What was found
WEB BULKHEAD AT STA 272 REAR AFT FUSELAGE, FOUND CRACKS AT TOP PORTION ON RADIUS OF POST. CRACK TO BE APPROX 1 INCH ON LT AND ABOUT .2400 INCH ON RT, ALSO CAUSING DOUBLER TO CRACK OUT THAT HOLDS THE 2 SKINS TOGETHER. PROBABLE CAUSE, JUST HIGH TIME IN AIRFRAME, ALSO MFG TO MAKE A MODIFICATION, SUCH AS A BIGGER DOUBLER TO PREVENT FUTURE CRACKS. (K)