Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR 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 all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR series airplanes. This proposed AD would require a one-time inspection to determine whether any steel doubler (small or large) is installed at the lower forward and upper aft corners of the fuselage cutout at main entry doors (MEDs) number 3. Depending on the results of this inspection, this proposed AD also would require repetitive inspections for cracks of the skin, bearstrap, and small steel doubler (if installed) at the applicable corner or corners of the fuselage cutouts, and related investigative/corrective actions if necessary. This proposed AD also would provide the optional terminating action for the repetitive inspections of installing a large steel doubler at the affected corners. This proposed AD is prompted by reports of cracks in the skin and bearstrap at the upper aft corner and at the lower forward corner of the fuselage cutout at MEDs number 3. We are proposing this AD to detect and correct cracks in the skin, bearstrap, and small steel doubler (if installed), which could propagate and result in rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by October 31, 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.
• By 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-2005-22426; the directorate identifier for this docket is 2005-NM-105-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) 917-6590.

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 under ADDRESSES. Include “Docket No. FAA-2005-22426; Directorate Identifier 2005-NM-105-AD” in the subject line 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 submitted 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 website, 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 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 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 (DMS) receives them.

Discussion

We have received a report indicating that seven operators of the affected airplanes have found cracks in the skin and bearstrap at the upper aft corner of the fuselage cutout at main entry doors (MEDs) number 3. These cracks, which were between 0.6 inch and 2.5 inches in length, were found on airplanes that had accumulated between 12,140 and 23,927 flight cycles. We have received other reports indicating that some operators also found cracks in the skin and bearstrap at the lower forward corner of the fuselage cutout at MEDs number 3. These cracks were between 0.5 inch and 4.0 inches in length, and were found on airplanes that had accumulated between 11,986 and 23,083 flight cycles. Cracks in the skin, bearstrap, and small steel doubler, if not detected and corrected, could propagate and result in rapid decompression of the airplane.

Other Relevant Rulemaking

On December 8, 1992, we issued AD 92-27-04, amendment 39-8437 (57 FR 59801, December 16, 1992) for certain Boeing Model 747 series airplanes. [A correction of that AD was published in the Federal Register on February 17, 1993 (58 FR 8693)]. We issued that AD to prevent the structural degradation of the airplane by requiring various repetitive inspections of the airplane structure for cracks, and repair if any crack is found. AD 92-27-04 refers to Section 4 of Boeing Document No. D6-35999, Revision C, dated January 21, 1992, as the appropriate source of service information for doing the various inspections and repairs. Boeing Document No. D6-35999 in turn refers to Boeing Service Bulletin 747-53-2218, Revision 4, dated November 9, 1989, as the appropriate source of service information for doing the specific inspections of the lower forward corner of the fuselage cutout at MEDs number 3, and doing any necessary repairs. Installing a small or large steel doubler at the lower forward corner of the cutout in accordance with Boeing Service Bulletin 747-53-2218 terminates the repetitive inspection requirements of AD 92-27-04 for that area.

On April 22, 1993, we issued AD 93-08-12, amendment 39-8559, (58 FR 27927, May 12, 1993), for certain Boeing Model 747 series airplanes. That AD requires repetitive detailed visual internal inspections to detect cracks in various areas of the fuselage internal structure, and repair if necessary. Among other areas of the fuselage, AD 93-08-12 requires inspection of the upper aft and lower forward corners of the fuselage cutout at MEDs number 3, with and without steel doublers installed at those corners. Boeing Service Bulletin 747-53A2512, Revision 1, dated August 11, 2005, which is described below and cited as the appropriate source of service information for this new proposed AD, refers to AD 93-08-12. However, on May 14, 2002, we issued AD 2002-10-10, amendment 39-12756, (67 FR 36081, May 23, 2002) to supersede AD 93-08-12. AD 2002-10-10 retains the requirements of AD 93-08-12 for the area affected by this new proposed AD, but adds new repetitive inspections for cracking in certain areas of the upper chord of the upper deck floor beams, and repair if necessary. AD 93-08-12 and AD 2002-10-10 refer to Boeing Service Bulletin 747-53-2349, dated June 27, 1991, as the appropriate source of service information for doing the inspections and repair if necessary. In addition, on April 1, 2005, we issued a proposed AD that would supersede AD 2002-10-10. That proposed AD (Docket No. FAA-2005-20880, Directorate Identifier 2003-NM-229-AD, 70 FR 18332, April 11, 2005) would retain certain requirements of AD 2002-10-10 but add repetitive inspections for cracking of additional areas of the fuselage internal structure and related investigative/corrective actions.

