What was found
FIRST CSS OF APU RESULTED IN FAILED START AND APU FAULT LIGHT. ALTITUDE OF 37,000. FAULT LIGHT WENT OUT AFTER QRH PROCEDURE AND 3 MIN. SECOND CCS AT FL 350 WAS SUCCESSFUL. PERFORMED APU BITE TEST - FOUND CODE 49-41010 NO ACCELLERATION SHUTDOWN. PERFORMED FIM TASK 49-40-00-810-801 APU START NORMAL ON GROUND. TECH SERVICES REQUESTS FOLLOW UP. R & R THE APU IGNITER PLUG IAW AMM 49-41-51& REPLACED THE APU IGNITER PLUG LEAD IAW AMM 49-41-52. R & R APU EXCITER UNIT. REF MM 49-41-31-000-801, MM 49-41-31-400-8001. FLT CREW REPORTS CSS PASSED.