Message Name:

[ACSC1-A] LH PCK DIS UNDERPRESSURE

Message Code:

2161519ECS

The Pack Discharge Pressure has been detected being less than the cabin pressure.

• Anti-Icing Pressure Sensor 1 (MT64)/Pack Discharge Pressure Sensor (PDPS)
• Air Conditioning System Controller 1 (ACSC) (A87)
• Air Cycle Machine (ACM)
• Pack Inlet Flow Sensor 1 (MT66)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

NOTES:

• "L PACK FAIL" Caution message on descent may be a sign of water in accumulation in the PDPS sense line. The same message happening on climb may indicate a leak in the sense line.

1. Inspect the ducts located between the air cycle machine and the bulkhead for damage or disconnected connections.
2. Inspect the anti-icing pressure sensor sense-lines for proper installation, damage and make sure sense hole is not obstructed.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.
      

3. Blow clean dry compressed air through the sense line of the anti-icing pressure sensor to remove any water or FOD. (Make sure ice is melted).

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

4. Inspect the air cycle machine (ACM) anti-ice port on the ACM make sure the port has no blockage.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.
      

5. Examine the air cycle machine drain lines for blockage.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

6. Examine the water extractor drain lines for blockage.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

7. Examine the water extractor for damage.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

8. If the pilot report any problems with keeping a comfortable zone temperature (zone temperature too hot), then perform the pack performance task of the pack that was running hot.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

9. Interchange Pack Inlet Flow Sensors.

   1. If system checks are good, replace Pack Inlet Flow Sensor 1 and do close out.
   2. If fault remains, continue with next step.

10. Interchange ACSCs.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

11. Check wiring between PDPS and ACSC.
12. Do close out.