What was found
LEFT FMC FAILURE AT CRUISE AT CRUISE FAILED AND RECOVERED TWICE WHILE READING QRH. COMPLETED QRH PROCEDURE ON THIRD FAILURE AND RESUMED DUAL FMC OPERATION. FOURTH FAILURE 2 MINUTES AFTER RESTORING DUAL OPS. RE-SELECTED FMC SOURCE SELECT TO BOTH ON RIGHT AND COMPLETED THE FLIGHT SINGLE FMC. GROUNDED - YES. REMOVED AND REPLACED LEFT FLT MANAGEMENT COMPUTER REF B737-900 MM 34-61-02-400-801, OPS NML REF MM 34-61-00-710-801 AND MM 34-61-00-800-801. ACCOMPLISHED DFCS FMC LRU REPLACEMENT TEST, GROUP BITE 34, ALL TEST PASSED REF MM 22-11-00-740-806. THIS CLEARS MEL 34-36J.