This document describes the components and operation of the FADEC (Full Authority Digital Engine Control) system used on the CH-47D Chinook helicopter. The FADEC system provides fully automated control of the engine to improve performance and safety compared to older hydromechanical fuel control systems. It controls engine starting, fuel flow, temperatures, speeds and more. The system has primary and reversionary control modes. The primary mode operates normally while the reversionary mode acts as a backup if the primary fails. Both modes automatically control engine operation during starting, flight, and shutdown. The FADEC system improves engine operation during transients and faults can be detected and recorded.

1. 1

2. U.S ARMY
CH-47D
CHINOOK
T55-GA-714A
(ECP D 218)
2

3. 3

4. SEGMENTED INCREASERD LIFE
MAGNOSTRICTIVE
1ST GP NOZZLE 1ST STAGE TURBINE
TORQUEMETER
TAILCONE
RUBBER (CONTAINMENT RING)
ABADABLE SEAL
IMPROVED GP
WATER SPACER
WASH
STAINLESS
STEEL 2ND GP NOZZLE
FADEC COMPRESSOR W/COOLED CYLINDER 4

5. FUEL SUPPLY
HY
PRIMARY
D
PR
HY
ES
DR Y
TN R
S
NA
R SIO
E VE
R
ACCESSORY
P3
5

6. 6

7. 7

8. UPPER
COMPRESSOR
HOUSING
SEVEN STAGE
AXIAL
COMPRESSOR
GP SHAFT
COMPRESSOR
ROTOR
No. 1
ASSEMBLY BEARING No. 2
BEARING
SINGLE STAGE
LOWER CENTRIFUGAL
COMPRESSOR COMPRESSOR
HOUSING
8

9. 9

10. 10

11. 11

12. 12

13. No
.4
TU
R BI
N E
13

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16. 16

17. 17

18. 18

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20. 20

21. NK
TA
TO
TO
RTN
RE
TO FWD COMP
AR
CO
P M
OI
LI
N
21

22. 22

23. CHI
PD
ETE
CTO
R
23

24. 24

25. PTIT
25

26. 26

27. 27

28. PR
ES
SU
RI
ZI
FLO NG
W DIV VA
IDE LV
R E
28

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30. 30

31. 31

32. 32

33. OV
ERS
PEED
VAL SOLE
VE NO
ID
33

34. 34

35. 35

36. A IR
L INE
A SH
W
ER
W AT
EF LUID
N
ASH LI
W
A TER
W
NOZZLES
FLUID AIR
36

37. 37

38. 38

39. 39

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45. 45

46. 46

47. FADEC
SYSTEM
INTRODUCTION
47

48. 48

49. HYDROMECHANICAL FUEL CONTROL
• Marginal Starting During Hot Restarts and
Cold Temperature Operations
• Slow Engine Acceleration Rates
• Compressor Stalls or Surges
• Mismatching of Engine Torque Under
Heavy Load Conditions
• Rotor Speed Droop During Transient Maneuvers
49

50. HYDROMECHANICAL FUEL CONTROL
• Lack of Safety Features or Mode Failure Protection
• Lack of Built-In Test or Self-Diagnostics
• Inability to Record Engine Faults, History,
and Limit Exceedence Values
• High Pilot and Maintenance Workload
• Require a Large Spares Inventory 50

51. FADEC ADVANTAGES
• Simplified Hands-Off Engine Starting
• Improved Engine Acceleration/Deceleration Control
• Power Assurance/Overspeed Test
• Independent Electronic Engine Overspeed Protection
• Engine Compressor Surge Detection And Avoidance
• Control System Self-Test, Self-Diagnosis
And Fault Identification 51

52. FADEC ADVANTAGES
• Engine History, Start/Component Cycle
And Limit Exceedence Recording
• Load Anticipation (Minimizing Rotor Droop)
• Accurate Torque Matching And Limiting Functions
• Automatic Switch-Over to an Independent
Back-Up Control System
• Engine Over-Temperature Avoidance
• No Field Level, System Adjustments
• On-Condition Maintenance
52

