Technical Training Manual for Boeing 737-600/-700/-800/-900 Engine Systems

BOSTONAIR Technical Training

BOSTONAIR TECHNICAL TRAINING LIMITED UK.147.0085 TECHNICAL TRAINING MANUAL BOEING 737-600/-700/-800/-900

Table of Contents

1 Engine air - introduction - 5 - 1.1 Purpose - 5- 1.2 Turbine Clearance Control - 5 - 1.3 Compressor Airflow Control 5- 1.4 Customer bleed - 5 - 1.5 General description - 7 - 1.5.1 General - 7 - 1.5.2 Turbine Clearance Control - 7 - 1.5.3 Compressor Airflow Control - 7 - 2 Functional description 10 - 2.1 High Pressure Turbine Active Clearance Control (HPTACC) - 10 - 2.2 Low Pressure Turbine Active Clearance Control (LPTACC) 10 - 2.3 Variable Stator Vanes (VSVs) - 10 - 2.4 Variable Bleed Valve (VBV). 10 - 2.5 Transient Bleed Valve (TBV) 10 - 3 Turbine clearance control 12 - 3.1 Introduction - 12 - 3.1.1 Purpose 12 - 3.2 High pressure turbine active clearance control 13 - 3.2.1 General Description 13 - 3.2.2 HPTACC component location - 15 - 3.2.3 HPTACC valve - 17 - 3.2.4 Functional description 19 3.3 Low pressure turbine active clearance control - 24 - 3.3.1 General description 24 - 3.3.2 LPTACC valve 25 - 3.3.3 Functional description 27 - 4 Variable stator vane system. 30 - 4.1 Introduction. - 30 - 4.1.1 Purpose 4.1.2 Component locations . 31 - 4.2 VSV Actuator 32 - 4.2.1 Physical Description. - 32 - 4.3 Functional description 34 - 4.3.1 General 34 - 4.3.2 Control. - 34 - 4.3.3 Operation - 34 - 5 Variable bleed valve system - 36 - 5.1 Introduction. - 36 - 5.1.1 General Description - 36 - 5.1.2 Component locations 38- - 1 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

Variable Bleed Valve System

5.2 VBV Actuator. 39 5.2.1 Physical Description - 39 - 5.3 VBV system doors - 41 - 5.3.1 General Description 41 - 5.3.2 Physical Description 41 - 5.4 Functional description - 43 - 5.4.1 General - 43 - 5.4.2 Control 43 - 5.4.3 Operation 43 - 6 Transient bleed valve 46 - 6.1 Introduction 46 - 6.1.1 General Description - 46 - 6.1.2 Component Locations 47 - 6.2 Transient bleed valve 49 - 6.2.1 Physical Description 49 - 6.3 Functional description 51 6.3.1 General 51 - 6.3.2 Operation 51 - 2 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

List of Figures

Figure 1: Bleed air take-offs .5 - Figure 2: Engine air - CFM56-7B Airflow - 6 - Figure 3: General description. - 8 - Figure 4: Engine air - general overview 9- Figure 5: Functional description 11 - Figure 6: Turbine clearance control 12 - Figure 7: HPTACC - general description 14 - Figure 8: HPTACC Component location 16 - Figure 9: HPTACC valve 18 - Figure 10: HPTACC valve - general. 19 - Figure 11: HPTACC Functional description 20 Figure 12: HPTACC - functional diagram 22 - Figure 13: HPTACC valve operation 23 - Figure 14: LPTACC - introduction 24 Figure 15: LPT ACC valve 26 - Figure 16: LPTACC valve schedule 27 - Figure 17: LPTACC Functional description 28 Figure 18: LPTACC Functional schematic 29 - Figure 19: VSV system - introduction 30 - Figure 20: VSV Component locations 31 - Figure 21: VSV Actuator 32 - Figure 22: VSV Actuator 33 - Figure 23: VSV - functional description 35 - Figure 24: VBV System - introduction 36 - Figure 25: VBV system - introduction (2) 37 - Figure 26: VBV - component locations 38 - Figure 27: VBV Actuator 39 - Figure 28: VBV Actuator - 40 - Figure 29: VBV System - doors. 42 - Figure 30: VBV Schedule 43 - Figure 31: VBV - functional description - 44 - Figure 32: VBV functional description (2) 45 - Figure 33: Transient bleed valve - introduction 46 - Figure 34: TBV - component location. 48 - Figure 35: TBV - description. 50 - Figure 36: TBV - functional description 52 - Figure 37: TBV - functional description (2) 53 - - 3 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

Abbreviations and Acronyms

DEU Display Electronic Unit EEC Electronic Engine Control EGT Exhaust Gas Temperature HMU Hydromechanical Unit HPC High Pressure Compressor HPT High Pressure Turbine HPTACC High Pressure Turbine Active Clearance Control LPC Low Pressure Compressor LPT Low Pressure Turbine LPTACC Low Pressure Turbine Active Clearance Control LVDT Linear Variable Differential Transducer RVDT Rotary Variable Differential Transducer TAT Total Air Temperature TBV Transient Bleed Valve TRA Thrust Lever Resolver Angle VBV Variable Bleed Valve VSV Variable Stator Vanes - 4 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

Engine Air System Introduction

Purpose of Engine Air System

1 Engine air - introduction 1.1 Purpose The engine air system has these control functions:

• Turbine clearance
• Compressor airflow.