Relevant Service Information

We have reviewed Boeing Service Bulletin 747-53A2512, including 747-53A2512, Revision 1, dated August 11, 2005. The service bulletin describes procedures for repetitive inspections to determine the size and presence of any steel doubler installed at the lower forward and/or upper aft corners of the fuselage cutout at MEDs number 3. If a large steel doubler was previously installed in accordance with Boeing Service Bulletin 747-53-2218 (described below), or the Boeing 747-100/200/300 Structural Repair Manual (SRM), Service Bulletin 747-53A2512 states that no further action is required for that corner. For lower forward corners that have no steel doubler installed, the service bulletin states that inspections and any applicable repairs are done in accordance with Boeing Service Bulletin 747-53-2218 (AD 92-27-04).

For all other corners and doubler configurations, the service bulletin gives various intervals for initial and repetitive inspections for cracks of the skin, bearstrap, and small steel doubler (if installed) at the lower forward and upper aft corners of the fuselage cutout at MEDs number 3. There are two options given in Boeing Service Bulletin 747-53A2512 for doing the initial and repetitive inspections. The first option is to do a detailed inspection. The second option is to do a high-frequency eddy current (HFEC) inspection. The service bulletin specifies that operators should also do a general visual inspection to detect cracks in the small steel doubler (if installed) and any previous repair trimouts in the bearstrap and skin at the same time as the initial detailed or HFEC inspection. The inspection thresholds and repetitive intervals specified in the service bulletin are described in the table below.

If the general visual inspection shows evidence of previous repair trimouts in the skin and/or bearstrap, the service bulletin gives procedures for doing a related investigative action. This related investigative action is doing an X-ray or detailed inspection for cracks at the repair trimouts. If no crack is found during the X-ray or detailed inspection, the service bulletin states that operators should repeat the applicable detailed or HFEC inspection at the applicable interval in the table above.

If any crack is found during any detailed, HFEC, or X-ray inspection, the service bulletin specifies that operators should do another related investigative action before further flight. This related investigative action is a dye penetrant or HFEC inspection to measure the crack length in order to determine the procedures for corrective action. After the crack length is determined, the service bulletin then specifies that operators should do the applicable corrective action before further flight. If all cracks are inside certain zones specified in the service bulletin, the corrective action is repairing the area by trimming out or stop-drilling the crack, and installing a large steel doubler at the applicable cutout corner. Installing a large steel doubler terminates the repetitive inspections for that corner. If any crack is outside certain zones specified in the service bulletin, the corrective action is asking Boeing for repair data so that the repair can be accomplished before further flight. The service bulletin also states that crack findings should be reported to Boeing.

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

Boeing Alert Service Bulletin 747-53A2512 refers to Boeing Service Bulletin 747-53-2218, Revision 4, dated November 9, 1989, as an additional source of service information for inspecting airplanes that do not have a steel doubler (large or small) installed at the lower forward corner of the fuselage cutout at MEDs number 3. AD 92-27-04 refers to Section 4 of Boeing Document No. D6-35999, Revision C, dated January 21, 1992 as the appropriate source of service information for doing the various inspections and repairs. Boeing Document No. D6-35999 in turn refers to Boeing Service Bulletin 747-53-2218, Revision 4, dated November 9, 1989, as the appropriate source of service information for doing the specific inspections of the lower forward corner of the fuselage cutout at MEDs number 3, and doing any necessary repairs.

Boeing has also issued Boeing Service Bulletin 53-2025, Revision 2, dated March 22, 1974. This service bulletin describes procedures for reinforcing the cutout at MEDs number 3.

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. Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and Boeing Service Bulletin 747-53A2512.”

Although installing a small steel doubler at the lower forward corner of the cutout at MED number 3 terminates the repetitive inspection requirements of AD 92-27-04 for that area, inspections of that area would again be required by this proposed AD. Installing a large steel doubler in that area in accordance with this proposed AD or in accordance with Boeing Service Bulletin 747-53-2218 would terminate the repetitive inspection requirements of both AD 92-27-04 and this proposed AD for that area. Although AD 92-27-04 allows installation of a small steel doubler, this proposed AD would not allow that action after the effective date of the proposed AD.

Differences Between the Proposed AD and Boeing Service Bulletin 747-53A2512

Boeing Service Bulletin 747-53A2512 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 after the effective date of this AD.

Boeing Service Bulletin 747-53A2512 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 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.

Although the Accomplishment Instructions of Boeing Service Bulletin 747-53A2512 describe procedures for reporting crack findings to Boeing, this proposed AD would not require those actions. We do not need this information from operators.

These differences have been coordinated with Boeing.

Clarification of Inspection Language

Boeing Service Bulletin 747-53A2512 refers to a “visual check of the MED number 3 cutout to determine if a small, large, or no steel doubler is installed.” We have determined that the procedures in the service bulletin should be described as a “general visual inspection.” The service bulletin includes a definition of this inspection.

Costs of Compliance

There are about 710 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

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. 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.