Date: 201907
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked; Taxi
Aircraft component: Engine Air Pneumatic Ducting
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Time Pressure; Workload
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Procedure; Human Factors; MEL
Primary problem: Aircraft

Narrative: The aircraft that was brought to us had a maintenance write up just previous to our flight for a Bleed 1 Leak during taxi; it was cleared with a 'performed ops (operation) reset of bleed sys (system) per mx (Maintenance) control'. Upon taxiing out we experienced the same bleed leak issue. Maintenance Control initially wanted us to MEL the #1 Pack. Since the flight deck temperature had already reached 35C with both packs cooling the aircraft. I felt it unwise to accept the aircraft with just the number #2 pack providing cooling (the #2 pack predominantly provides cool air to the cabin).After returning to the gate and de-planing the passengers we did an engine run and taxi in order to troubleshoot the issue. The engine run was performed with Bleed #1 selected off and no issues were noted at that time. Contract Maintenance initially deferred the bleed system via MEL 36-XX-XX-X; securing the LH engine bleed air system closed. At the recommendation of the Contract Mechanic; we attempted to perform an engine run at the gate with both the engines. On the first attempt to start engine #2 (which we typically start first) the APU automatically shut itself down (there are multiple write-ups in the maintenance logbooks for this APU issue) midway through the engine start sequence; this caused an aborted start of the #2 engine due to a hot start condition. I entered the APU discrepancy in the aircraft logbook and we restarted the APU per Maintenance Control's request; dry motored engine #2 and restarted it in accordance with the QRH. Engine #2 started normally on the second attempt with the APU operating normally. We then started engine #1; everything indicated normal and no bleed #1 leak was noted. Still at the gate; with the maintenance paperwork being completed; we encountered another bleed leak warning. Only this time; no engines were running (just the APU) and Pack #1 was selected in the off position. Maintenance Control instructed the Contract Mechanic to undo the previously performed Bleed #1 MEL. The corrective action was noted as 'Found leak to be caused by Pack 1. Bleed Valve secured open MEL cleared. Placard Removed' He was then instructed to MEL Pack #1 instead. I feel that the Pack #1 MEL did not make sense as Pack #1 had been de-selected prior to the last Bleed #1 leak Warning (Each warning we encountered resulted in a Master Warning; EICAS message and the LEAK inscription on the Bleed Selector illuminating). Maintenance Control mentioned that this was part of the 'trouble shooting'; which did not sit well with me. I felt uneasy with Maintenance Control's multiple application of MEL's as a trouble shooting solution; particularly when the choice was made to MEL a system that was not operable when the final bleed leak occurred. To my knowledge; no inspection was ever made or noted in the maintenance log for any additional damage that may have occurred as a result of the bleed leak. Considering how catastrophic a bleed leak could be in-flight and with all above mentioned factors; both my First Officer and I felt the safest course of action was to refuse the aircraft.




Synopsis: ERJ145 Captain reported multiple MEL's and aircraft system failures at gate forced flight crew to refuse aircraft.