What was found
(CAN) THE INITIAL PROBLEM REPORTED WAS THAT, WITH APU BLEED ON & BOTH PACKS OPERATING, DUCT PRESSURE WOULD DROP TO APPROX 20 PSI & APU BLEED CAUTION MESSAGE WAS POSTED. APU RPM ALSO DROPPED AND, DURING ENGINE START, APU GEN DROPPED OFF LINE. 1ST ACTION TAKEN WAS TO MEL APU BLEED AIR, BUT THEN A FUEL LEAK WAS NOTICED. A FUEL PIPE AT FCU WAS TIGHTENED BUT FUEL WAS STILL LEAKING. APU WAS PLACED ON MEL AS THERE WAS INSUFFICIENT TIME TO TROUBLESHOOT FURTHER. CLH ENGINEERING SENT A COPY OF AOM 700-062 TO HAMBURG MAINT & REQUIRED THAT FUEL NOZZLES BE INSP FOR CRACKS. THIS WAS DONE & A CRACK FOUND. CRACKED NOZZLE WAS REPLACED & APU WAS TESTED & REINSTATED TO SERVICE.