Engine Start Controls

The engine start selectors and the autostart switch are on the cargo fire/engine control panel on the P5 overhead panel.

Electrical operation of the system

You control the engine starting system with the autostart switch and the start selector. The EEC automatically controls the starter control valve (SCV).

Autostart Switch

The position of the autostart switch goes to the EEC digitally. When the switch is in the ON position, it arms the EEC to do an autostart operation.

Start Selector

When you put the start selector in the START position, it sends signals to these systems and components:* ELMS* ASCPC* EEC* AIMS.

ELMS Power

The ELMS supplies 28v dc power from the captain’s fligh instrument bus to energize the engine start control relay. This lets 28v dc power go through the EEC to energize the SCV solenoid.

ASCPC

The ASCPC uses the start signal to control the pressure regulating and shutoff valve (PRSOV) and the isolation valves in the pneumatic system. During an engine start, the ASCPC closes the related PRSOV and opens the applicable isolation valve(s). See the engine air supply section for more information about the ASCPC (SECTION 36-11).

EEC

The EEC gets an analog start signal directly from the start selector. It also gets a digital start signal from the OPAS through the EDIU. These signals tell the EEC that there is a command to open the SCV.

When you put the start selector in the START position, 28v dc power goes through the EEC to energize the SCV solenoid.

The SCV logic in the EEC removes the 28v dc power from the SCV solenoid at approximately 50 percent N3. This causes the SCV to close.

The SCV logic does not let 28v dc power energize the SCV solenoid if the N3 is more than the maximum starter engagement limit.

When the start selector moves to the NORM position, the engine start control relay de-energizes. This removes 28v dc power to the EEC.

Both channel A and channel B of the EEC get SCV position from switches on the valve.

AIMS

The AIMS controls the latching solenoid that keeps the start selector in the START position. The solenoid cannot move the selector. It only holds it in the momentary START position. The EEC sends a digital engine start signal to the AIMS. This signal is set true when the engine start begins. When the engine start signal is true, the AIMS latches the selector by energizing the solenoid.

The EEC sets the engine start signal false when any of theseconditions occur:

The EEC aborts an autostart The engine gets to low idle (approximately 63 percent N3)

When the engine start signal is false, the AIMS releases the selector by de-energizing the solenoid. The selector automatically moves to the NORM position when the solenoid de-energizes.

The AIMS also de-energizes the solenoid if you move the fuel control switch to CUTOFF when N3 is more than 50 percent.

If the digital engine start signal is not valid or is not available, the AIMS uses the analog N3 signal from the dedicated alternator to control the latching solenoid. For N3 less than 50 percent, the solenoid energizes. For N3 more than 50 percent, the solenoid de-energizes.

Warning/Indication On The System

Starter Control Valve and Pneumatic Starter

The EEC controls the starter control valve (SCV). When the valve is open, pneumatic power from the airplane air supply goes to the pneumatic starter. This causes the starter to turn the N3 rotor.The EEC uses valve position signals from switches on the valve for fault indications.

Engine Start Controls

The engine start selectors and the autostart switch are on the cargo fire/engine control panel on the P5 overhead panel.

ENGINE STARTING - STARTER CONTROL VALVE

Purpose: The starter control valve (SCV) opens to let air go to the pneumatic starter.

Physical Description: The SCV is a butterfly-type valve. It is electrically-controlled and pneumatically-operated.

Functional Description: A spring holds the SCV closed.The EEC sends 28v dc power to open the solenoid valve on the SCV. This lets air open the SCV. A filter cleans the air before it goes through the solenoid valve.The SCV position switches send valve position signals to the EEC. A visual position indicator on the valve shows the valve position.

Manual Override: You can manually open the SCV if it does not operate automatically. Use a 3/8 inch square drive to manually open the valve. You get access to the manual override through a hole in the left fan cowl.

Training Information Point: When you install the SCV, use the alignment marks on the valve body and air supply ducts to make the correct alignment.

ENGINE STARTING - PNEUMATIC STARTER SERVICING EFFECTIVITY

GeneralThe pneumatic starter oil system operates independently from the engine oil system. It has these parts:

Oil fill plug Oil level overflow plug Oil level sightglass Magnetic oil drain plug.

You open the left fan cowl to get access to the pneumatic starter.

Oil Fill Plug and Oil Level Overflow PlugYou remove the oil fill plug and the oil level overflow plug when you add oil to the starter. You gravity-fill the starter until oil goes out of the overflow port.

Oil Level SightglassThe oil level sightglass shows when oil servicing is necessary.It has three different ADD and FULL marks. You do not use the marks on the left side of the sightglass.