Turbine Clearance Control Overview

1.2 Turbine Clearance Control The engine air system adjusts the clearances between the high pressure turbine (HPT) blades and shroud and the low pressure turbine (LPT) blades and shroud. Usually, the engine air system decreases the clearance between the rotors and the turbine case. This helps the engine use less fuel. The engine air system also increases the clearance between the high pressure turbine blades and shroud during some power conditions. This makes sure the HPT blades tips do not rub against the case.

Compressor Airflow Control Overview

1.3 Compressor Airflow Control The engine air system adjusts the low pressure compressor (LPC) and the high pressure compressor (HPC) air flows for all power conditions. These adjustments prevent an engine stall.

Customer Bleed Air

1.4 Customer bleed Engine bleed air from the 5th and 9th stage are used to supply the aircraft pneumatic system. This is discussed in Chapter ATA 36. NOTE: 5th and 9th stage are also customer bleed air offtakes! 5th. STAGE BLEED AIR 9th. STAGE BLEED AIR 4th. STAGE BLEED AIR

Figure 1: Bleed air take-offs - 5 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

CFM56-7B Airflow Diagram

ECUHMU FADEC START & TRANSIENT VALVE LPTACC VALVE FAN AIR (from scoop) cfm HPTACC VALVE Air ECHI (cooling) 1 LPT cooling 4th stage air 4th stage air Fan Air (t LPTACC valve) 9th stage air 9th stage air Nacelle cooling 5 6 · CUSTOMER BLEED (5th stage air) CDP CUSTOMER BLEED (9th stage air) THRUST REVERSER DEPLOYED AERO-THERMODYNAMIC STATIONS 2 12 13 23 24 25 15 27 3 4 41 42 48 49 495 18 5 55 8

Figure 2: Engine air - CFM56-7B Airflow - 6 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024 THE POWER OF FLIGHT

General Description of Engine Air System

Electronic Engine Control (EEC) Functions

1.5 General description 1.5.1 General The electronic engine control (EEC) receives airplane system data from the display electronic units (DEUs). The EEC uses this data to control the engine air system. The EEC changes the bleed airflows to change the turbine blade tips clearances. The EEC also controls compressor airflows to prevent stall. The EEC operates the air valves and the actuators through the hydromechanical unit (HMU). HMU servo fuel pressure moves the valves and the actuators. The engine air system has these subsystems:

• Turbine clearance control
• Compressor airflow control.

Turbine Clearance Control Subsystems

1.5.2 Turbine Clearance Control The engine air system controls turbine tip clearance when it controls the amount of cooling air that goes onto the turbine case. Turbine blade tip clearances decrease when the turbine case is cooled. These are the turbine clearance control sub-systems:

• High pressure turbine active clearance control (HPTACC)
• Low pressure turbine active clearance control (LPTACC)
• Transient bleed valve (TBV).

The HPTACC system sends HPC 4th-stage and 9th-stage air to the high pressure turbine (HPT) shroud support. The air flows through an HPTACC valve. The LPTACC system sends fan discharge air to the low pressure turbine (LPT) case. The air flows through the LPTACC valve. The TBV sends HPC 9th stage air to the low pressure turbine stage 1 nozzles for these two conditions: Engine start Engine acceleration. The TBV prevents HPC stall during start and acceleration.

Compressor Airflow Control Subsystems

1.5.3 Compressor Airflow Control These are the compressor airflow control subsystems:

• Variable stator vanes (VSVs)
• Variable bleed valve (VBV).

The VSV system controls the high pressure compressor (HPC) airflow. The VSV system makes sure the correct quantity of air flows through to the HPC which prevents HPC stall. The VSV system controls the HPC inlet guide vanes and the variable stator vanes of the HPC. The first three stages of the HPC have variable stator vane. The VBV system controls the low pressure compressor (LPC) discharge airflow. There are 12 variable bleed valves that let some LPC discharge air bypass the engine and mix with the fan discharge air. This airflow prevents LPC stall during fast deceleration. The VBVs also keep water out of the HPC and prevent foreign object damage (FOD) during low speed operation and during reverse thrust operation - 7 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

Engine Air System Overview

FAN AIR BOOSTER AIR 4th STAGE 5th STAGE 9th STAGE LPTACC VALVE IGN LEAD COOLING HP VALVE INTERNAL BLEED AIR LPT CLEARANCE CONTROL INTERNAL BLEED AIR INTERNAL BLEED AIR HPTCC VALVE NOSE COWL ANTI-ICE HPT CLEARANCE CONTROL NOSE COWL A/I VALVE BLEED VALVE TRANSIENT BLEED VALVE (TBV) OVERPRESSURE VALVE + START VALVE TO STARTER COOLER OVERBOARD TO PNEUMATIC MANIFOLD

Figure 3: General description - 8 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024

Engine Air System Components

DEU(S) 6666 6666 EEC HPTACC VALVE VBV ACTUATOR (2) HMU LPTACC VALVE TRANSIENT BLEED VALVE VSV ACTUATOR (2)

Figure 4: Engine air - general overview - 9 - Maintenance Course B1/B2 ATA 75 ENGINE AIR Issue 4 - October 2024