Airworthiness DirectiveEASA AD US-2018-26-05

Fuel - Motor-Operated Valve Actuators / Maintenance or Inspection Program - Inspection / Replacement / Revision

Published: Jan 11, 2019
Effective: Feb 1, 2019
Deadline: Feb 1, 2019

Boeing 777

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What to do

Operators of affected Boeing Model 777 airplanes must inspect the MOV actuators at engine fuel shutoff spar valve positions to verify part numbers or confirm software versions. If necessary, they must replace actuators with approved parts or install updated AIMS software. Additionally, maintenance programs must be revised to incorporate the new airworthiness limitation by the effective date of February 1, 2019.

Summary

The Federal Aviation Administration's Airworthiness Directive 2018-26-05 addresses certain Boeing Model 777 airplanes. It requires inspection and possible replacement of motor-operated valve (MOV) actuators at the engine fuel shutoff spar valve positions and mandates revising the maintenance or inspection program to include a new airworthiness limitation. This directive aims to prevent latent failures of engine fuel shutoff spar valves that could compromise fuel flow termination during emergencies.

What changed

This new airworthiness directive introduces mandatory inspections to verify the part numbers of MOV actuators installed at engine fuel shutoff spar valve positions, requires installing MOV actuators with approved part numbers or updated software versions, and adds a new airworthiness limitation to maintenance programs. It also clarifies compliance options based on installed software versions and addresses previous public comments to refine inspection and replacement procedures.

Why it matters

This directive is critical for aviation professionals because latent failures of engine fuel shutoff spar valves can prevent fuel flow termination, increasing the risk of engine fires and potential wing failure. Operators and maintenance organizations must ensure compliance to maintain aircraft safety and regulatory adherence. The added airworthiness limitation helps prevent reinstallation of unsafe MOV actuators, reducing the risk of future failures.

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