L PYLON LOOP FAIL
(Advisory)

IASC #1 monitors the left bleed air loop, IASC #2 monitors the right bleed air loop.

• The respective IASC detected a short to ground during the system self-test. The loop resistance is out of tolerance and has posted the cyan 'L PYLON LOOP FAIL' (Advisory) CAS message indicates that the loop is defective.

• L Pylon Bleed Loop (MT063)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW300-30-0354 - Potential Piccolo Tube Damage When Replacing a Bleed Loop Element

Forum Articles/Infoservice/Newsletter: None

L Pylon Bleed Loop schematic and information

Troubleshooting Guide for Bleed Loops

NOTE: If the bleed loop resistance value is within limits, try cleaning the bleed loop connections per AMM 51-25-00-110-801 and then reapply lubrication to the connections per AMM WM 20-20-00. Lubrication part number is called out in each bleed loop installation procedure. Run the aircraft after the cleaning and applying lubing procedure and see if the BLEED LOOP FAULT clears.

1. If no fault is shown or the system is intermittent, do the following steps:

   1. Go into the LRU Index/Operations and select IASC #1 channel B to display the IASC Channel B menu. Select Leak Detection Test. The test page will provide pages to perform a leak detection system test and check past event locations. The test will check all of the loops the IASC is monitoring and pass or fail them. This test may fail if there is a lot of action going on in the IASC, retesting may pass the failed loops. This test is disabled with the wing heat system ON. Perform the test of the bleed air leak detection loops IAW AMM 36-21-00-710-801.
   2. Perform Initiation Test of the Bleed-Air Leak-Detection Loops. This test will identify if the respective loop has a short or open. Per AMM 36-21-00-740-801
   3. If a loop fails, or a fault has been logged into the MDC, use the steps below to further isolate the condition.

2. Interrogate the MDC as follows:

   1. On the cursor control panel, ensure the toggle switch is to the right and select Anti-Ice, ECS and Fuel buttons simultaneously. The MDC main menu should now be displayed on Display Unit #3.
   2. Using the joystick, select Current Faults (if the fault is active) or Aircraft History to research stored faults. From Aircraft History you can then select Fault Message History and locate the fault. Going into advanced diagnostics will provide an equation id for the fault identified.
   3. Select the MDC fault or equation from the drop down below to provide additional information to assist in troubleshooting.
      Select an MDC Fault Code/Message:B3-007092 - SHORT CIRCUIT [L PYLON LOOP]B3-007093 - OPEN CIRCUIT [L PYLON LOOP]