Narrative:

On the date in question; we did in fact return to field for an unrelated issue due to the cargo bottle self discharging in flight. Upon landing; the brakes seemed less effective. To be fair; there was one thrust reverser inoperative on MEL and with that consideration; it did not seem that unusual that the aircraft deceleration was reduced slightly. However; upon landing; the number 1; 2 and 3 brakes heated up to 5's on the btms while the #4 brake was still indicating a 1. Btms is the brake temperature monitoring system that tells the crew not only that the brakes are working but how hot they are in increments of 32 degrees C per number. The number 5 on a btms for a given brake would indicate a brake at a temperature of approximately 160 degrees C. After the aircraft was parked at the gate a post inspection was completed to include a through inspection of the brakes. All brakes appeared to be as indicated (hot) to include the #4 brake unusually cool (to the touch). Maintenance was already at the aircraft to replace the cargo fire bottle and the cool brake was mentioned to them at that time. The maintenance employee took a quick look at the #4 brake and confessed to me that the problem was obvious; the top cannon plug was unscrewed to the point of almost being disconnected completely. It should be mentioned that on this particular flight; destined for one of our shortest landing runways with not only one reverser inoperative (MEL) but also; a brake as well; this could have been a very unsafe event if the aircraft could not be stopped prior to the runways end.although it is possible that the cannon plug may have 'backed' itself off; it is my understanding that those plugs are safety wired to prevent this. The brake was new and probably replaced a short time before the aircraft was assigned to my flight. Shortly could be a day or days prior. It is my observation that the brake was replaced and not properly secured and tested at the time of installation. The only suggestions that I have at this point is this: first; research into when and who actually handled the #4 brake last and second; a determination of how this could have happened. Lastly; accountability for the problem.

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Original NASA ASRS Text

Title: CRJ200 Captain reports noticing after landing that the number four brake did not heat up at all during the landing. Maintenance discovers the cannon plug for that brake is unscrewed and was likely not installed correctly after a recent brake replacement.

Narrative: On the date in question; we did in fact return to field for an unrelated issue due to the cargo bottle self discharging in flight. Upon landing; the brakes seemed less effective. To be fair; there was one thrust reverser inoperative on MEL and with that consideration; it did not seem that unusual that the aircraft deceleration was reduced slightly. However; upon landing; the number 1; 2 and 3 brakes heated up to 5's on the BTMS while the #4 brake was still indicating a 1. BTMS is the Brake Temperature Monitoring System that tells the crew not only that the brakes are working but how hot they are in increments of 32 degrees C per number. The number 5 on a BTMS for a given brake would indicate a brake at a temperature of approximately 160 degrees C. After the aircraft was parked at the gate a post inspection was completed to include a through inspection of the brakes. All brakes appeared to be as indicated (hot) to include the #4 brake unusually cool (to the touch). Maintenance was already at the aircraft to replace the cargo fire bottle and the cool brake was mentioned to them at that time. The Maintenance employee took a quick look at the #4 brake and confessed to me that the problem was obvious; the top cannon plug was unscrewed to the point of almost being disconnected completely. It should be mentioned that on this particular flight; destined for one of our shortest landing runways with not only one reverser INOP (MEL) but also; a brake as well; this could have been a very unsafe event if the aircraft could not be stopped prior to the runways end.Although it is possible that the cannon plug may have 'backed' itself off; it is my understanding that those plugs are safety wired to prevent this. The brake was new and probably replaced a short time before the aircraft was assigned to my flight. Shortly could be a day or days prior. It is my observation that the brake was replaced and not properly secured and tested at the time of installation. The only suggestions that I have at this point is this: First; research into when and who actually handled the #4 brake last and second; a determination of how this could have happened. Lastly; accountability for the problem.

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.