Date: 201506
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Pneumatic System - Indicating and Warning
Component problem: Design; Malfunctioning
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Training / Qualification; Time Pressure; Confusion; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Human Factors; MEL
Primary problem: Human Factors

Narrative: When I [Maintenance Controller X] came on duty the L BLEED LEAK WARNING was being reported by phone by the flight crew. I called outstation Maintenance to come to the aircraft to try to find the cause of the indication. We checked the Maintenance Diagnostic Computer (MDC) for evidence and found none but ran a Bleed Leak Event Location test. The results of the test indicated a leak or false indication in the APU bleed air duct between the APU bulkhead and the Isolation Valve at the Crossover duct. The Mechanic inspected the duct and bleed [Overheat Warning] loops and could not find any defects. We then ran the APU at the gate; supplying air for a considerable length of time and could not duplicate the fault. The aircraft was released with no faults found. An hour or more later the warning came back. The Mechanic was still in the area so I had the crew shut down the APU and use an airstart to run the engines. My involvement ended at this point in the event because I became involved in some other problem. My comment to the Maintenance Operations and Duty Manager (MOD) at this point was that I suggested we find another aircraft for the flight because we could not effectively troubleshoot this 'warning' problem without a 'break out box' and some other tooling and parts. I felt we were either proving a leak in the APU ducting or a false warning in that area at this point. The next thing I knew the APU was deferred and the aircraft was released.Maintenance Controller Z told me when I came in for work the next week that he had been requested to submit a report because the deferral of the APU was deemed inappropriate. There was a lot of discussion in the office between Maintenance Controller Z and the MOD as to the correctness of that and I am not sure where that went. I could not find an acceptable deferral for this fault. The deferrals stipulated that the APU Load Control Valve (LCV) had to function and in the warning condition; it is forced to 'close'; so in my opinion that is 'not working'.....This event transpired over several hours and there was a lot of conversation in the office about how to move the aircraft. My solution was to replace the aircraft and send a roadtrip because I do not feel that outstation Maintenance can effectively troubleshoot a warning in this system without proper tooling and training. I guess I was overruled.I am submitting this ASRS report. My timeline is not firm and there were a lot of other problems at the time. And guess what? I came in to work today and we have the same problem on the same aircraft again. The only difference is the location of the aircraft. It is even showing the same locations again in the Anti-Ice Leak Detection Controller (AILC) event location test. Maybe we have a bad AILC? Or we have an actual leak that we have not located yet. There is a significant lack of knowledge of this system in the Maintenance Control office and '0' experience working on the system other than Maintenance Controller Y and myself. Nobody wants to hear what I have to say about it. I am too conservative and not deemed a 'team player' when it comes to these kind of issues.It is my belief that any time a 'warning' occurs in this system it appears to me that if the system cannot be deferred; it cannot be troubleshot effectively by an untrained; ill equipped outstation Mechanic 'looking it over' and signing it off. If the system is not deferrable then it should demand a roadtrip supported by qualified mechanics with proper training and proper equipment and tooling.

Callback: Reporter stated the 'break-out box' is an interface tool that allows Maintenance to troubleshoot the Overheat Warning Detection (A and B) loops via the AILC Controller while outside of the very tight Avionics compartment on CRJ-900 aircraft. He believes that 90 % of the reliability issues at the gate involve false overheat warning EICAS messages caused by the loop sensing element connectors that use steel with ceramic insulators. The ceramic insulation is prone to cracking and will then bleed electrons; sending spurious; false warnings of a pneumatic leak through the Bleed Leak Detection System. The warning loops and connectors start in the Aft Equipment Bay and connect at the fuselage flat pressure bulkhead using 90-degree angle connectors and then run alongside the length of the fuselage APU duct; out to the wings; and engine pylons.Reporter stated that in the aircraft he reported about; two pneumatic leaks were eventually located at insulated duct clamps connecting the APU pneumatic duct manifold along the internal fuselage and the other leak was isolated in the Aft Equipment Bay. Another CRJ-900 recently had three air returns caused by one of the Overheat Warning loop elements had made contact with a wing anti-ice duct.



Synopsis: A Maintenance Controller reports about events surrounding an inappropriate deferral of an APU for an EICAS L BLEED LEAK WARNING on a CRJ-900 aircraft at an outstation gate. Controller also noted the significant lack of knowledge maintenance controllers have of the pneumatic system; the untrained; ill equipped outstation mechanics; and the lack of effective troubleshooting the cause of the EICAS warning.