What was found
FLT#688, BNA-LGA. (AIRCRAFT DIVERTED TO JFK AND DECLARED AN EMERGENCY) ' FLAP FAIL EICAS MSG AT 4000FT SPD 210 SLAT 3/ FLAP 0 WITH FLAP HANDLE SET TO 1 VSI -400 AT TOUCHDOWN; PERFORMED WHEEL OVERSPEED INSPECTION/ CHECK FOR ANY ABNORMALITIES/DAMAGE NONE NOTED AMM 05-50-22. T/S FLAP FAIL EICAS MSG" NOTED COROLATED FAULT CODE 27532018 ACE A250 CODE 27512014ACE" FLAP SURFACE SAMMED/OVERSPEED. FLAPS ACE1 LATCHED FAULT. FOLLOWED FIM 27-51-00 CONCLUDED AT STEP 3/SUBTASKS. NOTED STRONG GEAR GRINDING NOISE COMING FROM FLAP PDU" FLAP REQUIRES REPLACEMENT. REMOVED AND REPLACED FLAP POWER DRIVE UNIT IAW AMM 27-51-05. REQUIRES COTTER PIN AND SAFETY WIRE OF BOLTS. REQUIRES OPS CHECK REF LP 3701559, ITEM 1. INSTALLED COTTER PIN AND SAFETY WIRE BOLTS IAW AMM 27-51-05 REQUIRES OPS CHK AND ELECTRONIC RIGGING REF LP 3701560, ITEM 2 (ACCOMPLISHED OPS CHECK OF FLAP POWER DRIVE UNIT PER AMM 27-50-00-710-801, ALOS ACCOMPLISHED FLAP CONTROL SYS ELECTRICAL RIGGING PER AMM 27-50-00-820.).'