Date: 201203
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Takeoff / Launch
Aircraft component: Generator Drive
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Other / Unknown
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Confusion; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Other Takeoff Roll
Result: Flight Crew Returned To Gate; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: I took a radio call from a B757-200 aircraft advising he lost his Left Generator on takeoff roll and Rejected Takeoff (RTO) at approximately 60 KTS. Then the generator came back online during taxi and he asked if I would look and see if there is any history on the generator. I looked up the aircraft history and advised him there was none. I did ask him to do an [Engine] Run-up because I wanted to see if the generator would remain online during the Run-up and then I could pass on the information to Maintenance. I did tell him he could continue and I think this is where my miscommunication occurred. At this point I should have just told him to return to the gate since it was already an RTO. (When I said continue; I should have not used that verbiage because my intent was for him to return to gate; and then continue on after Maintenance was performed or the generator placed on MEL. (I should not have assumed he would have known to go back to gate; and I may have given the impression to continue on flight.) I did call the Maintenance Tower and asked if he was aware the flight was returning and he said 'yes'; that it was assigned a gate on 'B' Gates; leading me to understand the flight just returned to the gate.Line Maintenance called to obtain Dispatch approval on the Generator (Gen) MEL which was granted. I then was asked by the Maintenance Control Shift Manager if the flight did a second Rejected Take Off due to [his] hearing the [pilot] did; I told him not to my knowledge. When the log sheets came across; I noticed the crew write-up stated: 'L GEN DRIVE MSG COMES ON DURING T/O ROLL AT APPROX 70-74 KTS - OCCURRED TWICE- 2 REJECTED T/Os'. At that time; I advised Maintenance Control Shift Manager the crew did state in logbook write-up there was a second Rejected Takeoff.

Callback: Reporter stated mis-communication between he and their B757-200 pilot was definitely a factor that contributed to another attempted takeoff that ended in a second RTO for the same Left Engine generator failing and a return to gate. Maintenance changed an electrical Bus Power Control Unit (BPCU) that was faulting.



Synopsis: A Maintenance Controller describes how mis-communications between he and a B757-200 pilot contributed to the pilot attempting another takeoff that ended with a second RTO for the same Left Engine Generator failure. Aircraft returned to gate and Maintenance replaced the Bus Power Control Unit (BPCU).