EASA SIB 2008-41
Eurocopter EC155, SA365N, AS365N, SA366G1, SA360C and SA365C series helicopters - MGB Casing Corrosion
Summary
EASA Safety Information Bulletin 2008-41 is an informational bulletin addressing corrosion issues in the Main Gearbox (MGB) casing of Eurocopter EC155, SA365N, AS365N, SA366G1, SA360C, and SA365C series helicopters. It references the French DGAC Emergency Airworthiness Directive UF-2008-004, which mandates inspection and repair of the MGB casing if corrosion is found. The bulletin applies to all serial numbers of these helicopter models equipped with MGBs delivered or overhauled before specified dates.
What Changed
This bulletin introduces mandatory inspections of the MGB casing lower area for corrosion where PR sealing compound was applied due to a production error. It requires operators to check for corrosion and apply repairs if necessary, based on detailed procedures in referenced Eurocopter Alert Service Bulletins. The bulletin clarifies that EASA does not have authority to issue an AD on this issue as it is a manufacturing non-conformity, so national authorities must enforce the directive.
Why It Matters
This issue is critical because corrosion in the MGB casing can lead to structural weakening, crack initiation, and potential failure, risking loss of helicopter control. Operators and maintenance organizations must address this to ensure flight safety and regulatory compliance. Timely inspections and repairs help prevent accidents and maintain airworthiness of affected Eurocopter helicopters.
What To Do
Operators must inspect the MGB casing within 15 flight hours for the presence of PR sealing compound and corrosion following the referenced Eurocopter Alert Service Bulletins. If corrosion is found, repairs must be applied before further flight. Subsequent inspections are required at specified intervals depending on operational conditions and MGB age. Spare MGBs must also be inspected before installation.
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