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 inspections of certain wire bundles in the left and right engine-to-wing aft fairings for discrepancies, and related investigative and corrective actions if necessary. The original NPRM was prompted by a report indicating that a circuit breaker for the fuel shutoff valve tripped due to a wire that chafed against the structure in the flammable leakage zone of the aft fairing, causing a short circuit. This action revises the original NPRM by adding a new requirement for installing back-to-back p-clamps between the wire and hydraulic supply tube at the aft end of the right-hand strut only; and associated re-routing of the wire bundles, if necessary; and adding airplanes to the applicability. This action also clarifies the applicability specified in the original NPRM. We are proposing this supplemental NPRM to prevent chafing between the wire bundle and the structure of the aft fairing, which could result in electrical arcing and subsequent ignition of flammable vapors and possible uncontrollable fire.

DATES:

We must receive comments on this supplemental NPRM by August 1, 2005.

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.

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

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2004-19540; the directorate identifier for this docket is 2004-NM-110-AD.

FOR FURTHER INFORMATION CONTACT:

Thomas Thorson, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 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 under ADDRESSES. Include “Docket No. FAA-2004-19540; Directorate Identifier 2004-NM-110-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 our docket 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 can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

Examining the Docket

You can 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 (DMS) 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 November 5, 2004 (69 FR 64513). The original NPRM proposed to require inspections of certain wire bundles in the left and right engine-to-wing aft fairings for discrepancies, and related investigative and corrective actions if necessary. The original NPRM was prompted by a report indicating that a circuit breaker for the fuel shutoff valve tripped due to a wire that chafed against the structure in the flammable leakage zone of the aft fairing, causing a short circuit. Chafing between the wire bundle and the structure of the aft fairing could result in electrical arcing and subsequent ignition of flammable vapors and possible uncontrollable fire.

Comments

We have considered the following comments on the original NPRM.

Support for Original NPRM

One commenter states that it agrees with the actions specified in the original NPRM.

Request To Revise Service Information Referenced in the Original NPRM

Two commenters recommend that, due to additional findings by operators during accomplishment of the service bulletins referenced in the original NPRM, the service bulletins be revised with corrections to address certain discrepancies found in those bulletins. Subsequently Boeing revised the service bulletins. We have reviewed Boeing Alert Service Bulletins 757-28A0073 (for Model 757-200, -200CB, and -200PF series airplanes) and 757-28A0074 (For Model 757-300 series airplanes), both Revision 1, both dated February 24, 2005. (The original NPRM referenced Boeing Alert Service Bulletins 757-28A0073 and 757-28A0074, both dated November 20, 2003, as the appropriate sources of service information for accomplishing the proposed actions.) Revision 1 of the service bulletins adds provisions for installing back-to-back p-clamps between the wire and hydraulic supply tube at the aft end of the right-hand strut only; and performing associated re-routing of the wire bundles, if necessary. We have changed paragraphs (c) and (f) of this supplemental NPRM to reference Revision 1 of the service bulletins.

Request To Clarify Applicability

One commenter, the airplane manufacturer, asks that the applicability, specified in paragraph (c) of the original NPRM, be changed for clarification. The commenter states that the supplemental NPRM should apply only to Model 757 airplanes powered by Rolls-Royce engines, not Pratt & Whitney engines. The commenter adds that, for certain tasks, Revision 1 of the referenced service bulletins adds the last 13 airplanes to the applicability so that the entire 757 fleet powered by Rolls-Royce engines is included.

We agree with the commenter. The original NPRM refers to the effectivity identified in the referenced service bulletins; however, the applicability should be clarified to state that the supplemental NPRM is applicable only to airplanes with Rolls-Royce engines, as identified in Revision 1 of the referenced service bulletins. Paragraph (c) of this supplemental NPRM is changed accordingly. In addition, the total number of airplanes in the worldwide fleet specified in the original NPRM was incorrect. The original NPRM specified a total of 613 airplanes worldwide, but the airplane manufacturer has verified that the correct number of airplanes in the worldwide fleet should have been identified in the original NPRM as 605. Therefore, the correct number of airplanes for the supplemental NPRM is 618 worldwide and 342 of U.S. registry. We have changed those numbers in this supplemental NPRM.

