ACTION: Final rule.

SUMMARY: We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. This AD requires a one-time inspection to determine the material of the forward and aft gray water drain masts. For airplanes having composite gray water drain masts, this AD requires installation of a bonding jumper between a ground and the clamp on the tube of the forward and aft gray water composite drain masts. This AD results from a report of charred insulation blankets and burned wires around the forward gray water composite drain mast found during an inspection of the forward cargo compartment on a Model 767-300F airplane. We are issuing this AD to prevent a fire near a composite drain mast and possible disruption of the electrical power system caused by a lightning strike on a composite drain mast, which could result in the loss of several functions essential for safe flight. 

DATES: This AD is effective May 27, 2008. 
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of May 27, 2008. 

ADDRESSES: For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124- 2207. 

Examining the AD Docket 

You may examine the AD docket on the Internet at http:// www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (telephone 800-647-5527) is the Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590. 

FOR FURTHER INFORMATION CONTACT: Nicholas Wilson, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6476; fax (425) 917-6590. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed rulemaking (NPRM) (the "original NPRM'') to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. That NPRM was published in the Federal Register on September 6, 2007 (72 FR 51201). That NPRM proposed to require a one-time inspection to determine the material of the forward and aft gray water drain masts. For airplanes having composite gray water drain masts, that NPRM also proposed to require installation of a bonding jumper between a ground and the clamp on the tube of the forward and aft gray water composite drain masts. 

Actions Since NPRM Was Issued 

Since we issued the NPRM, Boeing has issued new service information that includes corrected measurement values and procedures that should be followed if the resistance of the bonding jumper exceeds certain values during the initial resistance check. 
We have reviewed Boeing Special Attention Service Bulletin 737-30- 1056, Revision 1, dated October 25, 2007. The service bulletin describes procedures for installing a bonding jumper between a ground and the clamp on the tube of the forward and aft gray water composite drain mast. We have revised this final rule to refer to Revision 1 of the service bulletin as the appropriate source of service information for the required actions. We have also added paragraph (h) to this final rule to give credit for actions done previously in accordance with Boeing Special Attention Service Bulletin 737-30-1056, dated February 28, 2007, provided the results of the resistance measurement meet the values specified in Revision 1; we have re-identified subsequent paragraphs accordingly. 

Comments 

We have considered the following comments on the NPRM. 

Request To Clarify the Proposed Applicability 

Boeing requests that we revise the Applicability statement of the NPRM to clarify the affected airplanes. Boeing states that airplanes having line numbers 1935 and subsequent have the bonding jumper installed during production and should not be subject to the NPRM. Boeing asserts that the NPRM should only be applicable to airplanes delivered with composite drain masts without the bonding jumper or airplanes with spare interchangeability notes allowing replacement of the aluminum drain masts with composite drain masts. 
We partially agree. For the reason stated by Boeing, we have determined that these airplanes should not be subject to this AD. However, we do not agree to revise the Applicability statement of this AD as suggested by Boeing. Instead, we have revised the Applicability statement of this final rule to state, "Boeing Model 737-600, -700, -700C, -800, and - 900 series airplanes, certificated in any category; as identified in Boeing Special Attention Service Bulletin 737-30-1056, Revision 1, dated October 25, 2007.'' We have confirmed that the effectivity of this service bulletin matches the applicability suggested by Boeing. 

Request To Revise the Proposed Costs of Compliance 

Air Transport Association (ATA), on behalf of its member American Airlines (AAL), states that the work-hour estimate of 9.75 hours per airplane provided in the service bulletin is more realistic than the 4- hour estimate provided in the NPRM. 
From this comment, we infer that AAL is requesting that we revise the Costs of Compliance section of the NPRM to reflect 9.75 work-hours per airplane to do the proposed actions. We do not agree. The cost information below describes only the direct costs of the specific actions required by this AD. Based on the best data available, the manufacturer provided the number of work hours (4) necessary to do the required actions. This number represents the time necessary to perform only the actions actually required by this AD. We recognize that, in doing the actions required by an AD, operators might incur incidental costs in addition to the direct costs. The cost analysis in AD rulemaking actions, however, typically does not include incidental costs such as the time required to gain access and close up, time necessary for planning, or time necessitated by other administrative actions. Those incidental costs, which might vary significantly among operators, are almost impossible to calculate. We have made no change to this final rule in this regard. 

Request To Include Parts Installation Requirement 

ATA, on behalf of its member Delta Airlines (Delta), suggests that the AD specify that a composite drain mast cannot replace an aluminum drain mast unless the bonding jumper is installed according to Boeing Special Attention Service Bulletin 737-30-1056, Revision 1, dated October 25, 2007. Delta asserts that, according to the airplane illustrated parts catalog, the composite and aluminum drain masts are interchangeable, which could lead to unintentional non-compliance with the AD. 
We agree that the composite and aluminum drain mast can be interchangeable. Therefore, for the reasons given by Delta, we have added a new paragraph (i), "Parts Installation,'' to this final rule to prohibit installation of a composite gray water drain mast, unless a bonding jumper is also installed, as specified in paragraph (g) of this final rule. 

Additional Changes to This Final Rule 

We have also updated the Costs of Compliance section of this final rule to reflect the current number of U.S.-registered airplanes, and the cost of parts necessary to accomplish the required actions. 

Costs of Compliance 

There are about 1,906 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD. 

Estimated Costs
 

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspection to determine gray water drain mast material	1	$80	None	$80	873	$69,840
Installation of bonding jumper	Between 2 and 4 (depending on airplane configuration)	$80	Between $8 and $16, depending on kit	Between $168 and $336	Up to 873	Between $146,664 and $293,328

Authority for This Rulemaking 

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 Findings 

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. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. 

Adoption of the Amendment 

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: 

PART 39--AIRWORTHINESS DIRECTIVES 

1. The authority citation for part 39 continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

Sec. 39.13 [Amended] 

2. The FAA amends Sec. 39.13 by adding the following new AD: