ATA77 Engine Indicating Jet Aircraft Maintenance Fundamentals

Ameco Beijing Aviation College Training Manual Fundamentals Jet Aircraft Maintenance Fundamentals ATA 77 Engine Indicating JAR-66 Book No: JAMF ATA 77 ALL Lufthansa Technical Training GmbH Lufthansa Base Issue: July 2000 For Training Purposes Only ã Lufthansa 1995 For training purpose and internal use only Copyright by Lufthansa Technical Training GmbH All rights reserved No parts of this training manual may be sold or reproduced in any form without permission of: Lufthansa Technical Training GmbH Lufthansa Base Frankfurt D-60546 Frankfurt/Main Tel +49 69 / 696 41 78 Fax +49 69 / 696 63 84 Lufthansa Base Hamburg Weg beim Jäger 193 D-22335 Hamburg Tel +49 40 / 5070 24 13 Fax +49 40 / 5070 47 46 Ameco Beijing FUNDAMENTALS Aviation College ATA 77 ENGINE INDICATING For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING HAM US/F Li 24.8.98 Page Beijing Aviation College FUNDAMENTALS ATA 77 Lesson INTRODUCTION TO ENGINE INDICATIONS ENGINE INDICATION SYSTEMS Engine indications are used to monitor the parameters of the engine and its systems The engine indications can be divided into groups First, there are the performance indications that are also named primary indications Then there are the system indications that are also called secondary indications The third group of indications is used for engine trend monitoring and usually not shown in the cockpit The performance indications are used to monitor the performance and the limits of the engine and to set the thrust for the different flight phases The system indications are used to monitor the operation of engine systems such as the oil or fuel system They are also used to detect malfunctions quickly Engine trend monitoring is done on the ground to detect engine problems at an early stage It uses engine parameters that are automatically recorded by the aircraft condition monitoring system, (ACMS) For Training Purposes Only Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS HAM US Li 24.8.98 Page Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS Beijing Aviation College FUNDAMENTALS ATA 77 Lesson ENGINE PERFORMANCE INDICATION For Training Purposes Only ACMS ENGINE TREND MONITORING co nhung thong so khong dung de dieu khien ma chi dung de quan sat tuoi tho cua engine Figure Engine Indication System HAM US Li 24.8.98 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2008 For Evaluation Only ENGINE SYSTEM INDICATION Page Beijing Aviation College FUNDAMENTALS ATA 77 Lesson Engine Indication Systems (contd.) You can find engine indications such as the ones shown on this ECAM display system They have a combination of gauge type analog displays and digital readouts There are also analog indications with moving vertical bars such as the ones shown on this EICAS display For Training Purposes Only Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS HAM US Li 24.8.98 Page Beijing Aviation College FUNDAMENTALS ATA 77 Lesson For Training Purposes Only Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS Figure HAM US Li 24.8.98 Engine Performance Indication Page Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS Aviation College FUNDAMENTALS ATA 77 Lesson ENGINE PERFORMANCE INDICATIONS We use the secondary engine indications to monitor the correct operation of engine systems These are also called engine system indications The indications for the oil system monitor the oil quantity, the oil pressure and the oil temperature The engine vibration indication shows you any imbalance that occurs in the rotating parts of the engine For example an imbalance can be generated by damage to blades or bearings The nacelle temperature increases for example when there is a leakage of hot air in the engine nacelle The indications on the EICAS generally give the same information as the indications on the ECAM, although they are shown in a different way HAM US Li 24.8.98 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2008 For Evaluation Only The indication which is always located at the top is used to monitor and set the engine thrust Because it is not possible to measure the thrust directly, there are different indications which give an equivalent value This is either the rotational speed of the fan, called N1 or the engine pressure ratio The other performance indications are the engine rotor speed indications for each rotor system This means that in addition to N1, there is N2 and, if available, also N3 There is also the exhaust gas temperature indication (EGT) and the fuel flow indication Data for the indications is gathered by specific sensors or probes The data is usually electrically transmitted to the indicators Sensors fitted to engines with a FADEC system will first transmit the data to the FADEC system computer The computer then sends the data to the indicators or display system and also uses it to control the engine ENGINE SYSTEM INDICATIONS For Training Purposes Only Beijing Page Beijing Aviation College FUNDAMENTALS ATA 77 Lesson For Training Purposes Only Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS Figure HAM US Li 24.8.98 Engine Performance Indications Page Beijing Aviation College FUNDAMENTALS ATA 77 Lesson Engine System Indication (contd.) There are also warnings and cautions displayed on the ECAM / EICAS page when an indication exceeds a limit, or when, as shown here, the system detects a low oil pressure Or when a filter gets clogged as indicated here Or when an unlocked thrust reverser is