- Effective
- October 2, 2008
- Published
- August 28, 2008 · 73 FR 50714–50716
- Issued
- August 12, 2008
- Models
- 737-600 Series, 737-700 Series, 737-800 Series, 737-900 Series
- Data sheet
- TCDSA16WE
- Registered aircraft
- 783 matched by model
- Product
- Aircraft · Large airplane
- Amendment
- 39-15653
- Docket
- FAA-2008-0621
- Project
- 2008-NM-015-AD
- Issued as
- Final rule
Unofficial copy from the Federal Register XML, document E8-19367. Only the govinfo PDF is the legal edition. DRS record last changed August 7, 2025.
Copies of the files this page was built from, with their SHA-256. Retrieved October 18, 2026.
| File | Size | SHA-256 | Original |
|---|---|---|---|
| Official PDF | 155 KB | 4899cfcc…714db73 | E8-19367.pdf on govinfo.gov |
| Federal Register XML | 18 KB | 9746ee11…c483fa5 | E8-19367.xml on federalregister.gov |
| FAA DRS HTML attachment | 55 KB | 75e910a1…986640a | FAA DRS (API key needed) |
| FAA DRS PDF | 27 KB | b8ac7495…2d3687d | FAA DRS (API key needed) |
On this page
Summary
We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -800, and -900 series airplanes. This AD requires installing hot short protector (HSP) support brackets and equipment for the fuel quantity indicating system (FQIS) fuel densitometer and other specified actions as applicable. This AD also requires revising the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness to incorporate AWL No. 28-AWL-07. This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent the center tank fuel densitometer from overheating and becoming a potential ignition source inside the center fuel tank, which, in combination with flammable fuel vapors, could result in a center fuel tank explosion and consequent loss of the airplane.
The airworthiness directive
2008-17-15 Boeing: Amendment 39-15653. Docket No. FAA-2008-0621; Directorate Identifier 2008-NM-015-AD.
(a) Effective Date
PDF page 2(a) This airworthiness directive (AD) is effective October 2, 2008.
(b) Affected ADs
PDF page 2(b) None.
(c) Applicability
PDF page 2(c) This AD applies to Boeing Model 737-600, -700, -800, and -900 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 737-28A1221, Revision 1, dated November 9, 2007.
Note 1:
This AD requires revisions to certain operator maintenance documents to include new inspections. Compliance with these inspections is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these inspections, the operator may not be able to accomplish the inspections described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance (AMOC) according to paragraph (k) of this AD. The request should include a description of changes to the required inspections that will ensure the continued operational safety of the airplane.
(d) Unsafe Condition
PDF page 2(d) This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent the center tank fuel densitometer from overheating and becoming a potential ignition source inside the center fuel tank, which, in combination with flammable fuel vapors, could result in a center fuel tank explosion and consequent loss of the airplane.
(e) Compliance
PDF page 2(e) Comply with this AD within the compliance times specified, unless already done.
(f) Installation of the Hot Short Protector (HSP)
PDF page 2(f) Within 60 months after the effective date of this AD, install the HSP support brackets and equipment for the fuel quantity indicating system (FQIS) fuel densitometer and do all the other specified actions as applicable, by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-28A1221, Revision 1, dated November 9, 2007.
(g) Airworthiness Limitations (AWLs) Revision for AWL No. 28-AWL-07
PDF page 2(g) Concurrently with accomplishing the actions required by paragraph (f) of this AD, revise the AWLs section of the Instructions for Continued Airworthiness (ICA) by incorporating AWL No. 28-AWL-07 of Subsection F, “AIRWORTHINESS LIMITATIONS—FUEL SYSTEM AWLs,” of Section 9 of the Boeing 737-600/700/800/900 Maintenance Planning Data (MPD) Document, D626A001-CMR, Revision March 2007 R2 (hereafter referred to as “the MPD”).
(h) No Alternative Critical Design Configuration Control Limitations (CDCCLs)
PDF page 2(h) After accomplishing the action specified in paragraph (g) of this AD, no alternative CDCCLs may be used unless the CDCCLs are approved as an alternative methods of compliance (AMOC) in accordance with the procedures specified in paragraph (k) of this AD.
