What was found
(CAN) DURING TAXI THE A/C REQUIRED MORE THAN NORMAL POWER TO TAXI.DURING T.O. ROOL AT 80KTS, DECISION TAKEN BY CREW TO ABORT. A/C TAXIED BACK TO LINE WHERE CREW NOTICED BRAKE FIRE. INITIAL INVESTIGATION REVEALED BRAKE CONTROL VALVE FAILURE. UNCOMMANDED APPLICATION TO BOTH BRAKES WITHOUT EICAS MASSAGE. CONTROL UNIT UNDER INVESTIGATION BY CRANE AND LEARJET. MOD TO BCU TO PREVENT THIS ALSO ON GLOBAL EX.