Airworthiness DirectiveEASA AD US-2020-24-02

NOT ADOPTED - EASA DECISION ATTACHED

Published: Nov 20, 2020
Effective: Nov 20, 2020
Deadline: Nov 20, 2020
Replaces: 2018-23-51

Boeing 737 8 9

AI-generated summary of the official EASA document. Verify against the PDF before acting.

What to do

Affected operators must install the new flight control and display system software, revise the Airplane Flight Manual with updated procedures, modify horizontal stabilizer trim wiring, conduct angle of attack sensor system tests, and complete operational readiness flights before returning aircraft to service. Operators must also update their FAA-approved minimum equipment lists to incorporate more restrictive provisions for dispatch with certain inoperative systems. The effective date for compliance is November 20, 2020.

Summary

The Federal Aviation Administration's final rule titled Airworthiness Directive 2020-24-02 supersedes AD 2018-23-51 and applies to Boeing 737-8 and 737-9 (737 MAX) airplanes. It mandates software updates to the flight control computer and MAX display system, revisions to the Airplane Flight Manual, wiring modifications, angle of attack sensor system tests, and operational readiness flights. This directive addresses unsafe conditions related to erroneous angle of attack sensor inputs that could cause repeated nose-down horizontal stabilizer trim.

What changed

This directive replaces the previous AD 2018-23-51 by requiring installation of new flight control computer software that uses inputs from both angle of attack sensors to prevent repeated MCAS activation. It also mandates updated flightcrew procedures, new MAX display system software with an AOA DISAGREE alert, wiring separation changes, and operational tests before returning aircraft to service. Additionally, it narrows the applicability to certain 737 MAX airplanes and imposes more restrictive minimum equipment list provisions for dispatch with inoperative systems.

Why it matters

This AD is critical for aviation professionals as it enhances flight safety by mitigating risks associated with erroneous angle of attack sensor data that previously contributed to unsafe flight conditions. Operators and maintenance teams must ensure compliance with updated software and procedural requirements to maintain airworthiness and regulatory approval. The directive also impacts pilot training and operational readiness, requiring coordination between operators, MROs, and regulatory authorities.

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