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CFMI Proprietary Information. 1
CFMI Proprietary Information:
The information contained in this document is CFMI Proprietary Information and is disclosed in confidence.
It is the property of CFMI and shall not be used, disclosed to others or reproduced without the express
written consent of CFMI, including, but without limitation, it is not to be used in the creation, manufacture,
development, or derivation of any repairs, modifications, spare parts, designs, or configuration changes or
to obtain FAA or any other government or regulatory approval to do so. If consent is given for reproduction
in whole or in part, this notice and the notice set forth on each page of this document shall appear in any
such reproduction in whole or in part. The information contained in this document may also be controlled
by U.S. export control laws. Unauthorized export or re-export is prohibited.
For Training Purposes only!
Best practices, Hot Topics, Fleet issues, SB's
CFM56-7 AES Handouts
CFMI Proprietary Information. 2
Standard Day Sea Level CFM56-7B18 CFM56-7B20 CFM56-7B22 CFM56-7B24 CFM56-7B26 CFM56-7B27
Aircraft Application 737-600 737-600 737-600
Aircraft Application 737-700 737-700 737-700
Aircraft Application 737-800 737-800 737-800
Aircraft Application 737-900 737-900 737-900
Aircraft Application Navys C40A
Aircraft Application Boeing Business Jet
Aircraft Application COMBI
Engine Weight 5,205 pounds 5,205 pounds 5,205 pounds 5,205 pounds 5,205 pounds 5,205 pounds
T/O Engine Thrust lbs. 19500 lbs 20,600 22,700 24,200 26,300 27,300
T/O Engine Thrust daN 8,674 daN 9,163 daN 10,097 daN 10,765 daN 11,699 daN 12,144 daN
Thrust Option Model B1 B1 Optional B1 Optional B1 Optional
N1 RPM 100% 5,175 RPM 5,175 RPM 5,175 RPM 5,175 RPM 5,175 RPM 5,175 RPM
N2 RPM 100% 14,460 14,460 14,460 14,460 14,460 14,460
Max. N1 RPM 104% 5,380 RPM 5,380 RPM 5,380 RPM 5,380 RPM 5,380 RPM 5,380 RPM
Max. N2 RPM 105% 15,183 15,183 15,183 15,183 15,183 15,183
Ground Idle N2% 58.8% SDSL 58.8% SDSL 58.8% SDSL 58.8% SDSL 58.8% SDSL 58.8% SDSL
Ground Idle N1% 19.7% SDSL 19.7% SDSL 19.7% SDSL 19.7% SDSL 19.7% SDSL 19.7% SDSL
Maximum EGT Starting 725 degrees C 725 degrees C 725 degrees C 725 degrees C 725 degrees C 725 degrees C
Maximum EGT T/O 950 degrees C 950 degrees C 950 degrees C 950 degrees C 950 degrees C 950 degrees C
Appox. Normal EGT T/O 755 degrees C 744 degrees C 772 degrees C 773 degrees C 792 degrees C 811 degrees C
Max. Continuous EGT 925 degrees C 925 degrees C 925 degrees C 925 degrees C 925 degrees C 925 degrees C
Fuel flow lbs/per/hr 6,720 pph 7173 pph 8,008 pph 8,662 pph 9,616 pph 10,191 pph
SFC 0.345 0.348 0.353 0.357 0.366 0.373
Starting Fuel flow 500-600 pph 500-600 pph 500-600 pph 500-600 pph 500-600 pph 500-600 pph
5th stage bleed air temp. T/O 600 degrees F. 613 degrees F. 637 degrees F. 654 degrees F. 679 degrees F. 694 degrees F.
9th stage bleed air temp. T/O 888 degrees F. 906 degrees F. 936 degrees F. 959 degrees F. 991 degrees F. 1,010 degrees F.
5th stage bleed psig. T/O 120 psig 126 psig 137 psig 145 psig 157 psig 164 psig
9th stage bleed psig. T/O 275 psig 290 psig 314 psig 333 psig 360 psig 375 psig
CFMI Proprietary Information. 3
Standard Day Sea Level CFM56-7B18 CFM56-7B20 CFM56-7B22 CFM56-7B24 CFM56-7B26 CFM56-7B27
Oil Pressure Max. 362.5 psid 362.5 psid 362.5 psid 362.5 psid 362.5 psid 362.5 psid
Oil Pressure Cruise 50 psid 50 psid 50 psid 50 psid 50 psid 50 psid
Oil Pressure Min. 13 psid 13 psid 13 psid 13 psid 13 psid 13 psid
Oil Pressure Below Min. (10 seconds max. in a negative G operation only.)
Transient Oil Temp. 160 C (320 F) 160 C (320 F) 160 C (320 F) 160 C (320 F) 160 C (320 F) 160 C (320 F)
Max.Steady State Oil Temp. 155 C (311 F) 155 C (311 F) 155 C (311 F) 155 C (311 F) 155 C (311 F) 155 C (311 F)
Idle Steady State Oil Temp. 150 C (302 F) 150 C (302 F) 150 C (302 F) 150 C (302 F) 150 C (302 F) 150 C (302 F)
Steady State Oil Temp. 140 C (284 F) 140 C (284 F) 140 C (284 F) 140 C (284 F) 140 C (284 F) 140 C (284 F)
Amber Indication (284 F) (284 F) (284 F) (284 F) (284 F) (284 F)
Red Line Indication (311 F) (311 F) (311 F) (311 F) (311 F) (311 F)
Oil Tank Volume 5 US Gallons 5 US Gallons 5 US Gallons 5 US Gallons 5 US Gallons 5 US Gallons
.1 Gal/Hr. Normal All All All All All All
.2 Gal/Hr. Still OK All All All All All All
BBJ max. flight 16.32 hours .21 Gal/Hr.
737ERmax. flight 13.62hrs. .25 Gal/Hr.
