Airworthiness Directives; Boeing Model 757 Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

The FAA is revising an earlier proposed airworthiness directive (AD) for certain Boeing Model 757 airplanes. The original NPRM would have required, for certain airplanes, reworking the spar bonding path and reapplying sealant; and, for certain other airplanes, testing the electrical bond between the engine fuel feed hose and the wing front spar and, if applicable, reworking the spar bonding path and reapplying sealant. The original NPRM also would have required, for all airplanes, an inspection to ensure the electrical bonding jumper is installed between the engine fuel feed tube and the adjacent wing station. The original NPRM resulted from fuel system reviews conducted by the manufacturer. This action revises the original NPRM by requiring operators that may have installed an incorrect O-ring to install the correct part and do a re-test. We are proposing this supplemental NPRM to prevent arcing or sparking at the interface between the bulkhead fittings of the engine fuel feed tube and the front spar during a lightning strike, which could provide a possible ignition source for the fuel vapor inside the fuel tank and result in a fuel tank explosion.

DATES:

We must receive comments on this supplemental NPRM by May 1, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this supplemental NPRM.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, Room PL-401, Washington, DC 20590.
• Fax: (202) 493-2251.
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Tom Thorson, Aerospace Engineer, Propulsion Branch, ANM-140S, Seattle Aircraft Certification Office, FAA,1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6508; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this supplemental NPRM. Send your comments to an address listed in the ADDRESSES section. Include the docket number “Docket No. FAA-2005-20689; Directorate Identifier 2004-NM-197-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this supplemental NPRM. We will consider all comments received by the closing date and may amend this supplemental NPRM in light of those comments.

We will post all comments submitted, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this supplemental NPRM. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level in the Nassif Building at the DOT street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

We proposed to amend 14 CFR part 39 with a notice of proposed rulemaking (NPRM) for an AD (the “original NPRM”) for certain Boeing Model 757 airplanes. The original NPRM was published in the Federal Register on March 23, 2005 (70 FR 14594). The original NPRM proposed to require, for certain airplanes, reworking the spar bonding path and reapplying sealant; and, for certain other airplanes, testing the electrical bond between the engine fuel feed hose and the wing front spar and, if applicable, reworking the spar bonding path and reapplying sealant. The original NPRM also proposed to require, for all airplanes, an inspection to ensure the electrical bonding jumper is installed between the engine fuel feed hose and the adjacent wing station.

Actions Since Original NPRM Was Issued

Since we issued the original NPRM, the manufacturer informed us that a part number (P/N) for an O-ring installation was identified incorrectly in Boeing Alert Service Bulletin 757-28A0076 and Boeing Alert Service Bulletin 757-28A0077, both dated August 27, 2004. These service bulletins were referenced as the appropriate source of service information for accomplishing the required actions in the original NPRM. This supplemental NPRM (SNPRM) will propose to require compliance with Revision 1 of the service bulletins, which cite the O-ring's P/N correctly. For Group 1 airplanes on which the installation was done in accordance with the original issue of the service bulletins, and for Group 2 airplanes that failed the bonding resistance test done in accordance with the original NPRM, this SNPRM will propose to require installing an O-ring with the correct P/N and doing a re-test.

Relevant Service Information

We have reviewed Boeing Service Bulletin 757-28A0076, Revision 1, dated October 20, 2005; and Boeing Service Bulletin 757-28A0077, Revision 1, dated October 20, 2005. The service bulletins describe procedures that are essentially the same as those described in the original NPRM, except the service bulletins, Revision 1, identify the correct part number for the O-ring. However, the service bulletins describe additional work for airplanes that incorporated the initial releases of the service bulletins. The additional work includes disassembling the coupling for the engine fuel feed tube at the front spar (left and right wings), and replacing the O-ring that has the incorrect P/N with a new O-ring with the correct P/N. The additional work also includes doing a leak test of the re-assembled coupling. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

Comments

We have considered the following comments about the original NPRM.

Request To Extend Compliance Time

The Air Transport Association (ATA), Continental Airlines, United Airlines, Delta Airlines, U.S. Airways, and American Airlines request that we extend the proposed compliance time for doing the bonding resistance test and for inspecting the electrical bonding jumper. The commenters request that we extend the compliance time from 48 months to either 60 months or 72 months. The commenters request the extension to all of the AD actions to be scheduled to coincide with heavy maintenance intervals when other activities that require entering the fuel tank are also scheduled. The commenters state that extending the compliance time would minimize the number of fuel tank entries and also minimize the manpower requirements for draining the tank and doing entry procedures. Several commenters note that AD 2004-10-06, amendment 39-13636 (69 FR 28046, May 18, 2004), which is a similar AD for hydraulic tube bonding in the fuel tank for lightning protection, has a compliance time of 60 months, which provides an adequate level of safety. One commenter notes that there have been no large-jet transport accidents related to lightning strikes or bonding-related hazards since 1977, when the FAA strengthened certification standards for bonding. The same commenter notes that there have been no lightning-induced fuel tank events on Boeing Model 757 airplanes.

We partially agree with the commenters. We agree with extending the compliance time to 60 months because we have assessed these specific actions on other Boeing airplane models and we have evaluated similar ADs such as AD 2004-10-06, and AD 2005-04-01, amendment 39-13973 (70 FR 7841, February 16, 2005). In addition, we find that extending the compliance time will not adversely affect safety. The manufacturer supports extending the compliance time to 60 months, and Revision 1 of Boeing Service Bulletins 757-28A0076 and 757-28A0077 include this revised time. We do not agree with extending the compliance time to 72 months. The commenters that request this extension do not provide a technical justification; however, operators may request an alternate method of compliance (AMOC) in accordance with the procedures in paragraph letter (l) of this proposed AD.

