EASA AD US-2025-21-02
Flight Controls - Non-Essential Gust Suppression Function - Disable
Summary
Flight Controls - Non-Essential Gust Suppression Function - Disable is a Federal Aviation Administration (FAA) Airworthiness Directive (AD 2025-21-02) that applies to all Boeing 777-200, -200LR, -300, -300ER, and 777F series airplanes. This AD addresses an unsafe condition related to high electrical resistance in gust suppression sensor transorb modules, which can expose actuator control electronics to damaging lightning voltages and potentially cause loss of airplane control.
What Changed
This AD supersedes AD 2022-15-06 by expanding the scope to include additional affected connectors and requires determining if affected transorb modules are installed, replacing or testing them, and performing on-condition actions. It also prohibits installation of affected parts and clarifies disconnect requirements for specific wire bundles and connectors.
Why It Matters
The directive is critical for aviation professionals because it mitigates the risk of flight control system malfunctions caused by electrical issues in the gust suppression system. Operators and maintenance teams must ensure compliance to prevent potential loss of airplane control due to erroneous flight control surface movements. The AD impacts fleet safety and maintenance planning for affected Boeing 777 models.
What To Do
Affected operators must comply with the AD by January 2, 2026, performing required disconnections, inspections, replacements, or tests of the gust suppression sensor transorb modules and connectors as specified. Installation of affected parts is prohibited from the effective date. Operators should review the AD docket and Boeing service information for detailed procedures and may request alternative methods of compliance if needed.