Narrative:

On preflight we cleaned all the snow and ice from the engine intakes. About 10 minutes after engine start while waiting in the deice line we heard a loud but muffled 'bang' noise from the rear of the aircraft. Almost immediately following the bang noise one or both engines began to spool up. We immediately shutdown the engines and turned off the batteries to remove all electrical power from the aircraft.we phoned [dispatch] and [maintenance]; unsure of what we had just experienced. We were unsure if we had a compressor stall or maybe a bleed air duct had come loose. There was no sign of any malfunction on the exterior or the aircraft and there were no cas messages displayed.later that evening I followed up with [maintenance] and was told that they found that water had intruded on the air conditioning controller box in the aft electronics bay causing it to short out. I was sent the photo taken by the mechanic and only then did I realize how fortunate we were to have had this occur on the ground as opposed to IMC in the mountains; which is where we were headed at the time.when the maintenance controller also told me that this had been seemingly caused by water intrusion it reminded me that this plane had previously been written up for a wet baggage compartment ceiling that was signed off as could not duplicate.I'm not sure how the water entered the aircraft; however it concerns me that this was brought to the attention of maintenance by a previous crew yet it was signed off with no fix. This uncorrected leak then seemingly resulted in the hazardous electrical situation we experienced.secondly; I'm concerned that a leak of water can result in a potentially catastrophic electrical failure. Embraer needs to find a better way to seal these components from water intrusion. We were fortunate that we were on the ground and were able to remove power immediately. It concerns me to think about how this may have played out had we been airborne and unable to just shut the plane down.

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Original NASA ASRS Text

Title: The Captain of an Embraer EMB-505 reported that during taxi they heard a loud bang; causing both engines to spool-up so they shut down the engines and turned off all electrical.

Narrative: On preflight we cleaned all the snow and ice from the engine intakes. About 10 minutes after engine start while waiting in the deice line we heard a loud but muffled 'bang' noise from the rear of the aircraft. Almost immediately following the bang noise one or both engines began to spool up. We immediately shutdown the engines and turned off the batteries to remove all electrical power from the aircraft.We phoned [Dispatch] and [Maintenance]; unsure of what we had just experienced. We were unsure if we had a compressor stall or maybe a bleed air duct had come loose. There was no sign of any malfunction on the exterior or the aircraft and there were no CAS messages displayed.Later that evening I followed up with [Maintenance] and was told that they found that water had intruded on the air conditioning controller box in the aft electronics bay causing it to short out. I was sent the photo taken by the mechanic and only then did I realize how fortunate we were to have had this occur on the ground as opposed to IMC in the mountains; which is where we were headed at the time.When the maintenance controller also told me that this had been seemingly caused by water intrusion it reminded me that this plane had previously been written up for a wet baggage compartment ceiling that was signed off as could not duplicate.I'm not sure how the water entered the aircraft; however it concerns me that this was brought to the attention of maintenance by a previous crew yet it was signed off with no fix. This uncorrected leak then seemingly resulted in the hazardous electrical situation we experienced.Secondly; I'm concerned that a leak of water can result in a potentially catastrophic electrical failure. Embraer needs to find a better way to seal these components from water intrusion. We were fortunate that we were on the ground and were able to remove power immediately. It concerns me to think about how this may have played out had we been airborne and unable to just shut the plane down.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.