What was found
INSPECTIONS, HAVE FOUND SERIOUS EXFOLIATION CORROSION IN THE REAR SPAR FLANGES, NEAR THE ELEVATOR HINGE BRACKETS OF AT LEAST 2 AIRCRAFT. CORROSION HAD PROGRESSED TO THE EXTENT REQUIRING REMOVAL/REPLACEMENT OF THE SPAR FLANGES OR REPLACEMENT OF THE STABILIZER. RECOMMEND A MORE DETAILED INSPECTION OF THE SPAR FLANGES AND A CONSIDERABLE SHORTENING OF THE TIME BETWEEN INSPECTION REQUIREMENTS. THE CORROSION HAD PROGRESSED TO THE POINT OF COMPROMISING THE INTERIORITY OF THE SPAR AND ATTACHED ELEVATOR HINGE MOUNTING.