EASA AD US-2018-04-13
Engine Controls - Engine Electronic Control Unit (ECU) - Sealant Application
Summary
Federal Aviation Administration Airworthiness Directive 2018-04-13 is a final rule addressing certain Honeywell International Inc. AS907 series turbofan engines. It requires applying sealant to specific areas of the engine electronic control unit (ECU) to prevent water intrusion and inserting updated airplane operating procedures into flight manuals. This directive targets engines that have experienced loss-of-thrust-control events due to ECU water intrusion.
What Changed
This new airworthiness directive introduces mandatory sealant application to the ECU and updates flight manual procedures to mitigate seven reported loss-of-thrust-control events. It revises applicability criteria to focus on engine model, serial numbers, and ECU part numbers rather than Mod Record numbers. The directive removes interim action status and references to re-application of sealant, clarifying compliance requirements.
Why It Matters
This directive is critical for aviation professionals to prevent engine thrust control failures caused by water intrusion in the ECU, enhancing flight safety. Operators and maintenance teams must ensure affected engines are sealed properly and flight manuals are updated to comply with FAA regulations. Compliance reduces the risk of in-flight shutdowns and associated operational disruptions.
What To Do
Operators of aircraft with Honeywell AS907 series engines must apply sealant to the ECU as specified in Honeywell Service Bulletin AS907-76-9021, Revision 1, and update flight manuals with the prescribed operating procedures. Compliance must be completed by April 12, 2018. Maintenance personnel should verify ECU sealing status and follow the updated FAA requirements to maintain airworthiness.
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