# Proposed AD FAA-2007-28661: The Boeing Company Model 737-600, -700, -700C, -800, and -900 Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2011-18-03
- Products: Boeing
- Product type: Aircraft
- Action: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
- Published: March 8, 2011, 76 FR 12634
- Comments due: April 4, 2011
- Became: [AD 2011-18-03](https://openairdocs.org/ad/2011-18-03)
- Docket: FAA-2007-28661 (https://www.regulations.gov/docket/FAA-2007-28661, where comments are filed)
- Project: 2007-NM-013-AD
- FR document: 2011-5156
- Official PDF: https://openairdocs.org/files/sha256/9f/19/9f197ccfdb8300c780413d48f2b7d15c56eb292c8e8ca7e0274fdcb818c352a6 (from https://www.govinfo.gov/content/pkg/FR-2011-03-08/pdf/2011-5156.pdf)
- Federal Register: https://www.federalregister.gov/documents/2011/03/08/2011-5156/airworthiness-directives-the-boeing-company-model-737-600--700--700c--800-and--900-series-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/A26E3BA3D8CEA2878625784D0056054B.0001
- Page: https://openairdocs.org/proposed/FAA-2007-28661

## Summary

We are revising an earlier proposed airworthiness directive (AD) for the products listed above. That NPRM proposed to require installation of an automatic shutoff system for the center tank fuel boost pumps, installation of a placard in the airplane flight deck if necessary, and concurrent modification of the P5-2 fuel control module assembly. That NPRM also proposed to require revisions to the Limitations and Normal Procedures sections of the airplane flight manual to advise the flightcrew of certain operating restrictions for airplanes equipped with an automated center tank fuel pump shutoff control. Additionally, that NPRM proposed to require a revision to the Airworthiness Limitations (AWL) section of the Instructions for Continued Airworthiness (ICA) to incorporate AWL No. 28-AWL-19 and No. 28-AWL-23. That NPRM further proposed to require installation of a secondary control relay for the electrical control circuit of each of the two center tank fuel boost pumps. That NPRMwas prompted by fuel system reviews conducted by the manufacturer. This action revises that NPRM by adding airplanes, adding additional operational testing of the automatic shutoff system for certain airplanes, removing the requirement for incorporating AWL No. 28-AWL-19 into the AWL section of the ICA, and adding an option of installation and maintenance of universal fault interrupters using a certain supplemental type certificate. We are proposing this supplemental NPRM to prevent center tank fuel pump operation with continuous low pressure, which could lead to friction sparks or overheating in the fuel pump inlet that could create a potential ignition source inside the center fuel tank. These conditions, in combination with flammable fuel vapors, could result in a center fuel tank explosion and consequent loss of the airplane. Since these actions impose an additional burden over those proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.

## Notices in this docket

- Jul 10, 2007: Notice of proposed rulemaking (NPRM). (first notice), FR document E7-13326, comments due Aug 24, 2007 (https://www.federalregister.gov/documents/2007/07/10/E7-13326/airworthiness-directives-boeing-model-737-600--700--700c--800-and--900-series-airplanes)
- Mar 8, 2011: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period., FR document 2011-5156, comments due Apr 4, 2011 (https://www.federalregister.gov/documents/2011/03/08/2011-5156/airworthiness-directives-the-boeing-company-model-737-600--700--700c--800-and--900-series-airplanes)

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