ETOPS max. flight 12.13 hours N/A N/A N/A N/A .27 Gal./Hr
.3 Gal/Hr. Investigate Investigate Investigate Investigate Investigate Investigate
Max. Oil Consumption .4 Gal./Hr .4 Gal./Hr .4 Gal./Hr .4 Gal./Hr .4 Gal./Hr .4 Gal./Hr
Min. Usable Oil Volume 2.72 US Gallons 2.72 US Gallons 2.72 US Gallons 2.72 US Gallons 2.72 US Gallons 2.72 US Gallons
Min. Usable Oil Liters 2.72 10.3 Liters 2.72 10.3 Liters 2.72 10.3 Liters 2.72 10.3 Liters 2.72 10.3 Liters 2.72 10.3 Liters
Approved Oils Reference Service Bulletin 79-001Service Bulletin 79-001 Service Bulletin 79-001 Service Bulletin 79-001 Service Bulletin 79-001 Service Bulletin 79-001
CFMI Proprietary Information. 4
Engine STA CG 207.4 inches 207.4 inches 207.4 inches 207.4 inches 207.4 inches 207.4 inches
Engine CG WL 99.25 inches 99.25 inches 99.25 inches 99.25 inches 99.25 inches 99.25 inches
Engine CG BL 99.17 inches 99.17 inches 99.17 inches 99.17 inches 99.17 inches 99.17 inches
Engine Length 98.72 inches 98.72 inches 98.72 inches 98.72 inches 98.72 inches 98.72 inches
Width 83.4 inches 83.4 inches 83.4 inches 83.4 inches 83.4 inches 83.4 inches
Height 72 inches 72 inches 72 inches 72 inches 72 inches 72 inches
Starting N2 Speed (25% N2 or max motoring)
Starting Min. N2 Speed (20% N2) (20% N2) (20% N2) (20% N2) (20% N2) (20% N2)
Starter Limits 2 Minutes 2 Minutes 2 Minutes 2 Minutes 2 Minutes 2 Minutes
Starter engagement Flight 11% N2 Flight 11% N2 Flight 11% N2 Flight 11% N2 Flight 11% N2 Flight 11% N2
Starter Reengagement 0< 55% N2 0< 55% N2 0< 55% N2 0< 55% N2 0< 55% N2 0< 55% N2
Standard Day Sea Level CFM56-7B18 CFM56-7B20 CFM56-7B22 CFM56-7B24 CFM56-7B26 CFM56-7B27
Engine warm-ups 2 Minutes 2 Minutes 2 Minutes 2 Minutes 2 Minutes 2 Minutes
Engine Cool Downs 3 Minutes 3 Minutes 3 Minutes 3 Minutes 3 Minutes 3 Minutes
Engine warm-ups 1st time 5 Minutes 5 Minutes 5 Minutes 5 Minutes 5 Minutes 5 Minutes
AGB air pressure at idle 5 psi over ambient (15-17 psia) All CFM56-7B Models CFM56-7B Models CFM56-7B Models CFM56-7B Models
AGB air pressure at T/O (27-28 psia) All CFM56-7B Models CFM56-7B Models CFM56-7B Models CFM56-7B Models
Wind Milling Limits On Ground Max. 6 hours Max. 6 hours Max. 6 hours Max. 6 hours Max. 6 hours Max. 6 hours
CFMI Proprietary Information. 5
Performance based on no bleed or power extractions SLSD from Boeing.
For Training purposes only!
CFMI Proprietary Information. 6
CFMI Proprietary Information. 7
CFMI Proprietary Information. 8
CFMI Proprietary Information. 9
CFMI Proprietary Information. 10
1. The ADIRU’s provide pressure total to the EEC switches and ALTN mode indication.
2. 3 PITOT tubes and heaters – provides mach number
3. 2 AOA sensors
4. 1 TAT sensor 2 types aspirated and non-aspirated
5. 4 ADM’s air data to digital is done 4 times per second
6. 5 static ports
FMC – used for:
1. 1. Navigation – way points, radio, VHF, etc
2. 2. Operation of thrust
3. 3. Auto throttle interfaces: DFCA, ATC, safe minimum airspeeds, moves thrust levers.
4. 4. Assists in efficient speeds and altitude by storing data of:
a. a. Wf
b. b. Thrust
c. c. N1 limits
d. d. Fuel Used
e. e. FMC couple to the digital flight control systems
f. f. EEC-DEU-ATC
Thrust Modes – EEC switches
1. 1. Normal
2. 2. Soft – No change in thrust light ALTN illuminates
3. 3. Hard – Happens what EEC switch is pushed or thrust lever is at idle position
CDS – common display system is 6 screens that display flight data and engine system data using analog or digital data.
RAM – random access memory or erasable memory
NVM – non-volatile memory not erasable.
CPU – Micro-processor that does calculations by using Ram.
PDL – portable data loader down loads data history from the EEC or up loads software
EEPROM – erasable programmable memory read only memory
1. 1. Storage of control adjustments
2. 2. Fault Data
3. 3. Learning memory – engine cycles, peak N1, N2, EGT, etc.
4. 4. Adjustment of control schedules
5. 5. Vendor data
6. 6. Hardware data
7. 7. Check sum – checks data storage areas to see if they are corrupted or not. Also the calculated amount of storage and the sum of
the stored. Improves the integrity of the data previously stored.
CFMI Proprietary Information. 11
On the DP0303 connector on the EEC pin FF identifies
Eng 1. It goes through pin 27 of the DP0324 connector
on the eng pylon. It loops back through pin 28 and
returns to common pin X on the EEC.
Eng 2 basically the same expect is comes out of EEC on
pin HH to pylon connector pin 13 and back to the EEC
ground.
The EEC; DP0404 connector pin CC identifies the -800
through pin 20 on the DP0460 connector on the eng
pylon. It returns to ground through pin 36 (on the pylon
connector) and pin FF on the EEC connector.
