Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SP, and 747SR Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) for certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SP, and 747SR series airplanes. That AD currently requires one-time inspections for cracking in certain upper deck floor beams and follow-on actions. This proposed AD would expand the existing inspection area, and would require inspecting fastener holes in certain areas of airplanes modified previously, and taking corrective actions if necessary. This action also would define new sources for instructions for repairs and post-modification/repair inspections. This proposed AD is prompted by reports of fatigue cracking of the upper chord of certain upper deck floor beams. We are proposing this AD to find and fix cracking in certain upper deck floor beams, which could extend and sever floor beams adjacent to the body frame and result in rapid depressurization and loss of controllability of the airplane.

DATES:

We must receive comments on this proposed AD by December 20, 2004.

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.

You can get the service information identified in this proposed AD from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You may examine the contents of this AD docket on the Internet at http://dms.dot.gov , or 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-2004-19535; the directorate identifier for this docket is 2004-NM-78-AD.

FOR FURTHER INFORMATION CONTACT:

Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6437; fax (425) 917-6432.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-19535; Directorate Identifier 2004-NM-78-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 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 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 .

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov .

Examining the Docket

You may examine the AD docket 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 DMS receives them.

Discussion

On August 30, 2002, we issued AD 2002-18-04, amendment 39-12878 (67 FR 57510, September 11, 2002), for certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SP, and 747SR series airplanes. That AD requires one-time inspections for cracking in certain upper deck floor beams and follow-on actions. That AD was prompted by reports of fatigue cracking on the left and right ends of the upper chord of the station (STA) 340 upper deck floor beam on several Boeing Model 747 series airplanes. We issued that AD to find and fix cracking in certain upper deck floor beams. Such cracking could extend and sever floor beams adjacent to the body frame and result in rapid depressurization and loss of controllability of the airplane.

Relevant Service Information

We've reviewed Boeing Service Bulletin 747-53A2459, Revision 1, dated March 11, 2004. Revision 1 of the service bulletin describes certain inspection procedures that are similar to those described in Boeing Alert Service Bulletin 747-53A2459, dated January 11, 2001, which AD 2002-18-04 refers to as the applicable source of service information for certain actions required by that AD. Revision 1 of the service bulletin, however, expands the inspection area to include fastener holes inboard of the body frame.

Part 5 of Revision 1 of the service bulletin describes procedures for post-modification/repair inspections. These inspections use the open-hole high-frequency eddy current (HFEC) inspection method. These inspections are intended to find cracking of the STA 340 and STA 360 upper deck floor beams at fastener holes common to the upper chord, reinforcement straps, and body frame. The service bulletin also describes procedures for surface HFEC inspections for cracking along the lower edge of the upper chord and reinforcement straps of the floor beams, which you can use as an alternative to the post-modification/repair open-hole HFEC inspections. (AD 2002-18-04 specifies that you must do post-modification/repair inspections in accordance with a method that we approve, or in accordance with data meeting the type certification basis of the airplane approved by an authorized Boeing Company Designated Engineering Representative (DER).) The service bulletin specifies repeating the inspection at intervals of 1,000 flight cycles (if you used the surface HFEC method for the most recent inspection), or 3,000 or 6,000 flight cycles, depending on fastener location (if you used the open-hole HFEC method for the most recent inspection).

Part 5 of the service bulletin also describes procedures for corrective actions if you find cracking during the post-modification/repair inspections. These corrective actions include repairing cracking of the floor beam and body frame, or replacing, with new parts:

• The outboard end of the upper chord (if you find cracking of the upper chord).
• The outboard end of the web (if you find cracking of the floor beam web).
• The reinforcement strap (if you find cracking of the reinforcement strap).

Part 6 of Revision 1 of the service bulletin describes procedures for doing a one-time open-hole HFEC inspection of the fastener holes common to the reinforcement straps on airplanes that were modified in accordance with the original issue of the service bulletin, and taking corrective actions if necessary. The corrective actions in Part 6 are the same as those in Part 5, which we describe in the preceding paragraph.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We've evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. Therefore, we're proposing this AD, which would supersede AD 2002-18-04. This proposed AD would continue to require one-time inspections for cracking in certain upper deck floor beams, and other specified actions. This proposed AD would expand the existing inspection area to include fastener holes inboard of the body frame, and would require performing a one-time inspection for cracking of fastener holes in certain areas of airplanes modified previously, and taking corrective actions if necessary. This action also would define new sources for instructions for repairs and post-modification/repair inspections. This proposed AD would require you to use the service information described previously to do these actions, except as discussed under “Differences Between the Proposed AD and Service Bulletin.”

Differences Between the Proposed AD and Service Bulletin

The service bulletin specifies doing the initial post-modification/repair inspections in accordance with Figures 12 and 13 of the service bulletin within 6,000 flight cycles after doing the modification or permanent repair. We've added a grace period of 1,000 flight cycles after the effective date of this AD for this inspection, to ensure that operators of airplanes that have accumulated close to or more than 6,000 flight cycles since the modification or permanent repair was done have sufficient time to perform these proposed inspections.

The service bulletin specifies that you may contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require you to repair those conditions in one of the following ways:

• Using a method that we approve; or
• Using data that meet the type certification basis of the airplane, and that have been approved by a Boeing Company DER whom we've authorized to make such findings.

Although the Accomplishment Instructions of Boeing Service Bulletin 747-53A2459, Revision 1, describe procedures for reporting certain body frame cracks found on certain airplanes, this proposed AD would not require those actions. We don't need this information from operators.

For airplanes inspected previously in accordance with Boeing Alert Service Bulletin 747-53A2459 (but not previously modified or repaired), Boeing Service Bulletin 747-53A2459, Revision 1, does not specify a compliance time for inspecting the fastener holes inboard of the body frame that were added in Revision 1. Paragraph (j) of this proposed AD specifies these compliance times for that inspection:

In developing an appropriate compliance time for this inspection, we considered the manufacturer's recommended compliance times for the other inspections in this proposed AD, and the degree of urgency associated with the subject unsafe condition. In light of these factors, we find that the specified compliance times represent an appropriate interval of time for affected airplanes to continue to operate without compromising safety.

Changes to Existing AD

This proposed AD would retain all requirements of AD 2002-18-04. Since AD 2002-18-04 was issued, the AD format has been revised, and certain paragraphs have been rearranged. As a result, the corresponding paragraph identifiers have changed in this proposed AD, as listed in the following table:

Also, AD 2002-18-04 estimated that the number of work hours necessary for the post-modification/repair inspection was 8 work hours per inspection cycle. We reached that estimate based on the best-available data at the time. As explained previously, Revision 1 of the service bulletin includes procedures for these inspections and estimates that they will take about 24 work hours. We've revised the “Costs of Compliance” section of this proposed AD accordingly.

Costs of Compliance

This proposed AD would affect about 433 airplanes worldwide. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

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. 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.