# Proposed AD FAA-2011-0571: The Boeing Company Model 747SP Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2012-03-09
- Products: Boeing
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: June 22, 2011, 76 FR 36390
- Comments due: August 8, 2011
- Became: [AD 2012-03-09](https://openairdocs.org/ad/2012-03-09)
- Docket: FAA-2011-0571 (https://www.regulations.gov/docket/FAA-2011-0571, where comments are filed)
- Project: 2010-NM-263-AD
- FR document: 2011-15536
- Official PDF: https://openairdocs.org/files/sha256/96/75/9675bb7e7f1632069dfc33c86a07501d8313612ee21c52832f2d772e991ce755 (from https://www.govinfo.gov/content/pkg/FR-2011-06-22/pdf/2011-15536.pdf)
- Federal Register: https://www.federalregister.gov/documents/2011/06/22/2011-15536/airworthiness-directives-the-boeing-company-model-747sp-series-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DD7112F346BC5A47862578B7004DCF5E.0001
- Page: https://openairdocs.org/proposed/FAA-2011-0571

## Summary

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require replacing or modifying the upper and lower rudder power control modules (PCM). This proposed AD was prompted by a report of a rudder hard-over event on a Model 747-400 series airplane, caused by a rudder PCM manifold cracking and separating in the area of the yaw damper cavity end-cap. We are proposing this AD to prevent a failure of the lower or upper rudder PCM manifold, which could result in a hard-over of the rudder surface leading to an increase in pilot workload and a possible high-speed runway excursion upon landing.

## Notices in this docket

- Jun 22, 2011: Notice of proposed rulemaking (NPRM). (first notice), FR document 2011-15536, comments due Aug 8, 2011 (https://www.federalregister.gov/documents/2011/06/22/2011-15536/airworthiness-directives-the-boeing-company-model-747sp-series-airplanes)

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