Narrative:

Captain met inbound first officer on jet bridge and first officer mentioned the brake temps were a bit strange but it was probably due to the deferral of the BSCU1. Crew boarded aircraft and indeed noticed brake temps were 'strange' in that the number 1 and 4 wheels were hot and the 2 and 3 wheels were at least 220 degrees C cooler. This is odd in that the two wheels per truck are usually warm but neither crew member recalled seeing the outside ones hot and the inside ones cool. Winds at the airport were straight down the runway. The temperatures were within parameters outlined in the flight manual; but the configuration of the temperatures caused us to enter a maintenance item for further investigation by maintenance. The mechanic physically felt the brakes and confirmed the brake temps were accurate (hot/cold). The mechanic observed the brakes operating and signed off the item. Checks were done per the deferral item and the door was closed for departure. A discussion in the cockpit still revealed some question as to the brake operation so maintenance was contacted for further info. Maintenance pointed crew toward the aids system page where the pressure values for brakes 2 and 3 were blank. Maintenance told us they should be equal across all the brakes. Maintenance contacted station maintenance to return for further troubleshooting. After much testing it was determined the best course of action would be to clear the deferred item for dispatch as all parties agreed there was an unidentifiable fault with the brakes. The cids prior legs pages identification'd some brake valve faults from previous legs. It is the belief of the crew that the aircraft flew at least one leg with the inner brakes of both main wheels operating at diminished or zero operating capacity. This could have been problematic if faced with a rejected takeoff. Parts could not be secured so the flight was canceled by maintenance. The outbound crew believes the inbound crew should have reported their concerns of the brake system to maintenance. There is no mention of the fault they observed in the deferral or the MEL. If the outbound crew had arrived at the aircraft after a period of time that had allowed the brakes to cool; this mechanical issue might not have been discovered until it was too late. It is quickly becoming an unwritten SOP to report discrepancies to the 'outbound' crew so that they can report them inbound to a mechanic station. This procedure is not allowable by flight manual and should be strongly discouraged. The question of 'did you write it up' should not have to be asked as it is clearly directed by air carrier policy to do so.

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Original NASA ASRS Text

Title: An A320's BSCU1 was previously deferred because of strange brake temperature indications but the flight crew's investigation with maintenance determined that brakes 1 and 4 were operating normally while brakes 2 and 3 may have been symmetrically not activated.

Narrative: Captain met inbound First Officer on jet bridge and First Officer mentioned the brake temps were a bit strange but it was probably due to the deferral of the BSCU1. Crew boarded aircraft and indeed noticed brake temps were 'strange' in that the number 1 and 4 wheels were hot and the 2 and 3 wheels were at least 220 degrees C cooler. This is odd in that the two wheels per truck are usually warm but neither crew member recalled seeing the outside ones hot and the inside ones cool. Winds at the airport were straight down the runway. The temperatures were within parameters outlined in the Flight Manual; but the configuration of the temperatures caused us to enter a maintenance item for further investigation by Maintenance. The mechanic physically felt the brakes and confirmed the brake temps were accurate (hot/cold). The mechanic observed the brakes operating and signed off the item. Checks were done per the deferral item and the door was closed for departure. A discussion in the cockpit still revealed some question as to the brake operation so maintenance was contacted for further info. Maintenance pointed crew toward the AIDS system page where the pressure values for brakes 2 and 3 were blank. Maintenance told us they should be equal across all the brakes. Maintenance contacted Station Maintenance to return for further troubleshooting. After much testing it was determined the best course of action would be to clear the deferred item for dispatch as all parties agreed there was an unidentifiable fault with the brakes. The CIDS prior legs pages ID'd some brake valve faults from previous legs. It is the belief of the crew that the aircraft flew at least one leg with the inner brakes of both main wheels operating at diminished or zero operating capacity. This could have been problematic if faced with a rejected takeoff. Parts could not be secured so the flight was canceled by maintenance. The outbound crew believes the inbound crew should have reported their concerns of the brake system to Maintenance. There is no mention of the fault they observed in the deferral or the MEL. If the outbound crew had arrived at the aircraft after a period of time that had allowed the brakes to cool; this mechanical issue might not have been discovered until it was too late. It is quickly becoming an unwritten SOP to report discrepancies to the 'outbound' crew so that they can report them inbound to a mechanic station. This procedure is not allowable by Flight Manual and should be strongly discouraged. The question of 'did you write it up' should not have to be asked as it is clearly directed by Air Carrier policy to do so.

Data retrieved from NASA's ASRS site as of April 2012 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.