Airworthiness Directives; Boeing Model 747 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 inspections to detect cracks in the front spar pressure bulkhead chord, and repair, if necessary. This proposed AD would require repetitive high frequency eddy current (HFEC) inspections of the body station (BS) 1000 bulkhead chord for cracks, repetitive detailed inspections of the bathtub fittings, if installed, for cracks, and corrective action, if necessary. Accomplishment of new inspections would end the inspections of the existing AD. This proposed AD would also revise the applicability of the existing AD to include additional airplanes. This proposed AD is prompted by reports of cracks in the BS 1000 bulkhead chord. We are proposing this AD to detect and correct fatigue cracks in the BS 1000 bulkhead chord, which, if not repaired before they reach critical length, could result in the failure of the adjacent structure and skin and lead to in-flight depressurization 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.

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: Nick Kusz, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6432; 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-2004-19538; Directorate Identifier 2003-NM-99-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 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.

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 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 DMS receives them.

Discussion

On April 19, 1990, we issued AD 90-09-09, amendment 39-6586 (55 FR 17928, April 30, 1990), for certain Boeing Model 747 series airplanes (a correction of that AD was published in the Federal Register on May 21, 1990 (55 FR 20894)). That AD requires repetitive high frequency eddy current (HFEC) inspections to detect cracks in the front spar pressure bulkhead chord, and repair, if necessary. That AD was prompted by a determination that accomplishing a certain modification may result in fuel leakage from the wing center section fuel tank. We issued that AD to prevent a potential fire hazard in the forward cargo compartment.

Actions Since Existing AD was Issued

Since we issued AD 90-09-09 (applicable to Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, and -200F series airplanes, line numbers 1 through 201 inclusive), we have received reports of cracks in the body station (BS) 1000 bulkhead chord of Boeing Model 747 series airplanes after line number 201. We have also received reports of cracking in the chords of airplanes that received the chord replacement per Boeing Service Bulletin 747-53-2362, dated March 26, 1992 (for Model 747-100, -100B, -100B SUD, -200B, -200C, and -200F series airplanes, line numbers 1 through 201 inclusive). Boeing Service Bulletin 747-53-2362 was intended to address cracking in the chord. Fatigue cracking in the BS 1000 bulkhead chord, if not repaired before they reach critical length, could result in the failure of the adjacent structure and skin and lead to in-flight depressurization of the airplane.

Related ADs Due to Common Access

On May 23, 2000, we issued AD 2000-11-07 (65 FR 34932, June 1, 2000), applicable to certain Boeing Model 747-200, -300, and -400 series airplanes, that requires repetitive HFEC inspections to detect cracking of the front spar web of the center section of the wing, and repair, if necessary.

On October 19, 2001, we issued AD 2001-22-04 (66 FR 54422, October 29, 2001), applicable to all Boeing Model 747 series airplanes, that requires repetitive inspections for cracking of the fuselage skin adjacent to the drag splice fitting, and follow-on actions, if necessary.

The inspections in the above ADs may be accomplished concurrently with this proposed AD due to common access but they are not required by this AD.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2471, dated March 27, 2003. The service bulletin describes procedures for performing repetitive HFEC inspections of the BS 1000 bulkhead chord for cracks; performing repetitive detailed inspections of the bathtub fittings, if installed, for cracks; and corrective action, if necessary. Accomplishing the inspections would end the inspections required by AD 90-09-09. The corrective action includes replacing the BS 1000 bulkhead chord with a new chord and replacing the bathtub fittings with new bathtub fittings.

Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

The service bulletin also recommends concurrent accomplishment, due to common access, of the inspections specified in Boeing Service Bulletin 747-53A2444 (Boeing Service Bulletin 747-53A2444, Revision 1, dated June 15, 2000; and Boeing Alert Service Bulletin 74753A2444, Revision 2, dated May 24, 2001, are listed as relevant sources of service information for AD 2001-22-04); Boeing Service Bulletin 747-57-2297; and Boeing Service Bulletin 747-57A2298 (Boeing Alert Service Bulletin 747-57A2298, Revision 1, dated September 12, 1996; Boeing Service Bulletin 747-57A2298, Revision 2, dated October 2, 1997; and Boeing Alert Service Bulletin 747-57A2298, Revision 3, dated January 7, 1999; are listed as relevant sources of service information for AD 2000-11-07). These service bulletins are not required by this AD.

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 90-09-09. This proposed AD would continue to require repetitive HFEC inspections to detect cracks in the front spar pressure bulkhead chord, and repair, if necessary. This proposed AD would also require repetitive HFEC inspections of BS 1000 bulkhead chord for cracks, repetitive detailed inspections of the bathtub fittings, if installed, for cracks, and corrective action, if necessary. Accomplishment of new inspections would end the inspections of the existing AD. The proposed AD would also revise the applicability of the existing AD to include additional airplanes. This proposed AD would require you to use the service information described previously to perform these actions except as discussed under “Difference Between the Proposed AD and the Service Bulletin.”

Difference Between the Proposed AD and the Service Bulletin

Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposed AD would require the repair of those conditions to be accomplished per a method approved by the FAA.

Clarification of Inspection Type

Where Boeing Alert Service Bulletin 747-53A2471, dated March 27, 2003, specifies to do a “detailed visual inspection,” this proposed AD specifies to do a “detailed inspection.” We have also added a note to the proposed AD to clarify the definition of detailed inspection.

Changes to Existing AD

This proposed AD would retain the requirements of AD 90-09-09. However, 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 1,350 Model 747 series airplanes worldwide of the affected design. This proposed AD would affect about 245 airplanes of U.S. registry.

The actions that are required by AD 90-09-09 and retained in this proposed AD take about 84 work hours per airplane, at an average labor rate of $65 per work hour. We estimate 102 airplanes of U.S. registry are affected by AD 90-09-09. Based on these figures, the estimated cost of the currently required actions is $556,920, or $5,460 per airplane, per inspection cycle.

The new proposed inspections would take about 14 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the new actions specified in this proposed AD for U.S. operators is $222,950, or $910 per airplane, per inspection cycle.

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.