W DOC AIRBUS | TSM A320F

APU AUTO SHUTDOWN - SENSOR FAILURE, Oil Pressure Detection failed (131-9(A))

TASK 49-00-81-810-818-A
APU AUTO SHUTDOWN - SENSOR FAILURE, Oil Pressure Detection failed (131-9(A))

1. Possible Causes
  • LOW OIL PRESSURE SWITCH SHOWS OPEN CIRCIUT
  • OIL LEVEL SHOWS LOW
  • oil level
  • damage/contamination of the electrical connector P14
  • LOW OIL PRESSURE SWITCH (P14)
  • ELECTRONIC CONTROL BOX [59KD]
  • LOW OIL PRESSURE SWITCH (8091KM)
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
AR
MULTIMETER - STANDARD
 B. Referenced Information
REFERENCE
DESIGNATION
AMM 49-00-00-860-008
APU Start by External Power
ASM 496104
AMM 49-61-34-000-003
Removal of the Electronic Control Box (ECB) (131-9(A))
AMM 49-61-34-400-003
Installation of the Electronic Control Box (ECB) (131-9(A))
AMM 49-90-00-600-007
Check Oil Level and Replenish (131-9(A))
AMM 49-94-14-000-003
Removal of the Low Oil Pressure Switch (131-9(A))
AMM 49-94-14-400-003
Installation of the Low Oil Pressure Switch (131-9(A))
3. Fault Confirmation
Subtask 49-00-81-710-122-A ** ON A/C NOT FOR ALL
A. Read-out of ECB Trouble-Shooting Data
   (1) Put the APU MASTER SW to the ON position.
   (2) Get access to the APU SHUTDOWN report.
   (3) Push the '>' adjacent to LRU DATA:
  • the MCDU menu shows
    LOW OIL PRESSURE SWITCH SHOWS OPEN CIRCIUT

    OIL LEVEL SHOWS LOW

   (4) Start the APU and apply Bleed Air for 20 seconds, minimum AMM 49-00-00-860-008.
4. Fault Isolation
Subtask 49-00-81-810-092-A ** ON A/C NOT FOR ALL
A. If an APU auto shutdown occurs during the APU operation and the APU SHUTDOWN report gives the maintenance message:

SENSOR FAIL
LOW OIL PRESS SW P14
LOW OIL LEVEL

associated with the Fault Code Number (FCN) 98 or 99

  • do a check of the oil level in the APU oil reservoir AMM 49-90-00-600-007 and
    do a check for damage/contamination of the electrical connector P14 of the LOW OIL PRESSURE switch (P14).
   (1) If the electrical connector of the LOW OIL PRESSURE SW (P14) is damaged/contaminated:
  • do a repair/cleaning.
   (2) If the electrical connector is OK:
  • use a MULTIMETER - STANDARD to do a resistance check across pin 1 and pin 2 of the LOW OIL PRESSURE SW (P14).
     (a) If the resistance value is > 10 Ohms:
     (b) If the resistance value is < 10 Ohms:
  • do a check of the aircraft wiring from
    the ECB (59KD) AB/C5 to the LOW OIL PRESSURE SW (P14) P14/1
    and
    the LOW OIL PRESSURE SW (P14) P14/2 to GND
    ASM 496104.
       1 If the fault continues:
Subtask 49-00-81-810-092-B ** ON A/C NOT FOR ALL
A. If an APU auto shutdown occurs during the APU operation and the APU SHUTDOWN report gives the maintenance message:

SENSOR FAIL
LOW OIL PRESS SW(8091KM)
LOW OIL LEVEL

associated with the Fault Code Number (FCN) 98 or 99

  • do a check of the oil level in the APU oil reservoir AMM 49-90-00-600-007 and
    do a check for damage/contamination of the electrical connector P14 of the LOW OIL PRESSURE SW (8091KM)
   (1) If the electrical connector of the LOW OIL PRESSURE SW (8091KM) is damaged/contaminated:
  • do a repair/cleaning.
   (2) If the electrical connector is OK:
  • use a MULTIMETER - STANDARD to do a resistance check across pin 1 and pin 2 of the LOW OIL PRESSURE SW (8091KM)
     (a) If the resistance value is > 10 Ohms:
     (b) If the resistance value is < 10 Ohms:
  • do a check of the aircraft wiring from
    the ECB (59KD) AB/C5 to the LOW OIL PRESSURE SW (8091KM) P14/1
    and
    the LOW OIL PRESSURE SW (8091KM) P14/2 to GND
    ASM 496104.
       1 If the fault continues:
Subtask 49-00-81-710-123-A ** ON A/C NOT FOR ALL
B. Do the test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:34:33 UTC
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