EASA AD US-2020-06-14
Integrated Modular Avionics - Electrical Power - Repetitive Cycling
Summary
The Federal Aviation Administration's Airworthiness Directive 2020-06-14 addresses all Boeing 787-8, 787-9, and 787-10 airplanes. It mandates repetitive cycling of the airplane electrical power to prevent loss of the stale-data monitoring function in the common core system (CCS), which can occur after 51 days of continuous power. This directive aims to mitigate risks of undetected failures in the common data network (CDN) that could lead to erroneous flight-critical data displays.
What Changed
This new airworthiness directive introduces a requirement for repetitive electrical power cycling on Boeing 787 models to prevent the loss of CCS stale-data monitoring. It was prompted by reports of potential failures in the CDN message age validation after extended continuous power, which could cause misleading flight data without annunciation. The directive is an interim action and may be subject to further rulemaking.
Why It Matters
This directive is critical for aviation professionals because it addresses a safety risk that could lead to misleading flight data such as incorrect attitude, altitude, airspeed, and engine indications. Operators and maintenance teams must ensure compliance to maintain the integrity of flight-critical systems and avoid potential catastrophic failures. Compliance helps preserve safe flight operations and protects flightcrew situational awareness.
What To Do
Operators of Boeing 787-8, 787-9, and 787-10 airplanes must perform repetitive cycling of the airplane electrical power as specified in Boeing Alert Service Bulletin B787-81205-SB420045-00, Issue 002. This action must be implemented by April 7, 2020, the effective date of the directive. Stakeholders should also submit any comments on the directive by May 7, 2020, as invited by the FAA.
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