53. PRIMARY MODE FUNCTIONS
• Twin Engine Load
Sharing
• Electronic Power Turbine Speed
Governing
• Transient Load Anticipation Using Rotor Speed
And Thrust Rate
• Transient Torque Smoothing Using Power
Turbine Rates 53

54. PRIMARY MODE FUNCTIONS
• Contingency Power To Meet Aircraft
Demands
• Automatic Engine Starting, Sequencing
Ignition, Start Fuel, And Stabilized Engine
Operation At Idle
• Acceleration And Deceleration Using
Closed Loop NDOT* Control
• Engine Temperature And
Temperature Rate Limiting 54

55. PRIMARY MODE FUNCTIONS
• Compressor Bleed Valve Control (For
Both Transient And Steady State Surge
Margin)
• Surge Detection/Surge
Recovery
• Fuel Flow Limiting
• Engine Fail Detection
55

56. PRIMARY MODE FUNCTIONS
• Engine Power Assurance Test
• Engine History/Fault Recording
• Automatic Switch Over To The
Reversionary Channel In The Event Of
Primary Channel Hard Fault
• Data Bus For Decu To Decu Cross
Communication 56

57. REVERSIONARY MODE FUNCTIONS
• Automatic Start Sequencing Including
Over Temperature Protection
• Pilot Controlled Start Fuel Enrichment/De-Enrichment,
If Required Through ECL Modulation
• Proportional Power Turbine Governing And Automatic
Power Modulation Response To Thrust Rate Changes
• Engine 1 (2) Increase/Decrease Switch To Input Power
Turbine Changes For Accurate Load Matching Of The
Engines 57

58. REVERSIONARY MODE FUNCTIONS
• Full Contingency Power Capability
• Over Temperature Protection Throughout The Engine
Operational Range
• Engine Shutdown In Response To The ECL
• Tracking Of The Primary Channels Operation Allowing A
Smooth Switch- Over When The Reversionary Channel Is
Selected, Or The Primary Channel Fails 58

59. FADEC
SYSTEM
COMPONENTS
59

60. 60

61. 61

62. 62

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64. 64

65. 65

66. 66

67. 67

68. GEAR PUMP
SEAL DRAIN HMU DRIVE
SHAFT
FPU DRIVE PUMP OUTLET
JET
PUMP DISCHARGE
INLET PRESSURE TAP
INLET PRESSURE CONTROL BYPASS
TAP
CAVITY
BYPASS RELIEF
VALVE
BYPASS PRESSURE
REGULATOR
BYPASS HIGH PRESSURE
SCREEN RELIEF VALVE
68

69. REFER TO HMA COLOR HANDOUT
69

70. 70

71. 71

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74. 74

75. 75

76. E
LIN
P3
I NE
E NG
R
AI
T
EN
BI
AM
76

77. P3 FROM HMA
CU
DE
TO
GE
AU
P3
G CHECK VALVE
G HT
SI
77

78. 78

79. 79

80. 80

81. 81

82. T1
82

83. 83

84. 84

85. 85

86. 86

87. 87

88. 88

89. 89

90. FADEC SYSTEM
OPERATION
90

91. PRIMARY SYSTEM INTERFACE
ENGINE START SWITCH CONTROL ENGINE START AND
IGNITION RELAYS
NR SELECTOR (N2SET) SETS POWER TURBINE SPEED (N2)
PRI/REV SWITCH SELECTS OPERATION OF THE
PRI OR REV MODE
B/U POWER SWITCH REMOVES ELECTRICAL POWER
FROM THE PRIMARY CHANNEL
91

92. PRIMARY SYSTEM INTERFACE
LOAD SHARE SWITCH SELECTS PTIT OR TORQUE FOR
ENGINE LOAD SHARING
ENGINE OVERSPEED TEST ACTIVATES OVERSPEED TEST
SWITCH FUNCTION N2 < 81.3%)
ENGINE POWER ASSURANCE HEXADECIMAL DISPLAY ENG
TEST SWITCH TEMP MARGIN
92

93. PRIMARY SYSTEM INTERFACE
ENGINE CONDITION SCHEDULES CORE ENGINE SPEED (N1)
LEVER (ECL) AND CONTROLS FUEL SHUTOFF
THRUST CONTROL LOAD ANTICIPATION
POSITION TRANSDUCER
93

