EASA AD US-2023-04-17
Fuel - Auxiliary Power Unit Fuel Line Shroud / Pressure Switch Wire Clamp - Inspection
Summary
The Federal Aviation Administration's Airworthiness Directive 2023-04-17 is a final rule addressing certain Boeing 737-8, 737-9, and 737-600, -700, -700C, -800, -900, and -900ER series airplanes. It mandates inspections of the auxiliary power unit (APU) fuel line shroud and the pressure switch wire clamp assembly to detect damage and incorrect fastener installation that could cause interference and potential fuel leaks. This directive aims to prevent flammable fluid leaks in ignition zones due to damaged APU fuel line shrouds.
What Changed
This new airworthiness directive introduces mandatory inspections of the APU fuel line shroud for damage and the pressure switch wire clamp for proper bolt orientation and spacing. It requires corrective actions if damage or incorrect installation is found. The AD does not currently allow on-wing repairs or incorporate pending revisions to Boeing service bulletins.
Why It Matters
This directive is critical for operators and maintenance organizations to prevent potential fuel leaks that could lead to fire hazards. Compliance ensures the structural integrity of the APU fuel system and reduces the risk of ignition in critical aircraft zones. It also impacts maintenance planning due to the inspection and possible replacement workload.
What To Do
Operators must inspect the APU fuel line shroud and pressure switch wire clamp according to Boeing Alert Requirements Bulletins by May 1, 2023. If damage or incorrect fastener installation is found, they must perform on-condition corrective actions, including clamp reinstallation or shroud replacement. Parts availability and adherence to the specified procedures are essential for compliance.
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