TRIM AIR LEAK
(Warning)

DDG Reference:	36-20-01
Pilot Action (QRH):	ENVR 06-5
System Description:	21-52-00 - Air Conditioning System 30-12-00 - Wing Anti-Ice System 36-20-00 - Indicating System
Schematic Diagram:	SSM 36-21-00-101 - Bleed-Air Leak-Detection System TRIM AIR SCHEMATIC
Wiring Diagram:	WM 36-21-11-1_001 - Sheet 1 - Pack Loop - ALL

A red 'TRIM AIR LEAK' (Warning) Crew Alerting System (CAS) message indicates a leak has been detected in the bleed air ducting down stream of the Right Flow Control Valve 2, up to the Pre-Cooler Cross-Over Valve and up to the Trim Air Check Valve.
NOTE: Flow Control Valve 2 is the top valve as installed.

• The Integrated Air System Controller (IASC) bleed air leak detection loops have detected a leak in the ducting down stream of the Right Flow Control Valve, up to the Pre-Cooler Cross Over Valve and up to the Trim Air Check Valve.
• Through ARINC bus to the Data Concentrator Unit (DCU) the Engine Indication and Crew Alerting System (EICAS) has displayed the red 'TRIM AIR LEAK' warning CAS message.
• The TRIM AIR LEAK is a Single Loop System.

• Right Flow Control Valve (MPE4)
• Pre-cooler Cross-over Valve
• Trim Air Check Valve
• Trim Loop Sensor 1 (MT61)
• Trim Loop Sensor 2 (MT36)
• Trim Loop Sensor 3 (MT69)
• Trim Loop Sensor 4 (MT124)
• Loop Routing Interference

Advisory Wire/Service Bulletin:

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

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

Flight Operation Notifications Manual (FONM): None

NOTES:

• Troubleshooting Guide for Bleed Loops
• Bleed air loops are the detection element used to indicate that a leak has occurred in the bleed air system.

  • The ducting has a insulation cover that will contain the air leaking from the ducting routing it to a insulation vent hole.
  • The loop elements are electrically connected in series and the concentric outer conductor is connected to the aircraft ground. The layer of eutectic salt compound insulates the outer conductor from the inner conductor. When hot bleed-air gets on the loop element, the eutectic salt compound becomes conductive and lets the outer conductor make contact with the inner conductor. The IAS controller senses that the outer conductor is grounded and supplies the inner conductor with alternating current for its resistance measurement. The IAS controller measures this resistance and shows the correct message on the EICAS.
  • The intermediate pressure system loop element senses a bleed-air leak when the temperature is more than 255°F (123.90°C).

Removal of the Flow Control Valve	AMM 21-51-09-000-801
Installation of the Flow Control Valve	AMM 21-51-09-400-801
Removal of the Pre-Cooler Cross-Over Valve	AMM 21-61-07-000-801
Installation of the Pre-Cooler Cross-Over Valve	AMM 21-61-07-400-801
Operational Test of the Pre-Cooler Cross Over Valve	AMM 21-61-07-710-801
Component Location	AMM 36-21-00-992-801
Operational Test of the Bleed-Air Leak-Detection and Warning System	AMM 36-21-00-710-801
Initiation Test of the Bleed-Air Leak-Detection Loops	AMM 36-21-00-740-801
Resistance Check of the Bleed-Air Leak-Detection Loops	AMM 36-21-00-760-801
Removal of the Trim-Air-Supply Leak-Detection Element	AMM 36-21-09-000-801
Installation of the Trim-Air-Supply Leak-Detection Element	AMM 36-21-09-400-801
Removal of the Aft Trim-Air Leak-Detection-Element	AMM 36-21-09-000-802
Installation of the Aft Trim-Air Leak-Detection-Element	AMM 36-21-09-400-802
Removal of the Forward Trim-Air Leak-Detection-Element	AMM 36-21-09-000-803
Installation of the Forward Trim-Air Leak-Detection-Element	AMM 36-21-09-400-803
Removal of the Baggage-Compartment Leak-Detection Element	AMM 36-21-09-000-804
Installation of the Baggage-Compartment Leak-Detection Element	AMM 36-21-09-400-804
Safety Precautions - Maintenance Practices - ALL	SPM 20-00-01-02
Wiring - Maintenance Practices - ALL	SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL	SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL	SPM 20-20-00-02

Going into the system diagnostics to the IASC 2 channel B to display the IASC Channel B menu. The IASC LRU test page will provide pages to perform a leak detection system test and check past event locations.

NOTE: The MDC current fault equation B3-007989 will post with this message identifying only MT36. The MDC does not have the capability to list all of the loops in this multiple loop system, use the troubleshooting below to isolate the leak and section.

1. Locate the short circuit or leak using the Leak Event location function.
2. Check for short circuit at the corresponding connector.
3. Check the loop routing for a fouling condition on a hot surface (loop touching duct).
   NOTE: Before replacing a loop always look at the loop for routing, ensure loop is not too close to the plumbing or the bleed hole on a valve. Review AMM 36-21-00-992-801 for component location. See individual loops for specific routing information.
4. Use a Tegam meter to check capacitance and inductance between the inner and outer conductor of the corresponding loop. Perform the impedance check per the Leak detection how to.

Leak Event Location History

The Leak Event Location History will identify when the system posted a fault, what loop failed and a general location based on an approximate fuselage/wing station location of the overheat condition.
TRIM AIR LEAK

• The 0% location starts at the MT124P2 connector under the floor in the baggage bay and the 100% is at the MT61P1 connector mounted to a bracket on the dual heat exchanger.
• When a location is identified in the leak event location history, Inspect the plumbing for possible leaks.
• If the leak can not be identified, perform the system functional check IAW AMM 36-21-00-710-801.
• The CH350 reports the name of the bleed loop and fuselage station or wing station and general location of the leak in percentage. A 0% location starts at the MT124P2 connector under the floor in the baggage bay and the 100% is at the MT61P1 connector mounted to a bracket on the dual heat exchanger.

Leak Detection Test

The test will check all of the loops the IASC is monitoring and pass or fail them. This test is disabled with the wing anti-ice selected on or if aircraft is woffw. Perform the initiation (IBIT) test of the bleed air leak detection loops IAW AMM 36-21-00-740-801.

• Trim Air loop Information
• Trim Air Loop schematic
• The test will identify if the trim loop has a short or open (greater than 62Ω). MT61, MT36, MT69, MT124 (IASC 2 monitored loop). Check for shorts or open conditions referencing AWM 36-21-11.

TRIM AIR LOOP Reporting

LRU: IASC 2

Total Loop Length: 358 inches for aircraft

Loop identification in the MDC: MT36

Zero point: Connector number MT124P2 under the baggage bay floor

IASC/Loop	Segment ID	Location	FS/WS Start	% MDC Start	" Start	FS/WS End	%MDC End	" End	°C	°F
IASC 2 Trim Air	MT124	Under Baggage Bay Duct	FS660	0%	0"	FS669	12%	41"	124	255
IASC 2 Trim Air	MT69	Fwd Trim Air Duct	FS669	12%	41"	FS756	42%	150"	124	255
IASC 2 Trim Air	MT36	Mid/Aft Trim Air Duct	FS756	42%	150"	FS816	70%	250"	124	255
IASC 2 Trim Air	MT61	Trim Supply Duct (FCV to Pre-cooler)	FS816	70%	250"	FS756	100%	356"	124	255

Select an MDC Fault Code/Message:B3-007989 - TRIM DUCT AIR LEAK [TRIM AIR LEAK]