CFM56-5B TRAINING MANUAL

 
THRUST REVERSER Pressure switch failures.
Two pressure switches in the HCU, one dedicated to channel A and the other to channel B, indicate if the system is pressurized.
The state of the switches is as follows :
- Switch open = System pressurized.
- Switch closed = System not pressurized.
The ECU detects failures of the pressure switches by comparing the switches status across the CCDL. If channel A and B switches are both available, but disagree with one another, a pressure switch fault is generated.
The ECU also detects if both pressure switches have failed open. This fault detection is active if the
thrust reverser shut-off valve is installed, the reverser is commanded to the stow position and the TRPV is commanded unpressurized.
Typical fault message.  TR PR SW, J5/J6, ECU
 
Inadvertent pressurization.
Unless the thrust reverser is detected inhibited, the ECU automatically selects forward idle when in flight, or on ground, for any of the following cases :
- 4 doors detected unstowed.
- At least 1 door detected unstowed and thrust
reverser inadvertently pressurized.
- In case of an indeterminate state and thrust reverser inadvertently pressurized.
The thrust reverser is considered inadvertently pressurized when either the local, or cross channel pressure switches indicate that the system is pressurized for at least 360ms and the TRPV and TRDV are both commanded off.
Once inadvertent pressurization has been detected, this state remains latched unless both pressure switches indicate unpressurized, or the TRDV is energized (deploy), or the ECU is reset.
 

EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION FAULT DETECTION
FAULT DETECTION
& ANNUNCIATION Page 46
Nov 02
  
 
  CFM56-5B TRAINING MANUAL

TYPICAL FAULT MESSAGE : "TR PR SW, J5/J6, ECU"
CTC-231-040-00 HCU PRESSURE SWITCHES
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION FAULT DETECTION
FAULT DETECTION
& ANNUNCIATION Page 47
Nov 02
  
 
  CFM56-5B TRAINING MANUAL

 
THRUST REVERSER
Stow switches.
The ECU interfaces with 8 stow switches (1 double switch per T/R door), connected in 2 identical parallel circuits
of 4 switches. Each parallel circuit of 4 stow switches provides 2 inputs to the ECU. Both ECU channels have direct hardwired access to both parallel circuits inputs. The inputs are designated TRS1 and TRS2.
　
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