The EEC; DP0404 connector pin BB identifies -700
through pin 19 on the pylon DP0460 connector using the
same common loop.
The EEC; DP0404 connector pin HH identifies -600
through pin35 on the pylon DP0460 connector using the
same common loop. The electrical harness connector
DP0303 and DP0404.
The reference information comes from the systemschematics manual, 73-21-11
CFMI Proprietary Information. 12
CFMI Proprietary Information. 13
Voltage
. 06 Sine / Cosine 3.28
. 06 Sine
Cosine 3.28
A
B
C
Sine =
Cosine =
Tangent =
A
C
B
C
A Sine
B Cosine
TRA calculated ratio
Tangent
CFMI Proprietary Information. 14
1. Question: What is the regulator in input monitoring mean?
Answer: Ref. ICD Appendix B -21 table shows the 0-16 levels called FMV
regulator definition. It shows the power level schedules, N1 is maintained at all
costs.
2. Question: In the fail safe mode will TEO,PEO, EGT be displayed?
Answer: TEO,PEO, EGT in fail safe mode will not be displayed.
Ref .9-15, 9-21. 9-23 and 15-29 tables
Fail safe 2 mode data tells us the system has failed and is a place holder.
3. Question: NVM is completely erased when programming of the new software is
done. The disk floppy is decoded with the disk for the software that CFM
provides. Everything is erased from the memory and even if it is sent back to the
repair shop it is gone forever none retrievable.
4. Question: PS3, if it is disconnected will default to model engine runs normal.
PS3, if it iced up inside engine runs can flameout.
PS3, if it leaking the engine can flameout, goes to min. idle.
Regulators
CFMI Proprietary Information. 15
Autothrottle computer and EEC interfaces
Q. What are the parameters used by the autothrottle computer ?
A. The autothrottle computer receives data from the FMC.
Q. How is the thrust calculated ?
A. The FMC calculates thrust from ADIRU parameters, aircraft type and engine model (program
pins). Parameters are used from 1,2 or both ADIRU's. The FMC then transmits Nl target to
EEC through the CDS/DEU, data to autothrottle and sets the Nl Bug to be displayed.
Q. How does it manage with flex Take Off ? Does a reference table exist?
A. The flex T/O is calculated by the FMC using the assumed temperature method. The calculated
OAT greater than the corner point must be entered through the CDU T/O page. The FMC
calculates the N 1 for flex T/O and sets the N 1 bug accordingly. The OAT entered for FLEX is
displayed on CDU. The aircraft is also able to work in derated mode. The derate level is entered through the CDU
and can be accumulated with flex T/O. For example: on 737-600 aircraft, max rating is
22,000lbs.
If 7-B22 engine is installed it is possible to choose full rated thrust or to select derated level at
20,600 or 19500lbs thrust. Then enter an assumed temperature. The selected thrust level is used
to calculate the flex T/O value.
On this aircraft, there is not any detent on throttle lever. Only a line indicates the position of the
throttle for T/O. When derate and/or flex is set, the FMC displays the Nl bug which corresponds
to the thrust level for T/O on CDU in the Nl sector. In manual mode, the crew pushes the throttle
lever until the Nl indicator aligns with the Nl bug. In autothrottle, once autothrottle is armed
on the glareshield panel, it is possible to make it active by pressing one of the two push buttons
located under the throttle lever handle. Then the auto throttle moves the levers so that the Nl
indicator aligns with the N 1 bug. This way, T/O power is automatically set.
Q. How does the system deal with the hard alternate mode ?
A. The FMC is able to calculate the correct thrust using the ADIRU parameters. Unlike the EEC,
the FMC can use parameters from ju.\,t ONE ADIRU. It mean.\' that when the EEC has a missing
ADIRU parameter, it does not continue to u~.e parameters from the other ADIRU and switches
to Alternate mode. Then the FMC still continues to calculate with just one ADIRU, setting the
correct thrust.
CFMI Proprietary Information. 16
Engine water wash every 500 cycles
about 10 degrees of EGT recovery each time.
Benefits – SFC and TOW
EGTM
Time on wing
Engine water wash
CFMI Proprietary Information. 17
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CFMI Proprietary Information. 19
CFMI Proprietary Information. 20
DT std
CFMI Proprietary Information. 21
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PO
CFMI Proprietary Information. 23
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CFMI Proprietary Information. 25
T25 CH A - Valid
T25 CH B - Valid
T25 SENSOR
Average Selected
T25 CH A – Valid
T25 CH B – Valid
Delta Difference beyond limits > 5 degrees approx.
T25 CH A - Valid
T25 CH B - Invalid Model Invalid - CH A selected
T25 CH A - Valid
T25 CH B - Invalid Model valid - CH A or model selected
T25 CH A - Valid
T25 CH B - Valid Average Selected
Closest to model selected
CFMI Proprietary Information. 26
TEO - (Range – 30 C. to 170 C.) + 5 degrees
TEO CH A = 100 C
TEO CH B = 104 C Average Selected = 102 C selected
TEO CH A = 100 C
TEO CH B = 110 C Average Selected = 110 C selected F/S 1
TEO CH A = 176 C
TEO CH B = 180 C Average Selected = 170 C selected F/S 2
CFMI Proprietary Information. 27
Calculated Models
1. PS3
2. N1
3. N2
4. T3
5. T25
6. FMV
7. VSV
8. VBV
CFMI Proprietary Information. 28
Engine Static Balance and AVM Task Form
CFMI Proprietary Information. 29
CFM56-7B -- EEC Alternate Mode Light Versus Engine Control Light (01-12-7321-04)
CFMI has received event reports suggesting that there may be some confusion over the difference between the cockpit ENGINE CONTROL light and the EEC
Alternate Mode (EEC-ALTN) light. This article is intended to clarify the distinction between these two lights, both in terms of dispatch ramifications and the
conditions under which these lights can illuminate. It is hoped that a better understanding of these distinctions will improve the troubleshooting, and reporting, of
events related to the illumination of these lights.
