Airworthiness DirectiveEASA AD US-2019-18-03

Exhaust - Thrust Reverser Upper Locking Actuators - Maintenance Instructions Amendment / Integrity Testing

Published: Sep 27, 2019
Effective: Oct 3, 2019
Deadline: Oct 3, 2019

Boeing 737

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

What to do

Affected operators must revise their maintenance or inspection programs to eliminate any procedures that allow modification of the thrust reverser upper locking actuator sensor target. For Boeing 737 NG series airplanes, operators must perform repetitive integrity tests of the thrust reverser upper locking actuator as specified. The AD became effective on October 3, 2019, and comments were invited until November 4, 2019.

Summary

The Exhaust - Thrust Reverser Upper Locking Actuators - Maintenance Instructions Amendment / Integrity Testing is a Federal Aviation Administration (FAA) airworthiness directive (AD 2019-18-03) applicable to all Boeing 737 series airplanes except models 737-100, -200, -200C, -300, -400, and -500. This directive addresses unsafe conditions related to the thrust reverser upper locking actuator by requiring revisions to maintenance programs and, for certain models, repetitive integrity testing. The AD aims to prevent undetected failures of the locking mechanism that could lead to in-flight thrust reverser deployment and loss of airplane control.

What changed

This new AD prohibits the practice of altering the thrust reverser upper locking actuator lock sensor target by removing or grinding material, which was previously allowed in some maintenance manuals. It mandates revising existing maintenance or inspection programs to remove such instructions and requires repetitive integrity tests of the thrust reverser upper locking actuator for Boeing 737-600, -700, -700C, -800, -900, and -900ER series airplanes. The AD does not require integrity testing for the newer 737 MAX models due to their limited operational wear.

Why it matters

This AD is critical for aviation professionals because it addresses a latent safety risk where improper maintenance procedures could mask a failed thrust reverser locking mechanism. For operators and maintenance organizations, compliance ensures that thrust reverser failures are detected promptly, reducing the risk of in-flight deployment that could cause loss of airplane control. It also requires updates to maintenance programs and additional testing, impacting maintenance planning and resource allocation.

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