What was found
FLAP FAIL ON ARRIVAL, 37 DEGREES, 1800 FEET, SPEED ROUGHLY 155 - 160. R & R LT BPSU IAW AMM 27-51-10, NO FIX. R & R LT NR 1 & 2 FLEX SHAFTS, FLAP IAW AMM 27-53-10. DUE TO DAMAGE, CLEANED NR 3 & 4 FLEX SHAFTS IAW AMM 27-53-10. R & R FLAP PDU IAW AMM 27-52-01. COMPLETED RIG OF BPSU IAW AMM 27-51-10. OPERATIONS TESTED OK, NO FURTHER DEFECTS NOTED IAW AMM 27-51-00.