The figure below describes the dispatch limitations of the ENGINE CONTROL light and the EEC-ALTN light. Both lights are located in the flight compartment on
the P5 Aft Overhead Panel.
When ENGINE CONTROL light 1 or 2 is illuminated, the airplane is in a no-dispatch configuration and there is no MMEL relief for this condition. The ENGINE
CONTROL light can be illuminated only when the airplane is on the ground.
When EEC-ALTN light 1 or 2 is illuminated, both EECs must be placed into the alternate mode. Refer to the page 2-73-11.0 of the 737 Dispatch Deviations
Procedures Guide (DDPG), dated June 1, 2001 for relief from the EEC-ALTN light. The EEC-ALTN light can be illuminated when the airplane is in flight or on
the ground.
CFMI Proprietary Information. 30
• The EEC provides a ground to the light (pin 16) .
If the wire between the light and the EEC is shorted to ground
the light can go on when correlated maintenance messages
do not show.
• N1% = 10 degrees of EGT for 1%
• EGT indication failure no display EEC uses 15 C.
• N1 indication failure N2 model used.
• PS3 leak flameout or goes to min. idle
• PS3 blockage stall then flameout
CFMI Proprietary Information. 31
CFMI Proprietary Information. 32
CFM56-7B LOW ALTITUDE VSV SCHEDULE (ALT<17.5K)
-10
-5
0
5
10
15
20
25
30
35
40
8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000 13500
N2K25 (RPM)
VSV (DEGREES)
LOWALTITUDETRANSIENT
T2 > = 0 DEG C
LOWALTITUDEBODIE
LOWALTITUDETRANSIENT
T2 < 0 DEG C
LOWALTITUDESTEADY STATE
DAC SAC
CFMI Proprietary Information. 33
CFM56-7B VSV SCHEDULES
-4
-3
-2
-1
0
1
14200 14300 14400 14500 14600 14700 14800 14900 15000 15100 15200 15300 15400
N2ACTSEL (RPM)
VSV (DEGREES)
VSV DEMAND = VSV(PART A) + VSV(PART B)
CFMI Proprietary Information. 34
CFM56-7B VBV SCHEDULE (SLS)
0
5
10
15
20
25
30
35
40
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500
N1K12 (RPM)
VBV (DEGREES)
CFMI Proprietary Information. 35
CFMI Proprietary Information. 36
CFM56-7B HPTACC System
HPTACC support HPTACC Air Inlet Ports, 19°& 199°ALF
(4th, 9th, low 9th or mixed 4th/9th air supplied by HPT valve)
• The T3 sensor is currently used in -7B HPTACC logic
(T3 sensor will remain, used in other areas of control logic)
• -7B DAC HPTACC logic will remain unchanged (DAC is more marginal on cold starting)
CFMI Proprietary Information. 37
Current HPTACC Logic
• CFM56-7B has an active HPT blade tip clearance control system
 Goal of HPTACC system is to minimize blade tip rub, minimize take-off EGT
and to provide a tight clearance at altitude cruise for optimum SFC.
 4th stage HPC air, 9th stage HPC air or mixed 4th/9th can be impinged on to
the HPT shroud support to control HPT blade tip clearance
 Current logic calculates a demand shroud support ring ratio (support TC
temperature divided by T3) as a function of N2, altitude and time. FADEC
converts the demand ring ratio into a demand shroud support temperature by
multiplying by T3. The demand HPT valve position is set by comparing the
calculated demand support temperature to the measured shroud support
temperature, T3 and a calculated 4th stage air temperature
 Current logic has a failsafe schedule which is used when either the support T3
sensor are declared invalid (outside -60°C to 855°C range)
 Failsafe logic calculates demand HPT valve position as a function of N2 and
time. Schedules mixed mode or 9th stage air to HPT shroud. Conservative
from a blade tip rub standpoint but leads to increased take-off EGT and fuel
burn.
CFMI Proprietary Information. 38
• Current ring ratio schedules are a function on N2 and HPRTEMP
 Ring ratio is the support TC temperature / T3
 HPRTEMP is the nondimensional thermal state of the HPT rotor. HPRTEMP is a
function of N2 and time. The N2 component is related to the thermal growth of the
HPT rotor. The time component is related to the thermal time constant of the HPT
disk
Current -7B SAC Ring Ratio Schedules
-0.5
0
0.5
1
1.5
2
2.5
8000 9000 10000 11000 12000 13000 14000 15000 16000
Core Speed (RPM)
HPTACC Ring Ratio
HPRTEMP = -1
Ground Below 23K ft
Altitude 23-33 K ft
Altitude 41 K ft
HPRTEMP = +1
Cold Rotor, HPRTEMP = -1
Hot Rotor, HPRTEMP = +1
Steady State Schedules
HPRTEMP = 0
CFMI Proprietary Information. 39
• Valve position is a function of N2, altitude and time
• No change to HPRTEMP calculation except initial value at ECU power up will be 0.4 (rub protection)
• Cold rotor schedule set to match current warm start transition from 4th stage air to mixed mode
during accels (calculated demand positions > 100% are set to 100% (full 4th))
• Hot rotor schedule set to low flow 9th valve position (8%) to protect against re-accel rubs.
