Airworthiness Directives; Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -300, -400, and -400D Series Airplanes; and Model 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 series airplanes. That AD currently requires a one-time inspection to determine the material type of the stop support fittings of the main entry doors (MEDs). That AD also currently requires repetitive detailed inspections to detect cracks of certain stop support fittings of the MEDs, and replacement of any cracked stop support fitting with a certain new stop support fitting. This proposed AD would add new inspections and replacement if necessary of the stop support fittings of MED 3, and add airplanes to the applicability. This proposed AD is prompted by reports of MED 3 having certain stop support fittings which are susceptible to stress corrosion cracking. We are proposing this AD to detect and correct stress corrosion cracking of the stop support fittings of the MEDs, which could result in damage to the adjacent forward edge frame of the door and consequent loss of a MED and rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by January 18, 2005.

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.

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 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.

FOR FURTHER INFORMATION CONTACT:

Technical information: 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) 917-6590.

Plain language information: Marcia Walters, marcia.walters@faa.gov.

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-2004-19796; Directorate Identifier 2004-NM-61-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 can 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 December 14, 1998, we issued AD 98-26-13, amendment 39-10954 (63 FR 70316, December 21, 1998), for certain Boeing Model 747-100, -100B, -200, -200B, -200C, -300, -400, and 747SR series airplanes having line numbers 1 through 830 inclusive. That AD requires a one-time inspection to determine the material type of the stop support fittings of the main entry doors (MEDs). That AD also currently requires repetitive detailed inspections to detect cracks of certain stop support fittings of the MEDs, and replacement of any cracked stop support fitting with a certain new stop support fitting. That AD was prompted by reports that stress corrosion cracking was found on certain stop support fittings of the MEDs. We issued that AD to detect and correct stress corrosion cracking of the stop support fittings of the MEDs, which could lead to failure of the stop support fittings, consequent loss of a MED, and rapid decompression of the airplane.

Actions Since Existing AD Was Issued

Since we issued AD 98-26-13, we received a report from the manufacturer that the new stop support fittings installed in production for MED 3 on airplanes after line number 830 may not have been made of the correct material type. In addition, the new stop support fittings supplied by Boeing as the replacement fitting for MED 3 may not have been made from the correct material type.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 747-53-2485, dated January 8, 2004. The service bulletin describes procedures for performing a high frequency eddy current (HFEC) inspection to determine the material type of the stop support fittings of MED 3. The service bulletin also describes procedures for repetitive visual inspections to detect cracks of the stop support fittings (not made from 7075-T73 or 7050-T7451 material) of MED 3, and replacement of any cracked fitting with a new fitting made from 7075-T73 or 7050-T7451 material. In addition, the service bulletin describes procedures for optional replacement of the stop support fittings of the MEDs with stop support fittings made from 7075-T73 or 7050-T7451 material, which would eliminate the need for repetitive inspections. The new stop support fitting is less susceptible to stress corrosion cracking.

The FAA has reviewed Boeing Service Bulletin 747-53-2358, Revision 1, dated April 19, 2001 (the original issue, dated August 26, 1993, is referenced as the appropriate source of service information for accomplishing AD 98-26-13). Revision 1 of the service bulletin describes procedures for performing an HFEC inspection to determine the material type of the stop support fittings of the MEDs. The service bulletin also describes procedures for repetitive visual inspections to detect cracks of the stop support fitting (not made from 7075-T73 or 7050-T7451 material) of the MEDs, and replacement of any cracked fitting with a new fitting made from 7075-T73 or 7050-T7451 material. In addition, the service bulletin describes procedures for optional replacement of the stop support fittings of the MEDs with stop support fittings made from 7075-T73 or 7050-T7451 material, which would eliminate the need for repetitive inspections. The new stop support fitting is less susceptible to stress corrosion cracking.

We have determined that accomplishment of the actions specified in the service information will adequately address the unsafe condition.

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 products of this same type design. Therefore, we are proposing this AD, which would supersede AD 98-26-13. This proposed AD would continue to require a one-time inspection to determine the material type of the stop support fittings of the MEDs. This proposed AD would also continue to require repetitive detailed inspections to detect cracks of certain stop support fittings of the MEDs, and replacement of any cracked stop support fitting with a certain new stop support fitting. This proposed AD would also require new inspections and replacement if necessary of the stop support fittings of MED 3 and add airplanes to the applicability. This proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and Service Bulletins.”

Differences Between the Proposed AD and Service Bulletins

For certain airplanes, Boeing Special Attention Service Bulletin 747-53-2485, dated January 8, 2004, specifies an inspection threshold of 6 years after the airplane was delivered or 18 months since the release of the service bulletin, whichever occurs later. However, for these same airplanes, paragraph (i) of the proposed AD specifies an inspection threshold of 72 months after the date of issuance of the original Airworthiness Certificate or the date of issuance of the original Export Certificate of Airworthiness, or 18 months after the effective date of the AD, whichever occurs later. This decision is based on our determination that the date the airplane was delivered may be interpreted differently by different operators. We find that our proposed terminology is generally understood within the industry and records will always exist that establish these dates with certainty.

Whereas Boeing Service Bulletin 747-53-2358, dated August 26, 1993; and Boeing Service Bulletin 747-53-2358, Revision 1, dated April 19, 2001; specify a “visual inspection,” the intent of the proposed AD is to require a “detailed inspection.” Additionally, a note has been added to the proposed AD to define that inspection.

Explanation of Change to Applicability

We have revised the applicability of the existing AD to identify model designations as published in the most recent type certificate data sheet for the affected models. In paragraphs (f) and (g) of the proposed AD, the model designation “747-100B SUD” has been added. There is no increase in the number of applicable airplanes for these paragraphs.

Clarification of Inspection Type

Although Boeing Special Attention Service Bulletin 747-53-2485, dated January 8, 2004, specifies a “detailed visual inspection,” this proposed AD requires a “detailed inspection.”

Clarification of Service Bulletin

Operators should also note that Boeing Service Bulletin 747-53-2358, Revision 1, dated April 19, 2001, specifies in the “Action” and “Description” paragraphs that you can end the repetitive inspections if you replace the stop support fittings with stop support fittings made from 7075-T73 or 7050-T7451 material. However, the Note under “Stop Support Fitting Replacement” of the Work Instructions of the service bulletin only specifies ending repetitive inspections if you replace with stop support fittings made from 7075-T73. Replacing with stop support fittings made of 7075-T73 or 7050-T7451 material does end the repetitive inspections as both are less susceptible to stress corrosion cracking.

Change to the Number of Airplanes in the Costs of Compliance

Operators should note that for AD 98-26-13 we estimated that there are about 575 airplanes of the affected design in the worldwide fleet and that about 164 airplanes of U.S. registry would be affected by that AD. However, for this proposed AD, which includes actions required by AD 98-26-13, we estimate that there are 814 airplanes of the affected design in the worldwide fleet and that 119 airplanes of U.S. registry would be affected by the proposed AD. The increase in the number of airplanes worldwide is due to the expanded applicability. The decrease in number of airplanes of U.S. registry may be due to a number of reasons such as retirement of airplanes and transfer of airplanes to foreign operators.

Change to Existing AD

This proposed AD would retain all requirements of AD 98-26-13. Since AD 98-26-13 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:

Costs of Compliance

There are about 814 airplanes of the affected design in the worldwide fleet. There are about 119 airplanes of U.S. registry that would be affected by this proposed AD. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Authority for This Rulemaking

The FAA's authority to issue rules regarding aviation safety is found in Title 49 of the United States Code. 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.

This rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, the FAA is charged 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 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.