EASA AD US-2018-19-32
Nacelles / Pylons - Nacelle Strut Spar, Overwing Fittings and Diagonal Braces / Fittings - Inspection / Replacement
Summary
Federal Aviation Administration Airworthiness Directive 2018-19-32 is a final rule applicable to all Boeing Model 707, 720, and 720B series airplanes. It addresses safety concerns related to fractures in the midspar fitting of nacelle strut spars, which could lead to engine separation. The directive mandates repetitive inspections and replacement of certain nacelle strut spar, overwing fittings, diagonal braces, and associated components to ensure structural integrity.
What Changed
This new airworthiness directive introduces mandatory repetitive detailed and high frequency eddy current inspections of nacelle strut spar fittings, overwing fittings, and diagonal braces. It also requires replacement of the diagonal brace assembly on certain airplanes where attach holes have been oversized as specified in Boeing 707 Alert Service Bulletin A3364 Revision 3. The directive updates inspection criteria to improve detection of cracks that previous inspections failed to identify timely.
Why It Matters
This directive is critical for aviation professionals because undetected cracks in nacelle strut fittings can grow and cause structural failure, potentially resulting in engine separation from the aircraft. Operators, maintenance, and compliance teams must ensure adherence to the inspection and replacement requirements to maintain airworthiness and prevent catastrophic failures. The directive enhances safety by addressing a previously insufficient inspection regime.
What To Do
Operators of Boeing 707, 720, and 720B series airplanes must perform repetitive detailed and high frequency eddy current inspections of specified nacelle strut spar, overwing fittings, and diagonal braces as outlined in Boeing Alert Service Bulletins A3364 Revision 4, A3365 Revision 3, and A3514 Revision 1. Replacement of diagonal brace assemblies with oversized attach holes per Boeing Alert Service Bulletin A3364 Revision 3 is required. Compliance with these actions is mandatory by November 2, 2018.
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