Proposed -7B SAC HPT Valve Position Schedules
0
50
100
150
200
250
8000 9000 10000 11000 12000 13000 14000 15000 16000
Core Speed (RPM)
HPT Valve Position Demand (%)
HPRTEMP = -1
Steady State Ground
Steady State Altitude
HPRTEMP > .05
100% Stroke : Full 4th
38-99% Stroke : Mixed Mode
37% Stroke : Full 9th
8% Stroke : Low Flow 9th
Steady State Altitude
(23K ft & Above)
Steady State Ground
(18K ft & Below)
Cold Rotor, HPRTEMP = -1
Hot Rotor, HPRTEMP > 0.05
CFMI Proprietary Information. 40
HPT Valve Position Comparison for Typical Flight Profile
• Start to idle : Current logic schedules 9th stage air to improve stall margin
 Start mode will remain 9th stage with new logic
• Idle : Current HPTACC air mode is initially 4th on cold starts (transitions to 9th as HPT
rotor heats up), 9th on warm starts
 Logic at idle air mode will be 9th on all starts to protect against blade tip rub during
take-off
• Take-off : Current air mode is 4th to minimize EGT
 Transient schedule defined so that air mode w/o T/Cs will remain 4th
• Climb : Current air mode is initially 4th then mixed as HPT rotor heats up
 Cold rotor schedule set so transition from 4th will be the same as current warm
engine starts.
 Steady state schedule defined to give same average valve positions (clearances) as
current logic. Based on analysis of existing engine data,  on HPT blade tip
clearance will increase by 0.4 mils. Existing measured flight test climb clearance
probe data indicates this increased variation is too small to cause additional blade
tip rub.
• Cruise : Current air mode is 4th.
• Descent : Current air mode is low flow 9th to protect against re-accel rubs.
 Hot rotor schedule defined so that air mode will remain low flow 9th.
CFMI Proprietary Information. 41
CFMI Proprietary Information. 42
VBV Door Assembly
CFMI Proprietary Information. 43
VBV Door Assembly
CFMI Proprietary Information. 44
CONTROL LOOP EXAMPLE
EEC HMU Actuator
Channel A
Channel B
CCDL Torque
Motor
Pilot
Valve
EEC Active Channel A
- Channel A wiring harness and torque motor coil used to drive HMU
- HMU fuel pressures used to drive Actuator
- Both channels of feedback used to evaluate Actuator position
Electric
Hydraulic
Active
CFMI Proprietary Information. 45
CONTROL LOOP EXAMPLE
Control Loop Fault:: THE HMU [loop] CURRENT IS OUT OF RANGE
EEC HMU Actuator
Channel A
Channel B
CCDL Torque
Motor
Pilot
Valve
The EEC senses that the control current delivered to the HMU torque motor coil is different than the
current returned from the circuit (indicates open or short circuit).
The EEC recognizes that it cannot drive the actuator with this channel and may change to the
standby channel (if it has more capability).
This is an electrical fault and indicates that the problem is in the EEC or HMU or the Wiring.
(NOTE: CFM56 wiring is very reliable, with MTBUR over 2 MEFH)
Electric
Hydraulic
CFMI Proprietary Information. 46
CONTROL LOOP EXAMPLE
Control Loop Fault:: THE [loop] POSITION SIGNAL IS OUT OF RANGE
EEC HMU Actuator
Cannel A
Cannel B
CCDL Torque
Motor
Pilot
Valve
The EEC senses that the Feedback from one (or both) channels is not in the valid range. Typically
the system can be operated properly using feedback from the other channel.
There is no reason to change active channels since valid feedback is obtained from the other
channel through the CCDL.
This is an electrical fault and indicates that the problem is in the EEC, the Actuator or the Wiring.
Electric
Hydraulic
CFMI Proprietary Information. 47
CONTROL LOOP EXAMPLE
Control Loop Fault:: THE [loop] DEMAND AND POSITION SIGNALS DISAGREE
EEC HMU Actuator
Cannel A
Cannel B
CCDL Torque
Motor
Pilot
Valve
The EEC senses that the Actuator did not move when commanded. There is no “CONTROL CURRENT
OUT OF RANGE” fault and the feedback signal from the actuator is valid.
Since there is no “CONTROL CURRENT OUT OF RANGE” fault, the EEC does not consider this an
electrical problem and will not change channels. The only exception would be a short between the two wires
in the control current (maintaining the current in this loop, but bypassing the torque motor coil).
This is a mechanical fault and indicates that the problem is in the HMU, the Actuator or the fuel lines.
Electric
Hydraulic
CFMI Proprietary Information. 48
CFMI Proprietary Information. 49
VSV LVDT Example 1
CFMI Proprietary Information. 50
VSV LVDT Example 2
CFMI Proprietary Information. 51
VSV LVDT Example 3
CFMI Proprietary Information. 52
VSV LVDT Example 4
CFMI Proprietary Information. 53
SUBTASK 12-13-11-970-002
(1)
Find the minimum oil level necessary to dispatch the airplane with these recommendations:
(a)
Before each flight, the indicated engine oil level in the flight compartment with the engine not in
operation must be 60% full or 12.00 U.S. quarts (11.40 liters) or more.
1)
If the airplane has more than one flight between oil servicing, make sure there is enough oil in the tank so
the indicated level is always greater than 60% before each flight.
2)
There must be 7 quarts (6.65 liters) or more of oil remaining in the tank by the end of the scheduled flights
for possible takeoff and go-around (TOGA) operation.
(b)
Calculate the oil usage from the flight(s) duration and the specific engine oil consumption.
(c)
Normal consumption is less than 0.4 US quart/hour or 0.1 US gallon/hour (0.38 liters/hour).
The consumption shows a gradual increase or sudden step increase.
The consumption is more than 0.8 US quart/hour or 0.2 US gallon/hour (0.76 liters/hour).
Engine Oil Consumption Limitations
CFMI Proprietary Information. 54
 Background
 Previous engine oil consumption limitations were common for all 737 minor models.
» Commercial 737NG oil consumption limited to 0.25 gallons per hour.
» 737 Boeing Business Jets limited to 0.22 gallons per hour
» Limitation contained in AMM section 71-00-00
 The FAA has changed position on engine oil consumption limitations.
» Required limitation in Section 9 of the Maintenance Planning Document
during certification of new minor models.
