What was found
AIRCRAFT WAS GROUNDED: DURING FLIGHT AT CRUISE AT FL 210 USING ALL AUTOMATION CONTROL, WHILE REDUCING SPEED THE AUTO THROTTLE REDUCES THE POWER THEN THE GEAR HORN GOES OFF AND THE 3 GEAR RED LIGHTS COME ON. REMOVED AND REPLACED SPOILER CONTROL UNIT (AALA202504176310), PER AMM 27-61-45. ACCOMPLISHED PSEU CHECK AND TEST PER AMM 32-09-10. ACCOMPLISHED LMP TEST PER GPM 16-10. ACCOMPLISHED TSI MIC 0113390. ALL TEST PASSED. REMOVED AND REPLACED PSEU (AALA202504226211), PER AMM 27-61-45. ALL TEST PASSED.