# Proposed AD FAA-2017-0904: The Boeing Company Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2018-12-06
- Products: Boeing
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: October 6, 2017, 82 FR 46719
- Comments due: November 20, 2017
- Became: [AD 2018-12-06](https://openairdocs.org/ad/2018-12-06)
- Docket: FAA-2017-0904 (https://www.regulations.gov/docket/FAA-2017-0904, where comments are filed)
- FR document: 2017-21365
- Official PDF: https://openairdocs.org/files/sha256/2a/21/2a214b04bf7f316bf0049115c235e151c798371d3c26147bab9d2423620d81a5 (from https://www.govinfo.gov/content/pkg/FR-2017-10-06/pdf/2017-21365.pdf)
- Federal Register: https://www.federalregister.gov/documents/2017/10/06/2017-21365/airworthiness-directives-the-boeing-company-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9518A5F9342E5F8D862581B1004F99FE.0001
- Page: https://openairdocs.org/proposed/FAA-2017-0904

## Summary

We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 787-8 and 787-9 airplanes. This proposed AD was prompted by a report of an in-service reliability issue of a latent flow sensor failure combined with single cabin air compressor (CAC) operation. This condition resulted in reduced airflow which led to a persistent single CAC surge condition that caused overheat damage to the CAC inlet. This proposed AD would require installing new pack control unit (PCU) software for the cabin air conditioning and temperature control system (CACTCS) and new CAC outlet pressure sensor J-tube hardware, and doing related investigative and corrective actions if necessary. We are proposing this AD to address the unsafe condition on these products.

## Notices in this docket

- Oct 6, 2017: Notice of proposed rulemaking (NPRM). (first notice), FR document 2017-21365, comments due Nov 20, 2017 (https://www.federalregister.gov/documents/2017/10/06/2017-21365/airworthiness-directives-the-boeing-company-airplanes)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.