> 737-900
> 737-800 w/ winglets
» The FAA has indicated they may initiate an AD to require coverage of all
models in the MPD.
MODEL 737- WINGLET INSTALLED FUEL ENDURANCE (HOURS) OIL CONSUMPTION GUIDELINE US GAL/HR (LITER/HR)
600 NO 12.09 0.29 (1.098)
CFMI Proprietary Information. 55
No 9 0.22
737-900 No 0 0.34
Yes 0 0.31
737-800 No 0 0.33
Yes 9 0.22
737-700BBJ
737-700, -700C No 0 0.30
737-600 No 0 0.29
Oil Endurance
(gal/hours)
Number of Auxiliary
Tanks
737 Minor Model Winglet Equipped
Airplane Maintenance Manual Revision.
» Revised minor-model specific oil consumption limitations will be published in AMM section 71-00-00
 Maintenance Planning Document Revision
» Revised MPD Section 9 text will allow use of minor-model specific limits for 737-900 model & 737-800
model with winglets.
CFMI Proprietary Information. 56
Debris
Monitoring
System
CFMI Proprietary Information. 57
Debris
Monitoring
System
CFMI Proprietary Information. 58
Debris
Monitoring
System
CFMI Proprietary Information. 59
CFMI Proprietary Information. 60
Oil Cover
Oil Supply
CFMI Proprietary Information. 61
Bleed Air Issues
CFMI Proprietary Information. 62
Questions from Airlines class, on the Boeing side, dealing with bleed air systems.
1. When the 220 psi over pressure switch is activated due to an over pressurization problem and the PSROV is
stuck in the open position, where does the air bleed to?
The multiple failure situation stated would be most unfortunate! However, should there be an overpressure
fault, and the PRSOV remain open (note duct pressure indication) after the BLEED TRIP OFF light illuminates,
the excess pressure would go straight to the pneumatic system. There are no pressure relief valves in the
pneumatic system except for the APU bleed valve and high stage valve pressure relief valve. Note: For the APU
bleed valve to relieve pressure on the pneumatic system, with the APU not running, would also require the
additional failure of the APU bleed check valve. The pneumatic system ducts are designed to contain an air
pressure of 250 psi. The remaining pressure relief is the relief valve for the high stage valve. This valve opens at
160 psi and its primary purpose is to protect the inner high stage valve mechanism. Due to the volume of air
present in the interstage duct, it is not designed to relieve all the excess pressure in the interstage duct.
2. How can we regulate engine pressure if this occurs at the Top Of Descent?
To answer the question, the only way for a pilot to regulate the engine bleed pressure should both the high stage
valve and the PRSOV fail open is to reduce power on the affected engine. Unregulated pressure of the 9th stage
of the HPC at idle, at sea level, is approximately 18 psi. Unregulated 9th stage pressure at takeoff power is
approximately 350 psi. Unregulated pressure of the 5th stage of the HPC at idle, at sea level, is approximately 7
psi. Unregulated 5th stage pressure at takeoff power is approximately 160 psi. For an ETOPS flight, if this
condition occurs before reaching equal distance point (EDP) the pilots would air turnback. If the condition
occurred after EDP, the pilots would have to continue on with one engine power reduced to near idle speed.
Boeing 737 Operations Manual, Checklist Introduction, Chapter C1, Non-Normal Checklists, Section 2: “Non-
Normal checklist Operation:…While every attempt is made to establish necessary non-normal checklists, it is
not possible to develop checklists for all conceivable situations, especially those involving multiple failures. In
certain unrelated multiple failure situations, the flight crew may have to combine elements of more than one
checklist and/or exercise judgment to determine the safest course of action. The captain must assess the
situation and use sound judgment to determine the safest course of action.”
CFMI Proprietary Information. 63
3. What components can cause an overpressure on the ground while on T/O roll?
Example: moving the throttle from idle to T/O power.
• A fast engine acceleration where a slower reacting high stage valve could cause high 9th stage
pressure to activate the over pressure switch before the high stage valve fully closes. Note: There is
always a slight lag between pressure changes at the 9th stage of the HPC, relative to N2 speed
changes, and reaction by the high stage valve. This lag can increase with an older, more warn out
valve.
• Mx inadvertently installs a 180-psi overpressure switch on the bleed air regulator instead of the
220-psi overpressure switch preferred for AQs –7B26 engines. Note: Using a 180 psi overpressure
switch on –7B26 and –7B27 engines can possibly cause nuisance bleed trip conditions.
• A failure (crack or break) of the high stage valve downstream sense line. Note: This line provides
interstage duct pressure reference to the high stage valve for pressure regulation.
• A failure to the full-open position of the high stage valve.
• Failure of the overpressure switch on the bleed air regulator.
• Failure of the K8 relay in the air conditioning accessory unit (ACAU).
4. When the lower display unit is showing the systems page (display of FLT CTRL Pos, Hyd Qty), when
an engine alert comes up (Lo oil Qty), will the message come up automatically on the displays or do
you have to return to the engine primary page to see the message alert?
If the lower DU is in MFD and is currently showing Systems, any abnormal secondary engine
indication alert will automatically activate the upper center display to show a compacted secondary
engine display. The alert will now be visible on the upper center DU while the lower center DU will
continue to show Systems information.
CFMI Proprietary Information. 64
Maintenance Tips on bleed trip problems and duct split problems.
• Check for proper function of the two duct pressure transmitters.
• Check for proper function of the duct pressure indicator.
• Check for proper function of the pre-cooler control valve sensor.
• Check for proper function of the 450F thermostat for the PRSOV.
• Check to ensure the sense line from the 450F thermostat to the PRSOV is intact, not leaking, no loose
connections.
• Check to ensure the PRSOV downstream sense line is intact, not leaking, no loose connections.
• Check for proper and smooth operation of the PRSOV.
• Check to ensure there are no internal leaks in the PRSOV.
