EASA AD US-2018-23-51: Superseded by FAA AD 2020-24-02

What to do

Operators of Boeing 737-8 and 737-9 airplanes must revise the certificate limitations and operating procedures sections of the airplane flight manual within 3 days of the AD's effective date, December 21, 2018. They should incorporate the specified runaway horizontal stabilizer trim procedures and ensure flight crews are trained accordingly. Comments on the AD can be submitted by January 22, 2019.

Summary

FAA Airworthiness Directive 2018-23-51 is a final rule affecting all Boeing 737-8 and 737-9 airplanes. It requires revising the airplane flight manual to include procedures for flight crews to handle runaway horizontal stabilizer trim caused by erroneous high angle of attack sensor inputs. This directive addresses a safety risk identified by the manufacturer that could lead to loss of control and potential terrain impact.

What changed

This directive introduces a mandatory revision to the certificate limitations and operating procedures chapters of the airplane flight manual. It provides specific runaway horizontal stabilizer trim procedures for flight crews to follow under certain conditions triggered by faulty angle of attack sensor data. The AD is an interim safety action pending further rulemaking.

Why it matters

This AD is critical for aviation professionals because it mitigates a potentially dangerous flight control issue that can cause repeated nose-down trim commands, making the airplane difficult to control. Operators and maintenance teams must ensure compliance to prevent excessive nose-down attitudes and altitude loss, thereby enhancing flight safety. Compliance also ensures adherence to FAA regulatory requirements and avoids operational disruptions.

What to do

Summary

What changed

Why it matters

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