94. POSITION
NR SPEED
HEX DISPLAY
DECU/DECU DECU DECU/COCKPIT SIGNALS
POSITION
BEEP TRIM
HMU B/U PWR
SIGNALS IGNITION/START
RELAYS PRI/REV
NR SEL
P1 P3 DC PWR LOAD
ENGINE SIGNALS
PTIT
P3
PTIT
HMA TORQUE
OVERSPEED
SOLENOID FAILURE
INDICATION
START FUEL
SOLENOID
BLEED BAND T1
ACTUATOR P3
94

95. 95

96. PRIMARY SYSTEM OPERARIONS
ENGINE STARTING
ENGINE SHUTDOWN
POWER AVAILABLE
ACCELERATION AND DECELERATION
SURGE RECOVERY
STEADY STATE FLIGHT CONDITIONS
96

97. PRIMARY SYSTEM OPERARIONS
TRANSIENT FLIGHT CONDITIONS
TEMPERATURE LIMITING
TEMPERATURE LIMITING
POWER TURBINE OVERSPEED LIMITING
POWER ASSURANCE TEST
FAULT CODE RECORDING
ENGINE HISTORY RECORDING 97

98. 98

99. 99

100. REFER TO APPENDIX B1
100

101. 101

102. 102

103. PRIMARY SYSTEM
Ground Starting, Primary Mode (Normal
Operation, No Faults)
1. SET THE ECL TO GND
2. HOLD ENG START SWITCH UNTIL N1 = 10%
• PRIMARY CHANNEL WILL AUTOMATICALLY CONTROL
THE START SEQUENCING
1. STARTER
2. FUEL FLOW TO START FUEL NOZZLES
3. IGNITION
4. FUEL FLOW TO MAIN FUEL NOZZLES 103

104. PRIMARY SYSTEM
Ground Starting, Primary Mode (Normal
Operation, No Faults)
• TEMPERATURE LIMITING (AFTER LIGHTOFF PTIT 760°C)
REDUCES FUEL FLOW TO 100 PPH MINIMUM
• OVERTEMPERATURE DURING START (ABORT)
• FUEL SHUTOFF IF PTIT > 815.5ºC
• ENG FAIL INDICATION
• ECL TO STOP RESETTING THE START MODE
• AIR STARTS PROCEDURES ARE THE SAME
AS FOR A GROUND START 104

105. PRIMARY MODE
ENGINE SHUTDOWN
ECL MOVED TO GND TO ALLOW NORMAL
ENGINE COOL DOWN
ECL TO STOP
PRIMARY SYSTEM CLOSES THE METERING VALVE
TO THE 40 PPH POSITION
REVERSIONARY MODE WILL EFFECT COMPLETE
SHUTOFF OF FUEL WHEN THE ECL IS MOVED TO STOP
THE SHUTOFF FEATURE IS THE ONLY FUNCTION OF THE
REVERSIONARY MODE THAT IMPACTS
105
THE PRIMARY MODE.

106. PRIMARY SYSTEM
POWER AVAILABLE
GROUND IDLE
• ECL AT GND
• IDLE SPEED ADJUSTED FOR ENGINE INLET
TEMPERATURE
N1 = 50% - COLD DAY (-65°F)
55% - STD DAY (59°F)
59% - HOT DAY (135°F)
106

107. PRIMARY SYSTEM
POWER AVAILABLE
GROUND TO FLIGHT TRANSITION
• ECL MOVED TO FLT POSITION
FADEC WILL ACCELERATE ENGINE TO NP
GOVERNOR SET SPEED (ROTOR RPM SELECTED
BY THE NR SWITCH ON THE FADEC CONTROL PANEL)
ECL FLT POSITION SETS NG GOVERNOR
TO EMERGENCY POWER SPEED LIMIT 107