• Check for proper operation of the 490F over-temp switch.
• Check for proper operation of the 180/220 psi. overpressure switch, whichever one is installed.
• Check to make sure the high stage valve closes completely.
• Check for proper operation of the pre-cooler control valve.
• Check the pre-cooler for obstructions, debris, clogging, damage.
• Check to ensure the seal between the pre-cooler control valve and pre-cooler is intact, not damaged,
and in the correct position.
• Check the inlet to the pre-cooler control valve, on the left side of the 12:00 fan support strut is not
obstructed by dirt or debris, is not damaged.
Note: The last four items are particularly important after the flight crew reports of bird ingestion by an engine.
CFMI Proprietary Information. 65
Couple of basics:
It could also be as simple as a gauge. To check this, open the Isolation Valve
and see if the needles match up. If they do, you have eliminated the gauge.
(Many people forget this step).
8-10 psi is the pressure that is generated by the engine at IDLE from the
5th stage, 18-22 psi from the 9th stage at IDLE. 40 psi is within the range
of pressures for the engine operating IN FLIGHT (42 +/- 8 psi) once PRSOV
has begun to modulate and regulate pressure. (For the entire operation of
the system, please call). All major valves in the engine pneumatics area
are pneumatically operated, which means they have reasonably wide tolerances
(i.e. 42 +/- 8 psi) and are relatively slow (compared to electrically
operated valves) to function.
The PRSOV (Pressure Regulating and Shutoff Valve) has three functions -
ON/OFF, Pressure Regulation, Temperature Regulation. The Precooler Control
Valve regulates the amount of cooling air to the Precooler to normally
regulate bleed air temperature. If the Precooler Control Valve fails to
provide the proper amount of cooling air or the the Precooler is
blocked or dirty, then the temperature would rise above the designed
390-440F/199-227C. Once the bleed air temperature rises above 450F/232C, the
450F thermostat will open to bleed control pressure to the PRSOV causing it
to modulate toward the closed position (thereby decreasing the amount of hot
air). At this point the PRSOV is favoring temperature rather than pressure.
So for the same throttle position, the pressures would be different. How
much different is dependent on the amount of blockage/failure. If the over
temperature condition continues to worsen and decreasing pressure (and air
flow) through the PRSOV does not decrease the temperature, the 490F/254C
switch comes into play and causes a Bleed Trip Off.
If this pressure split comes from a precooler being dirty, usually the onset
of this comes over a period of time. So if a crew runs up and engine and
the maximum pressure they can get is 38 psi, this is within limits but may
need to be monitored. If the Precooler continues to accumulate dirt, over
the next couple of days/weeks the pressure will continue to decrease when
the throttles are in the same original position. Since few spend a lot of
time looking up at the gauge on the P5 panels, this subtle decrease in
pressure is rarely noticed until the duct pressure split is sizable.
If this is a Precooler Control Valve stuck closed the onset should be quicker.
1. Ram Air light is on at 35k or greater heat
exchangers are dirty.
2. No bleed air at T/O but bleed trips too much
pressure the high stage valve is stuck open.
3. Precooler dirty it doesn’t cool, good pressure,
then clean Precooler and monitor. Pressures
should be at idle:
9th 8-20 psi
5th 8-10 psi
4. Data Info.
400 F = 200 C
42 psi + 8 psi is normal
Engine 9th 340 psi
Engine 5th 160 psi
(Regulated lower)
5. APU check valve failure a dual air bleed light
indication. Result may be an APU failure.
6. Bleed trip Light off Temp. Problem
7. Bleed trip Light on pressure Problem
8. Bleed trip Light on after 5-6 SECONDS
9. Push Reset – TLA
10. Move TLA slowly to see plateau pressure of
the 9th about 80% N2 or N1 47%
Couple of basics hints:
CFMI Proprietary Information. 66
Questions from AES class follow-up.
Answers from PSE rewritten by Ted
Q1. Why is there a large difference between the actions of maintenance technicians and pilots in
regards to the starter remaining engaged due to the air start valve not closing?
Answer PSE – The pilots must consider in their situation if the starter remaining engaged, due to
the air start valve has not closed, are they in flight or on the ground. The technician is responding
on the ground only. A checklist must be followed by the pilot, which causes a longer time in most
cases to respond to this situation.
Q2. The EEC alternator failure occurred on one of our aircraft and the ALTN light came on
generating a fault code label of 172. How is this possible to have these two signals linked and
why did this happen?
Answer PSE – The EEC reset feature during start of the FADEC 3 during initialization started in
the soft ALTN mode. The EEC reset then would switch back to normal mode if everything
returned to a normal condition. This situation was corrected with a software change to the
FADEC 3.
Q3. Why is the EEC cooled in flight and not on the ground?
Answer PSE – The EEC is cooled on the ground by the ram air duct. The airplane is normally
turned into the wind for engine runs still allowing for cooling also. In flight we do not need the
extra cooling as on the ground. It has been working well so far, except one situation of an EEC
overheat caused by a CTAI valve clamp loose or possible crack in the valve that blew hot air onto
the EEC.
CFMI Proprietary Information. 67
ETOPS - Extended Range 180 minutes
CFMI Proprietary Information. 68
Extended-range twin-engine operations (ETOPS) have become common practice in
commercial aviation over the last 15 years. Maintenance and operational programs
for the twinjets used in these operations have received special emphasis, and
reliability improvements have been made in certain airplane systems. Many
operators are now considering the merits of the ETOPS maintenance program for
use with non-ETOPS airplanes.
In 1953, the United States developed regulations that prohibited two-engine
airplanes from routes more than 60 min (single-engine flying time) from an
adequate airport. These regulations were later formalized in U.S. Federal Aviation
Administration (FAA) Federal Aviation Regulation 121.161. The ETOPS program,
as outlined in FAA Advisory Circular (AC) 120-42A, allows operators to deviate from
this rule under certain conditions. By incorporating specific hardware improvements
and establishing specific maintenance and operational procedures, operators can
fly extended distances up to 180 min from the alternate airport. These hardware
improvements were designed into Boeing 737-600/-700/ -800/-900 and 777
airplanes.
