Airworthiness DirectiveEASA AD US-2017-25-10

Stabilizers - Elevator Hinges - Inspections / Replacement

Published: Jan 18, 2018
Effective: Jan 18, 2018
Deadline: Jan 18, 2018

Boeing 737 100 200 200C 300 400

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

What to do

Operators of affected Boeing 737 models must perform the required repetitive inspections, checks, replacements, and tests of elevator hinges and bearing plates as specified in the directive and Boeing Alert Service Bulletin 737-55A1099, Revision 1. Compliance with the directive is mandatory starting January 18, 2018. Any necessary investigative and corrective actions identified during inspections must be completed promptly to maintain airworthiness.

Summary

Federal Aviation Administration Airworthiness Directive 2017-25-10 is a final rule addressing all Boeing 737-100, -200, -200C, -300, -400, and -500 series airplanes. It mandates repetitive inspections, replacements, and tests of elevator hinge components and bearing plates to prevent potential disconnection of elevator hinges that could lead to horizontal stabilizer structural degradation. This directive aims to ensure continued airworthiness and safe flight by mitigating risks associated with bearing plate slider bushing wear.

What changed

This new airworthiness directive introduces mandatory repetitive inspections and checks of elevator hinges number 4 and 6, along with related components, as well as repetitive replacements and tests of the bearing plate. It removes a previously proposed reference to Boeing Alert Service Bulletin 737-55A1099 for Group 1 airplanes and clarifies that only specific hinges require inspection based on flutter analysis. The directive also confirms that installation of Supplemental Type Certificate ST01219SE does not affect compliance requirements.

Why it matters

This directive is critical for operators and maintenance organizations as it addresses a safety risk that could cause heavy airplane vibration, structural damage, and potential loss of elevator or horizontal stabilizer. Compliance ensures early detection and correction of wear-related issues, preventing in-flight failures and maintaining aircraft structural integrity. It also provides clear guidance on inspection scope and methods, helping maintenance teams prioritize resources effectively.

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