Request To Add Repetitive Inspections of the Engine-to-Wing Aft Fairings

One commenter asks that operators be allowed to perform repetitive detailed visual inspections of the wire bundles in the engine-to-wing aft fairings instead of accomplishing the modification. The commenter supports its request by its inspection with minimal findings. The commenter adds that, in case of findings, the modification specified in the referenced service information should be performed as a terminating action. The commenter asks that the compliance time for the inspections be at intervals between 24 and 60 months. The commenter notes that the airplane manufacturer developed a maintenance schedule with repetitive inspections for its Model 757 special freighter airplanes at a C-check or 24 months, or 6,000 flight hours or 3,000 flight cycles.

We do not agree with the commenter. The configuration of several airplanes in the 757 fleet has been identified as having the potential to develop the unsafe condition specified in the original NPRM. The modification will ensure that the unsafe condition of chafing between the wire bundle and the structure of the aft fairing will not exist on additional airplanes in the fleet. However, under the provisions of paragraph (g) of this AD, affected operators may request approval of an alternative method of compliance (AMOC) for the relevant requirements. The request must include data substantiating that the AMOC would provide an acceptable level of safety. We have not changed the supplemental NPRM in this regard.

Request To Allow Compliance With Referenced Service Information

One commenter states that some pylon configurations already have the correct wire routing and need only a bracket with part number P/N 313N5033-134 installed in order to comply with the modification specified in the service information referenced in the original NPRM. The commenter does not provide any request.

We acknowledge the commenter's concern and offer the following response. The referenced service information is sufficiently comprehensive to allow completion of the corrective actions for all delivered airplane configurations, including the recommended provisional work instructions, which will reduce the quantity of AMOC approval requests by operators. We have approved Revision 1 of the service bulletins, as specified previously, and revised the original NPRM to refer to Revision 1. We hope this change will address the commenter's concern.

Request To Address Technical Disparity

The same commenter suggests that we address a technical disparity between the service information referenced in the original NPRM and aircraft drawings 288N3121 and 288N3122. The commenter notes that Step 3 of Figure 2 of the original issue of Service Bulletin 757-28A0073 specifies inspection and possible replacement of caterpillar grommet P/N BACG20Z-E on the pylon bulkhead at power plant station 278. The commenter adds that this pylon bulkhead is a flanged hole, and the drawings specify the use of caterpillar grommet P/N BACG20AD for the flanged holes. The commenter adds that it has verified that P/N BACG20Z-E will not fit on the pylon bulkhead at power plant station 278.

We acknowledge the commenter's concern. P/N BACG20Z-E has been verified by the manufacturer to be the P/N installed during production, and installation of this part per the referenced service bulletin has been validated in-service. The installation steps have been clarified in Revision 1 of the referenced service bulletin, and the manufacturer has verified that the Illustrated Parts Catalog reflects the same part number specified in the service bulletin. In addition, the referenced drawings authorize installation of either P/N BACG20Z-E or P/N BACG20AD by general note. We have received data substantiating that the commenter's issues have been addressed through coordination with the manufacturer. We have not changed the supplemental NPRM in this regard.

Request for Approval of Future Service Bulletin Revisions

One commenter asks that a statement be included in the supplemental NPRM allowing the use of later FAA-approved revisions of the referenced service information. The commenter states that this will allow operators to use FAA-approved revisions without requesting an AMOC.

We do not agree with the commenter. We cannot accept as-yet unpublished service documents for compliance with the requirements of an AD. Referring to an unavailable service bulletin in an AD to allow operators to use later revisions of the referenced documents (issued after publication of the AD) violates Office of the Federal Register regulations for approving materials that are incorporated by reference. It should be noted that when we approve AD-related service information, an AMOC is usually issued to the manufacturer to authorize use of the new bulletin, thus precluding the need for operators to submit AMOC requests. We have not changed the supplemental NPRM in this regard.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

The 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 supplemental NPRM.

Costs of Compliance

There are about 618 airplanes of the affected design in the worldwide fleet. This supplemental NPRM would affect about 342 airplanes of U.S. registry. The proposed actions would take between 16 and 44 work hours per airplane, depending on airplane configuration, at an average labor rate of $65 per work hour. Required parts would cost about $600 per airplane. Based on these figures, the estimated cost of this supplemental NPRM on U.S. operators is between $560,880 and $1,183,320, or between $1,640 and $3,460 per airplane.

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. 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.