EASA AD US-2021-25-09
Flight Controls - Angle of Attack Sensor - Inspection /Replacement
Summary
Federal Register Volume 86, Number 246, Final Rule titled 'Flight Controls - Angle of Attack Sensor - Inspection /Replacement' is an FAA Airworthiness Directive (AD 2021-25-09) applicable to Boeing 737-200 and -200C series airplanes. It addresses issues with angle of attack (AOA) sensors that may freeze due to insufficient heating, causing nuisance stick shaker activation during climb acceleration.
What Changed
This new AD requires inspection of AOA sensors for specific part numbers or vane shapes and mandates replacement of any affected sensors with new or serviceable units. It introduces mandatory compliance actions to prevent AOA sensor vane freezing and malfunction on the specified Boeing 737 models.
Why It Matters
This AD is critical for aviation professionals because frozen AOA sensor vanes can transmit inaccurate data, potentially leading to loss of airplane control. Operators and maintenance teams must ensure compliance to maintain flight safety and prevent in-flight incidents related to unreliable angle of attack information.
What To Do
Operators of Boeing 737-200 and -200C airplanes must inspect the AOA sensors within 120 days of the AD's effective date for Group 2 airplanes, and comply with all required actions as specified in Boeing Alert Service Bulletin 737-27A1324 for Group 1 airplanes. Any affected sensors must be replaced promptly to meet the AD requirements.
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