What was found
CRACKS DEVELOPED IN THE FRAME ALONG THE BOTTOM WHERE IT ATTACHES TO THE TAIL CONE SKIN. THE CRACKS TYPICALLY ORIGINATE FROM THE RIVETS AND RUN ALONG THE RIVET LINE. SOME CRACKS RUN BETWEEN RIVETS BUT DID NOT INTERSECT. OTHER CRACKS WENT TO THE EDGE. ONE CLIP ON THE RIGHT HAND LOWER POSITION WAS CRACKED IN THE SAME MANNER. THE RIGHT HAND REINFORCING ANGLE P/N 117-22122-001.02 ALSO HAD A CRACK IN THE BEND RADIUS. CRACKED ALSO DEVELOPED UNDER THE UPPER AFT ECU MOUNT. THE CRACKS WEREBETWEEN AND AROUND RIVETS THAT HOLD THE MOUNT TO THE TAIL CONE SKIN. THE CRACKS ARE IN THE SKIN. INSTALLED REINFORCING ANGLE ALONG THE BOTTOM OF THE FRAME ACCORDING TO SB BK117-20-101 AND ALSO REPLACED THE CLIP.