Magnetic Oil Drain PlugThe magnetic oil drain plug catches ferrous contamination in the starter oil system. The plug has threads that attach it to a drain plug housing in the bottom of the starter. The housing has a valve that keeps the oil in the starter when you remove the magnetic oil drain plug for inspection.

You remove the drain plug housing to drain the oil from the starter.

Training Information PointWhen you add oil to the starter, the correct oil level shows when oil goes out of the overflow port. Do not use the oil level sightglass to get the correct oil level.

ENGINE STARTING - FUNCTIONAL DESCRIPTION - START PROFILE

Normal AutostartWhen you enable an autostart, the EEC automatically starts the engine. You enable an autostart by doing these steps:* Push the autostart switch to ON* Turn the start selector to START* Move the fuel control switch to RUN.

The EEC opens the start control valve (SCV), which causes N3 to rotate.At 25 percent N3 or the maximum motoring speed (whichever is less) the EEC opens the high pressure shutoff valve in the FMU and energizes one igniter.When the engine speed gets to 50 percent N3, the EEC closes the SCV and de-energizes the igniter. At idle, the EEC sets the AIMS engine start signal to false. This causes the AIMS to de-energize the start selector latching solenoid. The selector returns to the NORM position.

Abnormal Autostart

If the EEC finds a problem during the first autostart try, it will do a second autostart try. Before it does another autostart try, it motors the engine to cool it and remove any fuel.

If an autostart problem occurs after the SCV closes, the EEC waits until the engine speed gets to the maximum starter reengagement speed before it re-opens the SCV.The EEC uses two igniters for the second autostart try.

Manual Start

When you do a manual start, the EEC only controls some of the start sequence. It does not monitor or control starting faults. You enable a manual start by doing these steps:* Push the autostart switch to OFF* Turn the start selector to START.

The EEC opens the SCV, which causes N3 to rotate. At 25 percent N3 or the maximum motoring speed (whichever is less) you put the fuel control switch in the RUN position. When the fuel control switch is in the RUN position and the N3 speed is correct, the EEC opens the high pressure shutoff valve in the FMU and energizes one igniter. When the engine speed reaches 50 percent N3, the EEC closes the SCV and de-energizes the igniter. At idle, the EEC sets the AIMS engine start signal to false. This causes the AIMS to de-energize the start selector latching solenoid. The selector goes back to the NORM position.

The engine starting system has these modes of operation: Autostart Manual start.

These are the flight deck controls you use for an engine start operation: Start selectors Autostart switch Fuel control switches.

It is important to monitor the engine parameters to find or prevent these fault conditions: Low starter air pressure No light-up Locked rotor(s) Hung start Hot start Starter shaft breakage Starter duty cycle exceedance.

Autostart OperationThis is a brief summary of the autostart operation procedure:

Put the autostart switch in ON Put the engine start selector in START Put the fuel control switch in RUN.

The EEC automatically controls and monitors the autostart operation. It will stop the operation if there is a fault condition. If the first autostart try fails, the EEC automatically does another start operation. But, EEC does not do a second autostart try for these fault conditions:

Locked rotor(s) Starter shaft breakage. On the ground, the EEC permits only two tries to start the engine. If the second try fails,

then the autostart operation stops.The start selector moves to the NORM position when one of these conditions occurs:

The engine starts (low idle) The EEC stops the autostart operation.

In the air, the autostart operation continues until the engine starts or you move the start selector to NORM.

Manual Start OperationThis is a brief summary of the manual start operation procedures:

Put the autostart switch in OFF Put the engine start selector in START Monitor the engine parameters for the correct indications

* Put the fuel control switch in RUN at 25 percent N3 or the maximum motoring speed.

You must monitor the manual start operation and stop the operation if there is a fault condition.

Starter Cutout

The EEC closes the starter control valve when the engine gets to 50 percent N3. The valve position is shown on the air synoptic display.

Training Information PointThe EEC does not use oil pressure as a input to find a starting fault.

ENGINE INDICATING – INTRODUCTION

PurposeThe engine indicating system supplies engine performance data to the AIMS to show on the primary display system. The indicating system has these subsystems:

Engine pressure ratio (EPR) Shaft speed Exhaust gas temperature (EGT) Turbine overheat detection Airborne vibration monitoring (AVM) Engine condition monitoring (ECM).

The ECM sensors supply data to the AIMS for the airplane condition monitoring system (ACMS). ACMS data is available through the MAT.

