# Proposed AD FAA-2021-0543: The Boeing Company Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2021-25-09
- Products: Boeing
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: August 9, 2021, 86 FR 43454
- Comments due: September 23, 2021
- Became: [AD 2021-25-09](https://openairdocs.org/ad/2021-25-09)
- Docket: FAA-2021-0543 (https://www.regulations.gov/docket/FAA-2021-0543, where comments are filed)
- Project: AD-2021-00353-T
- FR document: 2021-16679
- Official PDF: https://openairdocs.org/files/sha256/36/51/365153e05e670948aaedcdcceefa0d445e4ce256cf37e2347d5d788e26a73bde (from https://www.govinfo.gov/content/pkg/FR-2021-08-09/pdf/2021-16679.pdf)
- Federal Register: https://www.federalregister.gov/documents/2021/08/09/2021-16679/airworthiness-directives-the-boeing-company-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/5FC7872B517EEB088625872D00797358.0001
- Page: https://openairdocs.org/proposed/FAA-2021-0543

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-200 and -200C series airplanes. This proposed AD was prompted by reports of nuisance stick shaker activation while the airplane was accelerating to cruise speed at the top of a climb. Investigation revealed the cause of the activation was the angle of attack (AOA) (also known as angle of airflow) sensor vanes had frozen and malfunctioned due to insufficient heat in certain AOA sensors to prevent ice buildup. This proposed AD would require inspecting the AOA sensors for certain part numbers or vane shapes, and replacing any affected AOA sensor with a new or serviceable sensor. The FAA is proposing this AD to address the unsafe condition on these products.

## Notices in this docket

- Aug 9, 2021: Notice of proposed rulemaking (NPRM). (first notice), FR document 2021-16679, comments due Sep 23, 2021 (https://www.federalregister.gov/documents/2021/08/09/2021-16679/airworthiness-directives-the-boeing-company-airplanes)

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