What was found
FUSELAGE SKIN CRACKED JUST AFT OF FRAME 75 & ABOVE STRINGER 2L. CRACK IS APPROX 3/8" IN LENGTH, EASI 8071 USED. FREQ=400KHZ, LPF=100, V-GAIN=76.0, H-GAIN=65.0, 50-500KHZ PROBE. PERFORMED PERMANENT REPAIR OF LT REAR FUSELAGE I SKIN JUST AFT OF FRAME 75 ABOVE STRINGER 2L IAW ERS-EM-53MR-1309.