108. 108

109. REVERSIONARY CONTROL
TRANSFER TO REVERSIONARY
REVERSIONARY CHANNEL (REV 1(2) OFF)
WHEN IN PRIMARY, THE REVERSIONAR
CONTROL TRACKS N1
PILOT SELECTS REVERSIONARY OR
PRIMARY CHANNEL FAILURE
COCKPIT DISPLAY - FADEC 1 (2) ON
NORMAL TRANSITION TO REVERSIONARY WILL BE
SMOOTH, NORMALLY NOT REQUIRING PILOT ACTION
109

110. REVERSIONARY CONTROL
TRANSFER TO REVERSIONARY
IF THE REVERSIONARY CHANNEL IS HARD
FAULTED (REV 1 (2) ON)
PRIMARY SYSTEM FAILS TO FIXED
FUEL FLOW (FAILED FIXED)
IF PILOT SELECTS REVERSIONARY, SYSTEM CONTROL
FAILS FIXED TO REVERSIONARY SETTING
COCKPIT CONTROLS AND INDICATIONS
1. COCKPIT DISPLAY FADEC 1 (2) AND
REV 1( 2) INDICATION ON
2. THE EFFECTED ENGINE DOES NOT RESPOND
TO CONTROL CHANGES
110
3. INDICATED TORQUE SPLITS

111. 111

112. REVERSIONARY SYSTEM INTERFACE
CONTROL REVERSIONARY MODE
ENGINE START SWITCH CONTROL ENGINE START AND IGNITION RELAYS
ENGINE CONDITION LEVER (ECL) SCHEDULES CORE ENGINE SPEED (N1) AND
CONTROLS FUEL SHUTOFF
THRUST CONTROL POSITION LOAD SCHEDULING
TRANSDUCER
PRI/REV SWITCH SELECTS THE REV MODE
ENGINE OVERSPEED TEST SWITCH ACTIVATES OVERSPEED TEST FUNCTION N2 < 81.3)
ENGINE POWER ASSURANCE HEXADECIMAL DISPLAY ENG TEMP MARGIN
TEST SWITCH
INC/DEC SWITCH (BEEP) TRIMS CORE ENGINE SPEED (N1)
112

113. POSITION
NR SPEED
HEX DISPLAY
DECU/DECU DECU DECU/COCKPIT SIGNALS
POSITION
BEEP TRIM
HMU B/U PWR
SIGNALS IGNITION/START
RELAYS PRI/REV
NR SEL
P1 P3 DC PWR LOAD
ENGINE SIGNALS
PTIT
P3
PTIT
HMA TORQUE
OVERSPEED
SOLENOID FAILURE
INDICATION
START FUEL
SOLENOID
BLEED BAND T1
ACTUATOR P3
113

114. REVERSIONARY SYSTEM
ENGINE STARTING
ENGINE SHUTDOWN
CORE ENGINE SPEED GOVERNOR
PROPORTIONAL POWER TURBINE GOVERNOR
WF/P3DOT ACCELERATION AND DECELERATION
TEMPERATURE RATE OF CHANGE LIMITING
TEMPERATURE LIMITING
HYDROMECHANICAL BLEED BAND CONTROL
INC/DEC TRIM FUNCTION
FAULT CODE REPORTING 114

115. 115

116. 116

117. REFER TO APPENDIX B2
117

118. 118

119. REVERSIONARY
SERVO PISTON MECHANICAL
BLEED
STOP
ORIFICES METERING
REVERSIONARY LOADING PISTON
HOLE
Wf/P3 SERVO
MECHANISM
Wf/P3 LEVER CONTOUR SLEEVE
IN PRIMARY
IN REVERSIONARY 119

120. PISTON BLEED ORIFICE
POWER PISTON
FEEDBACK P3 PRESSURE
SPRING
P3 BELLOWS
MAX STOP
FLAPPER
VALVE
NOZZLE
EVACUATED BELLOWS
MIN STOP P3 LEVER
120