Component Locations

These engine indicating components are on the left side of the engine:* Accumulator* HP compressor exit thermocouple* EGT thermocouple assembly (6)* IP turbine overheat thermocouple (2)* P50 manifold tube.The remote charge converter (RCC) is in the strut. You must remove the left mid side fairing panel to get access to the RCC.The P20/T20 probe is in the inlet cowl at the 11:30 position.The dedicated alternator is on the front face of the external gearbox module at the 6:00 position. See the engine control section for more information about the dedicated alternator(SECTION 73-21).

Indications

The EICAS display and the secondary engine display showthese engine parameters:* EPR, engine pressure ratio* N1, LPC rotor speed* EGT, exhaust gas temperature* N2, IPC rotor speed* N3, HPC rotor speed* FF, fuel flow* OIL PRESS, oil pressure* OIL TEMP, oil temperature* OIL QTY, oil quantity* VIB, vibration.

INDICATIONS - PERFORMANCE AND ENGINE EXCEEDANCE MAINTENANCE PAGESPerformance Maintenance PageThe top part of the performance maintenance page shows general airplane and environment data. GROSS WT is the gross weight of the airplane. SAT is the static air temperature and TAT is the total air temperature. The temperatures show in degrees Celsius. GS is the ground speed and CAS is the calibrated air speed. The speeds show in knots. ALT is the altitude in thousands of feet. The bottom part of the performance maintenance page shows the same engine parameters as the EICAS display and the secondary engine display. These indications are described in their related sections. The page also shows the value for these indications:* P30* DUCT PRESS.P30 is the HPC exit pressure in psi. The EEC gets P30 from a tap on the HPC case.DUCT PRESS is the manifold duct pressure in psi. It comes from the air system cabin pressure controller (ASCPC).

Engine Exceedance Maintenance PageThe exceedance maintenance page shows exceedance profiles for rotor speeds and EGT. It can show up to eight different profiles. N1 and N3 can make four profiles, and N2 and EGT can make four profiles. The oldest profile is on the left.

The N1 and N3 profiles show the maximum actual rotor speed if it is higher than the redline. The profile also shows the redline value and the time the rotor speed is higher than the redline.The N2 profile shows if N2 is higher than the redline.

The EGT profile shows if the EGT is higher than the amber or redline. It also shows the type of exceedance as EGT START, EGT AMBER, or EGT REDLINE.The N2 and EGT profiles make a record of N2 or EGT in increments. The time next to each increment tells how long N2 or EGT was higher than that value. The total time of the exceedance shows next to the lowest increment. The highest N2 or EGT is at the top of the profile and does not have a time value.

Indications

The EPCS maintenance pages show engine parameters from many engine sensors. The parameters show for channels A and B of the EEC. There is a box around the channel that the EEC is using to control the engine.These engine parameters show on the EPCS maintenance page 1:

N1, LPC rotor speed (percent) N2, IPC rotor speed (percent) N3, HPC rotor speed (percent) TRA, thrust resolver angle (degrees) T/R, left and right thrust reverser position (percent deployed) PAMB, ambient pressure (psi) P30, HPC exit pressure (psi) P20, fan inlet pressure (psi) T20, fan inlet temperature (degrees C) VSV, variable stator vane angle (degrees) T24, IP intercompressor inlet total temperature (degrees C)(calculated value) OIL T, oil temperature (degrees C) OIL P, oil pressure (psi) FMV, fuel metering valve position (degrees).

These engine parameters show on the EPCS maintenance page 2: EGT, exhaust gas temperature (degrees C) EEC temperature (degrees C) P50, LPT exit pressure (psi).

Refer to the related ATA chapter for more information about these indications.

Status WordsThe status words at the bottom of the page show data about the EEC. Each word is a four-character hexadecimal number. When decoded, each word shows 16 different parameters.

Engine Parameter LimitsThe propulsion data limits maintenance page 1 shows data limits for these engine parameters:

Rotor speeds EGT Oil pressure Oil temperature.

Other Engine Data LimitsThe propulsion data limits maintenance page 2 shows these limits:

Exceedance profiles Takeoff thrust Minimum idle Oil quantity Vibration In-flight relight Cross-bleed start.

The exceedance profile display shows the limits for the EGT profiles. The EGT profiles show on the engine exceedance maintenance page (not shown). EGT OPER ORIGIN is the temperature at which the EGT exceedance profile starts when the engine is running. EGT START ORIGIN is the temperature at which the EGT exceedance profile starts during an engine start. DELTA is the temperature increment for the related exceedance profile.

TAKEOFF THRUST is the N1 value at which the AIMS sets the takeoff thrust discrete. The AIMS shows a takeoff warning if the takeoff thrust discrete is set and the airplane is not in the correct takeoff configuration.

