What was found
DURING ANNUAL INSPECTION, PERFORMED WING SPAR INSPECTION PER AMERICAN CHAMPION SL 406 FOR WOOD SPARS: AC-43-16 ALERT NR 226 MAY97: FOUND EXTENSIVE COMPRESSION CRACKS AT FRONT, REAR AT BOTTOM OF BOTH WING SPARS. AIRCRAFT USED FOR AEROBATIC FLIGHT. AD 87-18-09 PREVIOUSLY C/W. NO ACCIDENT DAMAGE IN LOGS. AIRCRAFT ALWAYS HANGARED. EXTRA INSPECTION PANELS REQUIRED TO DISCOVER EXTENT OF CRACKING AND TO FACILITATE ACCESS.