What was found
UPON TAKEOFF DURING GEAR RETRACTION FIRST THROTTLE REDUCTION AND THE FINAL TRAVEL OF FLAPS LOAD BANG HEARD. IT WAS PRECEDED BY BY TWO LOUD THUMPS THEN A VERY LOUD BANG. EVERYTHING FUCNTIONED NORMALLY AFTER. UPON LANDING NO OBVIOUS PROBLEMS OBSERVED IN THE GEAR OR FLIGHT CONTROLS I CANNOT SAY FOR SURE WHAT CAUSED IT. NOTE IT DID HAPPEN RETARDING THE THROTTLES OUT OF THE TAKEOFF POSITION DID NOT LAND OVERWEIGHT. REMOVED LH HMU REPLACEMENT HMU PERFORMED OPERATIONAL CHECK IAW AMM 73-20-01 OPERATIONAL TEST SATISFACTORY REMOVED RH HMU. INSTALLED RH HMU IAW AMM 73-20-01 OPERATIONAL TEST REQUIRED PERFORMED OPERATIONAL CHECK IAW AMM 73-20-01 OPERATIONAL TEST SATISFACTORY.