EASA SIB CE-11-41
Air Tractor, Inc. AT-300, AT-400 and AT-500 Series - Fuselage-to-Wing Attachment Fittings
Summary
The Air Tractor, Inc. AT-300, AT-400 and AT-500 Series - Fuselage-to-Wing Attachment Fittings Special Airworthiness Information Bulletin (SAIB: CE-11-41) informs owners and operators of Air Tractor AT-300, AT-400, and AT-500 series aircraft about potential fatigue cracking in the fuselage frame wing attach tubes. This bulletin covers models including AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-401A, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, AT-503, AT-503A, and AT-504. It provides inspection guidance but does not mandate regulatory action.
What Changed
This SAIB introduces recommendations for recurring visual inspections of the fuselage wing attach tubes and wing attach angles to detect fatigue cracks. It references Snow Engineering Co. Service Letter #296, which specifies inspection intervals and procedures, including borescope inspections every 100 hours and detailed inspections annually with parts removed. The bulletin also highlights previous service letters addressing related cracking issues and repair methods.
Why It Matters
Fatigue cracks in the fuselage wing attach tubes and wing attach angles can compromise the structural integrity of the wing-to-fuselage connection, potentially leading to failure. For operators and maintenance organizations, early detection through recommended inspections is critical to maintaining airworthiness and preventing costly repairs or unsafe conditions. Compliance teams benefit from clear guidance on inspection intervals and repair protocols to ensure continued safe operation of affected Air Tractor aircraft.
What To Do
Operators of affected Air Tractor AT-300, AT-400, and AT-500 series aircraft should perform visual inspections of the fuselage wing attach tubes and wing attach angles as directed in Snow Engineering Co. Service Letter #296. Inspections should occur every 100 flight hours using a borescope, with more thorough inspections annually. Any cracks found must be confirmed with dye penetrant inspection after paint removal, and repairs should be coordinated with the Air Tractor Service Department. No mandatory compliance deadline is specified.