What was found
NR 5 SPOILER ON THE LEFT WING DOES NOT FULLY RETRACT. MECHANICS FOUND NO COCKPIT INDICATIONS OF A SYSTEM FAILURE OR FAULT MESSAGES IN THE CMC. REPLACING NR 5 SPOILER PCU DID NOT CORRECT THE PROBLEM. FURTHER TROUBLESHOOTING FOUND ACTUATOR CONTROL ELECTRONICS UNIT (ACE), P/N 488550-09-01, IN THE L2 POSITION TO BE AT FAULT. ACE L2 WAS REPLACED AND ALL TESTS PASSED PER AMM 27-02-02. UAL NOTES LEAR SERVICE BULLETIN 488550-27-02 HAD NOT YET BEEN ACCOMPLISHED ON THIS UNIT. SHOP TESTING AND ENGINEERING ANALYSIS OF THIS ACE FAILURE MODE WILL BE ACCOMPLISHED BY BOEING AND LEAR ASTRONICS.