(i) Credit for Actions Done According to Previous Issue of Service Bulletin
PDF page 2(i) Actions done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 737-28A1221, dated January 14, 2007, are acceptable for compliance with the requirements of paragraph (f) of this AD.
(j) Terminating Action for AWLs Revision
PDF page 3(j) Incorporating AWL No. 28-AWL-07 into the AWLs section of the ICA in accordance with paragraph (g)(3) of AD 2008-10-10, amendment 39-15516, terminates the action required by paragraph (g) of this AD.
(k) AMOCs
PDF page 3(k)(1) The Manager, Seattle Aircraft Certification Office, FAA, ATTN: Georgios Roussos, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone (425) 917-6482; fax (425) 917-6590; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.
(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.
(l) Material Incorporated by Reference
PDF page 3(l) You must use Boeing Alert Service Bulletin 737-28A1221, Revision 1, dated November 9, 2007; and Airworthiness Limitation 28-AWL-07 of Section 9 of the Boeing 737-600/700/800/900 Maintenance Planning Data (MPD) Document, D626A001-CMR, Revision March 2007 R2; to do the actions required by this AD, unless the AD specifies otherwise.
(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.
(3) You may review copies of the service information incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
Rule preamble
The FAA’s background, reasoning and cost estimate, published with the AD.
DatesPage 1
This AD is effective October 2, 2008.
The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of October 2, 2008.
AddressesPage 1
For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.
For further information contactPage 1
Georgios Roussos, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6482; fax (425) 917-6590.
DiscussionPage 1
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Boeing Model 737-600, -700, -800, and -900 series airplanes. That NPRM was published in the Federal Register on June 9, 2008 (73 FR 32491). That NPRM proposed to require installing hot short protector (HSP) support brackets and equipment for the fuel quantity indicating system (FQIS) fuel densitometer and other specified actions as applicable. That NPRM proposed to also require revising the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness to incorporate AWL No. 28-AWL-07.
CommentsPage 1
We gave the public the opportunity to participate in developing this AD. We considered the single comment received. Boeing concurs with the NPRM.
Change to Final Rule Regarding Later Revisions of Service InformationPage 1
We removed all references to the use of “later revisions” of the applicable service information from this AD to be consistent with FAA and Office of the Federal Register policies. We may consider approving the use of later revisions of the service information as an alternative method of compliance with this AD, as provided by paragraph (k) of this AD.
ConclusionPage 1
We reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting the AD with the change described previously. We also determined that this change will not increase the economic burden on any operator or increase the scope of the AD.
Costs of CompliancePage 2
We estimate that this AD affects 13 airplanes of U.S. registry. The following table provides the estimated costs, at an average labor rate of $80 per work hour, for U.S. operators to comply with this AD.
| Action | Work hours | Parts | Cost per airplane | Number of U.S.-registered airplanes | Fleet cost |
|---|---|---|---|---|---|
| Installation of HSP support brackets and equipment | Up to 16 | Up to $14,698 | Up to $15,978 | 13 | Up to $207,714 |
| AWLs revision | 1 | None | $80 | 13 | $1,040 |
Authority for This RulemakingPage 2
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
Regulatory findingsPage 2
This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a “significant regulatory action” under Executive Order 12866,
(2) Is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), and
(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.
Adoption of the amendmentPage 2
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
2. The FAA amends § 39.13 by adding the following new AD:
Affected TCDS · 1
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 783
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1998 | 38 |
|---|---|
| 1999 | 86 |
| 2000 | 72 |
| 2001 | 83 |
| 2002 | 12 |
| 2003 | 7 |
| 2004 | 13 |
| 2005 | 14 |
| 2006 | 21 |
| 2007 | 21 |
| 2008 | 26 |
| 2009 | 38 |
| 2010 | 62 |
| 2011 | 21 |
| 2012 | 30 |
| 2013 | 31 |
| 2014 | 23 |
| 2015 | 20 |
| 2016 | 42 |
| 2017 | 72 |
| 2018 | 27 |
| 2025 | 2 |
22 with no year recorded