121. 121

122. REVERSIONARY MODE
GROUND STARTING
1. PILOT SETS ECL TO GND
2. HOLDS START SWITCH UNTIL N1 > 8%
AUTOMATIC CONTROL OF:
STARTER MOTOR (ABOVE 8%)
START FUEL SOLENOID
IGNITERS
START FLOW TO MAIN NOZZLES
Wf/P3 vs. N1 START SCHEDULE TO IDLE
ECL ENRICHMENT IF ENGINE TENDS TO STAGNATE
HAS NOT BEEN REQUIRED IN DEVELOPMENT ENGINE
TESTS
(-65º TO 135º F STARTS)
760º C TEMPERATURE LIMIT
FUEL CUTBACK TO 130 PPH MIN FLOW
AIR START
SAME PROCEDURE AS GROUND STARTS
WINDMILL SPEEDS WHERE N1 > 10% WILL START AS ECL IS MOVED FROM STOP
SHUTDOWN
ECL SET TO GND FOR ENGINE COOL DOWN ECL SET TO STOP 122
REVERSIONARY WILL IMMEDIATELY OPEN WINDMILL BYPASS FOR FUEL SHUTOFF

123. 123

124. 124

125. 125

126. 126

127. PAT
Power Assurance Test
Ref. Pg 8-9 0f the TM 55-1529-240-10
Perform First Flight of the Day
May be deferred to the Hover Check
a. NR Switch = 100%
b. ENG 1 ECL - Adjust
c. Thrust Control Lever - Raise until TRQ reads 60 to 80%. Stabilize for 30 seconds
d. Test switch ENG 2 - PWR ASSURANCE.
Check DECU display compare displayed value with PAT Trigger Value.
e. ENG 1 ECL - FLT
f. Repeat check with ENG 2 COND lever
g. THRUST CONT lever - Adjust
4. RRPM - Set as required
127

128. PAT
Power Assurance Test
Ref. Pg 2-55 0f the TM 55-1529-240-MTF
Perform First Flight of the Day
a. NR Switch = 100%
b. ENG 1 ECL - Adjust
c. Thrust Control Lever - Raise until TRQ reads 60 to 80%. Stabilize for 30 seconds
d. Test switch ENG 2 - PWR ASSURANCE.
Check DECU display (FE) An A means that the engine is operating at a
cooler temperature than a baseline spec engine. An F means that the
engine is operating at a warmer temperature than a baseline spec engine. .
Record Results.
d. THRUST CONT lever - Adjust
d. ENG 1 ECL - FLT
e. Repeat check with ENG 2 ENG COND lever
128

129. PAC
Power Assurance Check
Ref. Pg 2-76.1 0f the TM 55-1529-240-MTF
Ref. Section IV
Power Assurance Check Maximum Power Chart
Power Assurance Check Maximum Continuous Power Chart
Power Assurance Check engine Temperature Limits Chart
Power Assurance Check N1 Gas Generator Speed
Power Assurance Check Altitude Bands Chart
129

130. MONITORING FAULT CHECKS
Power-Up Prestart Checks
Pressure Sensors
Bleed Valve Solenoid
Primary Reversionary Change-Over Solenoid
Primary Switch-Over (Watchdog Timer) Circuitry
Programmable Read Only Memory (Prom)
Electronically Erasable Programmable Read Only Memory (Eeprom)
CONTINUOUS FAULT CHECKS
Airframe & Engine Interface Sensors
Electromechanical Components
Power Supplies
130

131. SOFT FAULT
• Failures Which Will Not Impair Normal Mode Control of the Engine or Aircraft
• Pilot Action Not Required
• No Cockpit Indications
• Fault Information Displayed in the Hexadecimal DECU Display.
HARD FAULT
• Failures Which Could Seriously Impair Operation of the Engine or Aircraft
• Primary Will Fail Automatically to Reversionary
• FADEC 1 (2) Will Be Displayed
REVERSIONARY HARD FAULT (REV 1 (2) ON)
• Automatic Switchover to the Failed Reversionary Will Not Occur and Due to the
Primary Mode Failure the Engine Is Failed Fixed.
• Fadec 1(2) and Rev 1 (2) Indications Will Be Displayed.
131

132. 132

133. FAULT STORAGE AND READOUT
133

134. REVERSIONARY FAULTS
134

135. 135

136. Tom Mietus
(610) 591-4148
thomas.r.mietus@boeing.com
Date: 10/18/99
Course:
PILOTS POWERPLANT COURSE (ECP D 218)
136

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