ETOPS - Extended Range 180 minutes
CFMI Proprietary Information. 69
1. ENGINE HEALTH MONITORING
ETOPS maintenance procedures were created to ensure the safety and reliability of
flights operating at extended distances from alternate airports and to prevent or
reduce the probability of a diversion or turn back with one engine out. These
maintenance procedures are equally effective for any commercial airplane with any
number of engines. Most traditional maintenance programs are based on regularly
scheduled preventive maintenance and on the ability to predict or anticipate
maintenance problems by studying failure rates, removal rates, and other reliability
data. However, the ETOPS philosophy is a real-time approach to maintenance and
includes continual monitoring of conditions to identify problems before they threaten
airplane operation or safety.
ETOPS
CFMI Proprietary Information. 70
Two items in the ETOPS maintenance program that best illustrate this real-time
approach are oil consumption monitoring and engine condition monitoring.
Oil consumption monitoring.
A typical maintenance program requires checking engine oil before every flight (but only
once each day on the 737, as approved by the FAA) and the auxiliary power unit (APU)
oil less frequently (such as every 100 hr). The quantity of oil added and flight hours for
each leg should be noted in the maintenance logbook.
The oil consumption rate, the amount of oil used per hour of operation on the previous
flight leg, should be calculated for both engines and the APU during ETOPS before
dispatch. The resulting number provides a better indication of oil usage or loss than the
quantity of oil added. If the rate is acceptable, the flight can be released; if not, the cause
of the increased usage must be addressed before dispatching the airplane on an
ETOPS flight. This increase can frequently be caused by an oil leak, which is easy to
detect and repair.
The consumption rate data is also logged to track long-term variations in consumption
rates (fig. 1). This allows the operator to determine if problems are developing so they
can identify and implement solutions before serious engine or APU degradation occurs.
ETOPS
CFMI Proprietary Information. 71
Engine condition monitoring (ECM).
For many years, ECM computer programs have been available for all engines used on
Boeing airplanes. The engine manufacturer supplies ECMs to help operators assess the
general health of their engines. The programs allow for monitoring of such parameters
as N1, N2, exhaust gas temperature, fuel and oil pressures, and vibration (fig. 2). Most
operators use an ECM program regardless of whether they fly ETOPS routes. ETOPS
operators are required to use ECMs to monitor adverse trends in engine performance
and execute maintenance to avoid serious failures. These failures could cause in-flight
shutdowns, diversions, or turn backs. In some cases, oil consumption data and ECM
data can be correlated to define certain problems.
ETOPS
CFMI Proprietary Information. 72
2. PRE-DEPARTURE SERVICE CHECK
FAA AC 120-42A requires certain ETOPS systems to be checked before each flight.
Boeing determined that the transit check in the maintenance planning data document
was sufficient to meet the AC requirement. This is because certain systems relating to
ETOPS were redesigned for greater reliability and dispatch requirements were altered
for ETOPS (e.g., minimum equipment list requirements). However, because of the oil
consumption monitoring requirements for ETOPS, the APU check interval on the 737,
757, and 767 was changed to the transit check for ETOPS airplanes. The engine oil
servicing interval changed only on the 737. These two changes and the calculation of
consumption rate are the only changes necessary to the standard transit check to form
the ETOPS predeparture service check.
ETOPS
CFMI Proprietary Information. 73
3. BASIC AND MULTIPLE-SYSTEM MAINTENANCE PRACTICES
Two programs -- resolution of discrepancies and avoidance of multiple similar system
maintenance -- are outlined in AC 120-42A.
Resolution of discrepancies.
This program requires items that are repaired or replaced to be checked for proper
installation and operation before the work is signed off on the maintenance log. This
ensures that the item is actually fixed and that no new problems were introduced during
maintenance. This maintenance practice is applicable to all airplanes. Avoidance of
multiple similar systems maintenance.
Maintenance practices for the multiple similar systems requirement were designed to
eliminate the possibility of introducing problems into both systems of a dual installation
(e.g., engines and fuel systems) that could ultimately result in failure of both systems.
The basic philosophy is that two similar systems should not be maintained or repaired
during the same maintenance visit. Some operators may find this difficult to implement
because all maintenance must be done at their home base.
However, methods exist for avoiding the problems that may be introduced by working on
two similar systems simultaneously. For example, different personnel can perform the
required work on the similar systems, or they can ask each other to review the work
done on each system. If the systems are checked after performing maintenance
according to the resolution of discrepancies program, any problems introduced during
maintenance should be identified and corrected before releasing the airplane for flight.
CFMI Proprietary Information. 74
4. EVENT-ORIENTED RELIABILITY PROGRAM
An event-oriented reliability program associated with ETOPS differs from conventional
reliability programs, which rely on historical data or alert levels to determine when an
item should be investigated for possible corrective action.
In an event-oriented reliability program, each event on an ETOPS-significant system is
investigated to determine if a problem could be reduced or eliminated by changing the
maintenance program. Examples of events include a failure, removal, or pilot report.
Events can also be monitored to detect long-term trends or repeat items. Not all events
warrant such detailed investigations; continual monitoring and awareness of problem
areas reflects the ETOPS real-time maintenance philosophy.
SUMMARY
Although three- and four-engine Boeing airplanes (as well as some earlier 737s) are not
specifically designed or improved for ETOPS, the ETOPS maintenance approach can be
applied to those airplanes and offer operators significant improvements in reliability,
performance, and dispatch rates. The approach can be applied at minimal cost, which
can later be offset by reduced maintenance costs and other costs associated with
diversions or turn backs..
ETOPS
CFMI Proprietary Information. 75

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