What was found
NR 1 ENGINE FAILED TO START. EGT HUNG UP AT APPROXIMATELY 450C, THEN ROLLED BACK. GROUNDED-YES. VERIFIED FROM PILOTS PACKS WERE OFF DURING ENGINE START. PERFORMED B737-800 FIM 80-50 TASK 806 STEP FOUND 2 MESSAGE NUMBER 75-20411, 75-10411 THE HPTACC POSITION SIGNAL AS DISAGREE, REF LP 60004863 LT PACK DISCRETE SHOWS ON WHEN SWITCH OFF. ACCOMPLISHED B737-800 FIM 80-05 TASK 806 E(1), F(2) THROUGH F(5) AND (F)7 NO DEFECTS NOTED. HPTACC ECONOMIC FAULT TRANSFERRED TO LP 60004864 EEC TEST GOOD, REF B737-800 AMM 73-21-00 IGNITION TEST GOOD, REF AMM 74-00-00-750-801-F00. REMOVED AND REPLACED NR 1 ENGINE SPAR VALVE ACTUATOR OPERATIONS CHECKED OK, REF AMM 28-22-11-000-804 AND AMM 28-22-11-400-804 STARTED AND RAN NR 1 ENGINE ALL INDICATIONS NORMAL, REF AMM 71-00-00-800-808-F00.