The MINIMUM IDLE and DELAY display show data that the AIMS uses to find if the engine is running. MINIMUM IDLE is an N3 reference value. DELAY is a time delay in seconds. The AIMS usually gets an engine run discrete signal from the EEC. If that signal is invalid, it uses N3. If N3 is above minimum idle for more than the time delay shown, then AIMS sets the engine run discrete.

The OIL QTY: LOW display shows the low limit, in quarts, for engine oil quantity. When the quantity is less than the low limit, the oil quantity display on the secondary engine page (not shown) shows in reverse video (black letters on a white background). The letters LO also show next to the oil quantity display.

The VIB: WHITE display shows the vibration level that causes the vibration display on the secondary engine page (not shown) to show in reverse video (black letters on a white background). This vibration level also causes the vibration display on the secondary engine page to show automatically.

In-Flight Relight Data

The IN-FLIGHT RELIGHT display shows data points that the AIMS uses in the in-flight relight envelope (not shown). The inflight relight envelope shows on the EICAS display.Cross-Bleed Start Data

The CROSS-BLEED START display shows data points that define the cross-bleed start envelope. If the airplane is in the cross-bleed start envelope, the cross-bleed start annunciation (not shown) shows with the relight start envelope on the EICASdisplay.

APU Data LimitsThe APU display shows data limits for these APU parameters:

RPM EGT Oil pressure Oil temperature Oil quantity.

ENGINE INDICATING – SUMMARYThe engine indicating system supplies engine data to the EEC. The EEC monitors the engine parameters and sends them to the AIMS and the AVM signal conditioner unit. The AIMS shows the engine parameters on the EICAS display and the secondary engine display.These are the engine parameters that engine indicating system monitors:

EPR N1 (LPC rotor speed) N2 (IPC rotor speed) N3 (HPC rotor speed) EGT (T44) IP turbine temperature Engine vibration T25 (IPC exit temperature) P25 P160 T30 (HPC exit temperature).

EPR IndicatingEPR is the main indication for engine thrust. EPR is the ratio of LPT exhaust pressure (P50) to fan inlet pressure (P20). The EEC calculates EPR and sends it to the AIMS for display.

Shaft Speed IndicatingThe shaft speed indicating system monitors N1, N2, and N3. The N1 signals come from three LP speed probes. The N2 signals come from three internal IP speed probes. N1 and N2 signals go through the OPU to the EEC. The N3 signals come from the dedicated alternator. N3 signals to the EEC go through the PCU. N3 signals also go from the dedicated alternator to the AIMS and the AVM signal conditioner unit. The EEC sends digital N1, N2, and N3 signals to the AIMS. The EEC sends an analog N1 signal to the EDIU, AIMS, and the AVM signal conditioner unit. The EEC sends an analog N2 signal to the AVM signal conditioner unit.

EGT IndicatingMAS ALL PRE SB 777-RB211-72-B893The EEC uses eleven EGT thermocouple assemblies to measure the temperature at the LPT entrance.MAS ALL POST SB 777-RB211-72-B893The EEC uses seventeen EGT thermocouple assemblies to measure the temperature at the LPT entrance.MAS ALL

IP Turbine Overheat DetectionThe turbine overheat detection system has two thermocouples that monitor the temperature of the cooling air at the front and rear of the IP turbine. If the temperature is more than the overheat limit, the EEC sends a signal to the engine fire detection card. The engine fire detection card supplies engine fire warnings signals for flight deck indication. See the engine turbine overheat detection section for more information about turbine overheat detection (SECTION 26-12).

Airborne Vibration Monitoring (AVM)The AVM system measures engine vibration. The two engine accelerometers send electrical charges to the remote charge converter (RCC). The RCC changes the accelerometer electrical charges to voltage signals and sends them to the AVM signal conditioner unit. The signal conditioner unit uses the voltage signals and engine speed signals to calculate engine vibration. The AVM signal conditioner unit also contains engine balancing system (EBS) functions. It uses speed, vibration, and N1 onceper- revolution (OPR) signals to calculate a balance solution. You use the EBS to correct high engine vibration caused by the fan or the LPT. The signal conditioner sends the EBS data to the AIMS.

Engine Condition MonitoringThe engine condition monitoring system supplies this data to the EEC:

P160 (fan exit pressure) P25 (IPC exit pressure) T25 (IPC exit temperature) T30 (HPC exit temperature).

This data is sent to the ACMS function in the AIMS. You can get reports from the ACMS for engine condition monitoring.