Request To State that Bonding Jumper Is Attached to a Fuel Tube

The Boeing Company requests that we revise three sections of the proposed AD in order to correctly identify that the bonding jumper is attached to a fuel tube mating with a fuel hose end fitting, and not with the fuel hose. Boeing states that this change will clarify that the electrical bonding jumper is installed between the engine fuel feed tube and the adjacent wing section.

We agree. The suggested wording will clarify the proposed AD. We have changed the “Summary” section and paragraph (i) of the proposed AD as requested. However, we have not changed the “Relevant Service Information” section because that section of the SNPRM does not contain the same information as the same section of the original NPRM.

Request To Correct Discrepancies in Service Bulletins

Continental Airlines states that the Work Instructions in Boeing Alert Service Bulletins 757-28A0076 and 757-28A0077, both dated August 27, 2004, have discrepancies that prevent accomplishing certain proposed actions. Specifically, the following items are not included in the alert service bulletins: Removal and installation instructions for the forward flap track fairing; a statement that a special tool is required for removing and reinstalling the forward fitting of the fuel feedline; and a note to clarify that leak tests of the fuel system are required following rework. Continental states that alternative rework instructions would have to be approved as AMOCs for each airplane to comply successfully with the requirements of the proposed AD.

We partially agree. We agree that a note that leak tests of the fuel system are necessary following rework would clarify the service bulletin; Boeing has added this note to Revision 1 of Boeing Service Bulletins 757-28A0076 and 757-28A0077. Also, Boeing verified that a special tool is not necessary because a standard “crow's foot” tool is readily available that is sufficient to complete the task. In addition, the instructions for removing and reinstalling the forward fitting are already included in the service bulletins by reference to the applicable airplane maintenance manuals (AMM). Boeing can answer additional questions if the commenter requires further information. We disagree that it is necessary for us to mandate the changes proposed by Continental because these changes have to do with the content of the service bulletins rather than the content of this proposed AD, and they do not affect the AD action. No changes to the proposed AD are necessary.

Request To Revise Cost Estimate

The ATA, American Airlines, and Delta Airlines request that we revise the hours estimated to complete the proposed actions. The commenters state that the estimates do not accurately reflect the operations required for defueling, access, and other prerequisites for the proposed actions.

We disagree. The cost estimate discussed in AD rulemaking actions represents only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. However, Boeing updated the work-hour estimates for the bonding test and sealant application, and for the bonding test, hose fitting and spar bonding rework, and sealant application. These changes are reflected in the Cost Estimate table below.

In addition, after the original NPRM was issued, we reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $65 per work hour to $80 per work hour. The costs of compliance, below, reflect this increase in the specified hourly labor rate.

Request To Remove Rework Requirement for Certain Conditions

Delta Airlines states that, for certain airplanes, Boeing Alert Service Bulletins 757-28A0076 and 757-28A0077 require removing, cleaning, and re-installing the fuel feedline fitting to ensure an adequate bond is present for lightning protection. Delta requests that we revise the proposed AD to require reworking the fitting only if a preliminary resistance measurement fails. Delta states that the proposed AD does not take into account installations that may have been completed per the revised AMM procedures, which are consistent with the service information.

We disagree. The resistance measurement by itself does not ensure that an adequate bond is present for lightning protection. The only way to ensure the presence of an adequate bond capable of carrying the heavy electrical currents that are caused by an attached lightning strike is by a rigorous cleaning and assembly process, with an electrical bonding check as a final measure to ensure proper assembly. However, interested parties may submit an AMOC in accordance with the procedures in paragraph letter (l) of this proposed AD, if they can substantiate the following: That an airplane has a fuel feedline fitting that is installed in accordance with a procedure equivalent to the service bulletins referenced in the proposed AD; and that the current resistance measurement is within the value required by the service bulletins. No changes to the proposed AD are necessary.

Request To Revise “Discussion” Section

The Boeing Company requests that we revise the “Discussion” section to be similar to that provided in NPRM Docket No. FAA-2004-19680 (69 FR 68272, November 24, 2004). Boeing states that the issue addressed in this proposed AD is similar to that in NPRM Docket No. FAA-2004-19680 in that it was identified before the SFAR 88 safety assessment. Boeing states that the “Discussion” section does not reflect this fact.

We disagree. Although the issue was identified before the Special Federal Aviation Regulation No. 88 (“SFAR 88,” Amendment 21-78, and subsequent Amendments 21-82 and 21-83) safety assessment, the non-compliance was identified and included in the Boeing 757 SFAR 88 Safety Analysis documents. This non-compliance was tracked administratively and identified as an unsafe condition requiring AD action through the SFAR 88 process. Therefore, it is considered an SFAR 88-related AD. No changes to the proposed AD are necessary.

FAA's Determination and Proposed Requirements of the SNPRM

Certain changes discussed above expand the scope of the original NPRM; therefore, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment on this SNPRM.

Difference Between the SNPRM and the Service Bulletins

Although the referenced service bulletins would allow an operator's equivalent procedures to be used for aircraft maintenance manuals (AMM) referenced in the service bulletins, this proposed AD would require you to use the referenced AMMs except as provided in paragraph (k) of this SNPRM.

Clarification of AMOC Paragraph

We have revised this action to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

Costs of Compliance

There are about 1,040 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 700 airplanes of U.S. registry. The average labor rate is estimated to be $80 per work hour. Parts would be supplied from operator stock. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

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

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the 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.

We prepared a regulatory evaluation of the estimated costs to comply with this supplemental NPRM and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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.