Airworthiness Directives; Boeing Model 757-200, -200PF, and -200CB Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 757-200, -200PF, and -200CB series airplanes. This proposed AD would require inspections to detect scribe lines and cracks of the fuselage skin, lap joints, circumferential butt splice strap, and external and internal approved repairs; and related investigative/corrective actions if necessary. This proposed AD results from reports of scribe lines adjacent to the skin lap joints. We are proposing this AD to detect and correct cracks, which could grow and cause rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by April 30, 2007.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• 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 the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Dennis Stremick, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6450; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2007-27560; Directorate Identifier 2006-NM-211-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, 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 proposed AD. 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 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 of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

We have received reports of scribe lines found adjacent to the skin lap joints on Model 757-200 airplanes. The scribe lines appear to have been made on the skin when sealant was removed as part of preparation of the airplane for repainting. The airplanes had between 13,300 and 16,800 flight cycles. Although no cracks as a result of scribe lines have been reported on Model 757 airplanes, scribe lines have caused cracks on other airplanes. Undetected cracking, if not corrected, could grow and result in rapid decompression.

Related AD

This proposed AD is similar to AD 2006-07-12, amendment 39-14539 (71 FR 16211), March 31, 2006. That AD applies to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That AD requires a one-time inspection for scribe lines and cracks in the fuselage skin at certain lap joints, butt joints, external repair doublers, and other areas; and related investigative/corrective actions if necessary. That AD resulted from reports of fuselage skin cracks adjacent to the skin lap joints on airplanes that had scribe lines.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 757-53A0092, Revision 1, dated January 10, 2007. The service bulletin describes procedures for removing paint and sealant at the applicable zonal locations, and doing detailed inspections to detect scribe lines and cracks of the fuselage skin, lap joints, circumferential butt splice strap, and external and internal approved repairs. The service bulletin specifies repairing scribe lines before further flight, except when a limited return to service (LRTS) program for qualifying scribe lines would allow return to service for a limited period before scribe lines are repaired.

The LRTS program includes repetitive inspections to detect cracks where scribe lines were found. To qualify for an LRTS program, a scribe line must meet certain criteria including the total flight cycles on the airplane, and the location and extent of the scribe lines. The service bulletin specifies contacting Boeing for final repair instructions for the LRTS program, which would eliminate the need for the repetitive inspections of the LRTS program. The repetitive intervals for the LRTS program range from 1,500 to 8,000 flight cycles, depending on the location of the scribe lines and the configuration of the airplane.

Each piece of structure susceptible to a scribe line is assigned to a zone. Based on criticality of location, the service bulletin addresses the most critical areas (zones) first and appropriately reduces the compliance requirements for less critical areas. The service bulletin has specific instructions for calculating separate inspection thresholds. These thresholds are based on (1) fatigue life for the identified zonal locations and (2) potential scribe line opportunities in an airplane's maintenance history. The compliance times for inspecting are 20,000 flight cycles (Zone 1) and 30,000 flight cycles (Zone 2) after the first scribe opportunity. If a maintenance records-based threshold program is not used, however, the service bulletin specifies 6,000 flight cycles as the first scribe opportunity. Since a scribe line can occur at any time during the service life of an airplane and at many locations, the service bulletin uses both total flight cycles and structural criticality of locations to determine the inspection requirements.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed below.

Differences Between the Proposed AD and Service Information

The service bulletin specifies to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing those conditions by using a method that we approve, or by using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make those findings.

The service bulletin specifies compliance times relative to the date of issuance of the service bulletin; however, this proposed AD would require compliance before the specified compliance time relative to the effective date of the AD.

Costs of Compliance

There are about 945 airplanes of the affected design in the worldwide fleet; of these, about 634 are U.S.-registered airplanes. The following table provides the estimated costs for U.S. operators to comply with this proposed AD. There are no U.S.-registered airplanes in Group 5 or Group 6.

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 proposed AD 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.