Narrative:

We received a gate call for a 'flap low speed' message. We verified the fault when we arrived at the aircraft and proceeded to place a flap channel on MEL. We checked the maintenance section of the MEL to see if there was guidance to verify which channel was inoperative; there was no guidance found. We went through a procedure of pulling circuit breakers (C/bs) to verify which channel we should defer; this is how we determined to defer channel two. The maintenance function was completed for the MEL of flap channel two and the flaps operations checked 'good' with channel one in command (no 'flap fail' message). Maintenance control was contacted by me to place flap channel two on MEL. At this time I went over the procedure with maintenance control to verify the steps used to determine which channel was to be deferred and I was comfortable that we checked it properly and proceeded to defer flap channel two. The aircraft left ZZZ for ZZZ1 and on approach to ZZZ1; the aircraft flaps failed and the aircraft diverted to ZZZ2. MEL book was used. Checked the maintenance procedure section of the MEL book on how to properly determine which channel was faulty. No information was provided by the MEL book; at that time I contacted maintenance control for guidance on determining faulty channel. I misunderstood information given by maintenance control which led to improper channel being placed on deferral. [Recommend] more detail in the maintenance section of the MEL for figuring out which channel was inoperative. Reference material not clear. [Scheduled departure] pressure.

Related reports:

Google
 

Original NASA ASRS Text

Title: A Line Mechanic describes his efforts to troubleshoot and determine whether Flap Channel One; or Channel Two had failed after a 'Flap Low Speed' message appeared on an ERJ-145 aircraft. Aircraft later diverted due to flaps failed again on approach. Incorrect Flap Channel had been deferred.

Narrative: We received a gate call for a 'Flap Low Speed' Message. We verified the fault when we arrived at the aircraft and proceeded to place a Flap Channel on MEL. We checked the maintenance section of the MEL to see if there was guidance to verify which channel was inoperative; there was no guidance found. We went through a procedure of pulling Circuit Breakers (C/Bs) to verify which channel we should defer; this is how we determined to defer Channel Two. The maintenance function was completed for the MEL of Flap Channel Two and the flaps operations checked 'good' with Channel One in command (no 'Flap Fail' message). Maintenance Control was contacted by me to place Flap Channel Two on MEL. At this time I went over the procedure with Maintenance Control to verify the steps used to determine which channel was to be deferred and I was comfortable that we checked it properly and proceeded to defer Flap Channel Two. The aircraft left ZZZ for ZZZ1 and on approach to ZZZ1; the aircraft flaps failed and the aircraft diverted to ZZZ2. MEL book was used. Checked the maintenance procedure section of the MEL book on how to properly determine which channel was faulty. No information was provided by the MEL book; at that time I contacted Maintenance Control for guidance on determining faulty channel. I misunderstood information given by Maintenance Control which led to improper channel being placed on deferral. [Recommend] more detail in the maintenance section of the MEL for figuring out which channel was inoperative. Reference material not clear. [Scheduled departure] pressure.

Data retrieved from NASA's ASRS site as of July 2013 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.