detected For Training Purposes Only Lufthansa Technical Training Ameco ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS HAM US Li 24.8.98 Page Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON Vibration Indications (contd.) The vibration indication on modern aircraft is automatically controlled by the monitoring unit, therefore you will not find any manual switching In this example of an ECAM display there are indications for each engine One indication shows units of vibration for the N2 rotor system and one for the N1 rotor system The monitoring unit generates the indications from a single sensor signal This can be done by comparing the frequency of the vibration signal and the rotor speed signals Usually only the forward sensor is used for this indication, but the monitoring unit is able to switch to the aft sensor when the forward sensor fails For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING ENGINE VIBRATION MONITORING HAM US/F Li 24.8.98 Page 54 Lufthansa Technical Training Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON For Training Purposes Only ENGINE INDICATING ENGINE VIBRATION MONITORING Figure 27 HAM US/F Li 24.8.98 Vibration Indication on ECAM Page 55 Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON Vibration Indications (contd.) This example of an EICAS display shows the vibration in an analog and digital format There is only one value for each engine The monitoring unit usually selects the highest vibration signal for the indication The display also shows the sensor and filter functions that are used for the indication Four different modes of indication are possible in this example The first one shows FAN and means that the forward sensor is measuring the vibration of the N1 rotor LPT stands for Low Pressure Turbine and means that the aft sensor measures the vibration of the N1 rotor N2 means that the vibration of the N2 rotor system is measured by the aft sensor BB means broad band and shows the unfiltered vibration signal from the aft sensor This signal is used, for example, when a rotor speed signal is not available When a vibration reaches a certain critical level in some aircraft types the corresponding vibration indication starts pulsing Now the pilot must react to find the reason for the vibration for example by scanning other engine indications or even by power reductions or engine shut down For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING ENGINE VIBRATION MONITORING HAM US/F Li 24.8.98 Page 56 Lufthansa Technical Training Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON For Training Purposes Only ENGINE INDICATING ENGINE VIBRATION MONITORING Figure 28 HAM US/F Li 24.8.98 Vibration Indication on EICAS Page 57 Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON Vibration Indications (contd.) For some engines you can also use the vibration monitoring system for an ”On wing fan balancing” It helps to find the highest imbalance with its exact location on the rotor The location is given by the so called rotor phase angle This is the position on the rotor, measured in degrees, from a fixed reference point There is further information on this in lesson of unit 72 You can measure the reference point for example with a ”Trim Balance Sensor” This works like a rotor speed sensor but gives only pulse for each rotation You can find the phase angle indication for example on an EICAS maintenance page together with all vibration signals On other aircraft you will find it on the printout from the ACMS For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING ENGINE VIBRATION MONITORING HAM US/F Li 24.8.98 Page 58 Lufthansa Technical Training ENGINE INDICATING ENGINE VIBRATION MONITORING Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON N1 SPEED SENSOR For Training Purposes Only PHONIC WHEEL TRIM BALANCE SENSOR Figure 29 HAM US/F Li 24.8.98 Phase Angle Measurement Page 59 Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON FUEL FLOW INDICATION SYSTEM ARCHITECTURE The fuel flow indicating system provides different indications for the pilot: The actual fuel flow to the engines which is in kg or tons per hour and the fuel used since the engine was started This is in kg or tons The fuel flow indication allows you to monitor the performance and economic operation of the engines The engines usually have the same power setting and therefore each flow indicator should also show identical fuel flow The fuel used indication shows the mass of fuel which was burned since the last engine start on ground This allows to compare the performance of the different engines It also gives a redundant information for the actual fuel quantity You can calculate the actual fuel quantity by subtracting the amount of used fuel from the amount of fuel in the tanks at takeoff.The fuel used indication is usually automatically reset to 0, when the engine master switch is switched to on and the aircraft is on the ground To generate the fuel flow and fuel used indications there needs to be a fuel flow transmitter on each engine and then a calculation has to be done The calculation in modern systems is usually done by the FADEC system computer In the next segment we show you how the fuel flow transmitter works For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING FUEL FLOW INDICATION HAM US/F Li 24.8.98 Page 60 Lufthansa Technical Training Ameco ENGINE INDICATING FUEL FLOW INDICATION Beijing Aviation College FUNDAMENTALS ATA 77 LESSON For Training Purposes Only ACTUAL FQ = FQ AT TAKE OFF - FUEL USED FUEL FLOW SIGNAL FUEL FLOW FUEL USED Figure 30 HAM US/F Li 24.8.98 Fuel Flow Indication System Page 61 Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON FUEL FLOW TRANSMITTER The fuel flow transmitter measures the mass flow of fuel between the fuel control unit and the fuel nozzles There are different types of fuel flow transmitter, but their operation is always based on a basic law of Physics; force is equal to mass times acceleration All transmitter types measure the force which is applied by the mass of fuel In the transmitter type shown here the fuel mass turns a turbine against a spring and the deflection angle is measured To get the force you must accelerate the fuel This is done here by an impeller that rotates continuously driven by an electric motor The mass of fuel is proportional to the turbine angle because the acceleration of the fuel is constant A position transducer, such as synchro or LVDT measures the turbine angle and sent it to the indicator.The indicator shows the fuel flow directly and also calculates the fuel used value by an integration of the fuel flow rate For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING FUEL FLOW INDICATION HAM US/F Li 24.8.98 Page 62 Lufthansa Technical Training ENGINE INDICATING FUEL FLOW INDICATION Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON F= mxa DEFLECTION ANGLE POSITION SPRING TRANSDUCER IMPELLER MOTOR TURBINE For Training Purposes Only 3Æ AC MOTOR POWER Figure 31 HAM US/F Li 24.8.98 Powered Fuel Flow Transmitter Page 63 Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON Fuel Flow Transmitter (contd.) Modern fuel flow transmitters not need an electric motor with a power supply They use the fuel itself to generate the acceleration In this transmitter type the fuel flow turns a small turbine The rotating turbine also drivesa drum and an impeller which is located inside the drum Both are coupled by a spring The fuel drives the turbine, drum and impeller with a speed that is proportional to the volume of fuel Behind the turbine the fuel passes through a fixed straightener that stops all possible fuel spin The straightened fuel then passes through the rotating drum without affecting the rotation of the drum Then the fuel hits the impeller blades The force of the fuel delays the rotation of the impeller until this braking force is compensated by the force of the spring The angle between the rotating drum and the rotating impeller is proportional to the mass fuel flow The transmitter measures this angle with coils in combination with permanent magnets magnets are located on the drum and are located on the impeller When a magnet passes the coil, it induces a voltage pulse in the coil In our example this happens twice for each rotation With no fuel flow the angle is zero and therefore the magnets on the drum and the impeller pass the coils at the same time When there is fuel flow, the impeller magnet is delayed by an angle in proportion to the fuel mass When this happens the pulse from the impeller coil is also delayed The FADEC system computer now calculates the time between the pulses, which is proportional to the mass fuel flow An integration of the fuel flow value gives the required fuel used information For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING FUEL FLOW INDICATION HAM US/F Li 24.8.98 Page 64 Lufthansa Technical Training ENGINE INDICATING FUEL FLOW INDICATION Ameco Beijing FUNDAMENTALS Aviation College ATA 77 LESSON chi thi luong fuel tren dong ho: pound/h , kg/h, tan/h, DRUM STRAIGTHENER For Training Purposes Only TURBINE COILS Figure 32 HAM US/F Li 24.8.98 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2008 For Evaluation Only IMPELLER Fuel Flow Indication Page 65 Ameco Beijing Aviation College FUNDAMENTALS ATA 77 LESSON THIS PAGE INTENTIONALLY LEFT BLANK For Training Purposes Only Lufthansa Technical Training ENGINE INDICATING FUEL FLOW INDICATION HAM US/F Li 24.8.98 Page 66 Ameco TABLE OF CONTENTS Beijing Aviation College ATA 77 ENGINE INDICATING INTRODUCTION TO ENGINE INDICATIONS ENGINE INDICATION SYSTEMS ENGINE PERFORMANCE INDICATIONS ENGINE SYSTEM INDICATIONS ENGINE TREND MONITORING 2 6 10 ROTOR SPEED INDICATION INTRODUCTION TACHOMETER GENERATOR VARIABLE RELUCTANCE SPEED SENSOR INDICATIONS 12 12 14 20 24 EPR INDICATION INTRODUCTION PRESSURE SENSOR INDICATIONS 32 32 34 38 EGT INDICATION INTRODUCTION EGT PROBES INDICATIONS 40 40 42 44 ENGINE VIBRATION MONITORING INTRODUCTION VIBRATION SENSORS VIBRATION INDICATIONS 46 46 48 52 FUEL FLOW INDICATION SYSTEM ARCHITECTURE FUEL FLOW TRANSMITTER 60 60 62 Page i Ameco Beijing Aviation College TABLE OF FIGURES Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 32 Engine Indication System Engine Performance Indication Engine Performance Indications Engine System Indications Engine Trend Monitoring Introduction Tachometer Generator Direct Indication FADEC Generator Sensor and Phonic Wheel Variable Reluctance Speed Sensor Indications Exceedance Recording Exceedance Pointer N1 Command EPR Indication System Components Sensors and Transmitter Sensors and Computer EPR Indications EGT Indication System EGT Indication Components EGT Indications Vibration Monitoring Vibration Sensors Operation of Vibration Sensors Vibration Indication Vibration Indication on ECAM Vibration Indication on EICAS Phase Angle Measurement Fuel Flow Indication System Powered Fuel Flow Transmitter Fuel Flow Indication 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 Page: ii