E7-13263. Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP 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 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. This proposed AD would require repetitive inspections for cracking of the station (STA) 1241 bulkhead fittings just above the canted pressure deck; a one-time determination of the edge margin at seven fastener positions on each side of the airplane; and related investigative/corrective actions if necessary. This proposed AD results from a report that an operator found a 1.65-inch crack on the STA 1241 bulkhead fitting on the left side of a Boeing Model 747-200F series airplane that had accumulated 17,332 total flight cycles. We are proposing this AD to detect and correct cracking in the STA 1241 bulkhead fittings, which could result in reduced structural integrity of the airplane.

DATES:

We must receive comments on this proposed AD by August 23, 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: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue SE., 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:

Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

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-2007-28620; Directorate Identifier 2007-NM-090-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 airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone [phone]) is located on the ground floor of the West Building at the street address stated in the ADDRESSES section.

Discussion

We have received a report that an operator found a 1.65-inch crack on the station (STA) 1241 bulkhead fitting on the left side of a Boeing Model 747-200F series airplane that had accumulated 17,332 total flight cycles. The crack was at a fastener hole just above the canted pressure deck. The STA 1241 fitting was replaced on this airplane. The STA 1241 bulkhead fittings on Model 747 airplanes are 140-inch long aluminum forgings that extend from stringer 19 down through the pressure deck and attach to the wing rear spar. Cracking in the STA 1241 bulkhead fittings, if not found and repaired, can become large and result in reduced structural integrity of the airplane.

Other Relevant Rulemaking

On January 16, 1990, we issued AD 90-06-06, amendment 39-6490, (55 FR 8374, March 7, 1990), for certain Boeing Model 747 series airplanes listed in Boeing Document No. D6-35999, dated March 31, 1989. That AD requires, among other actions, replacement of the STA 1241 bulkhead splice straps in accordance with Boeing Service Bulletin 747-53-2283, Revision 3, dated November 1, 1989. We issued that AD to prevent structural failure of the affected airplanes. The date of that replacement is used to determine the compliance threshold for certain airplanes affected by this proposed AD.

On March 18, 1992, we issued AD 92-08-02, amendment 39-8213 (57 FR 12869, April 14, 1992), for certain Boeing Model 747 airplanes. That AD requires repetitive inspections of the STA 1241 bulkhead splice straps in accordance with Boeing Service Bulletin 747-53-2283, Revision 3, dated November 1, 1989, and repair if necessary. Boeing Service Bulletin 747-53-2219 is an alternative method of compliance (AMOC) for certain repairs required by that AD. The date of modification in accordance with Boeing Service Bulletin 747-53-2219 is used to determine the compliance threshold for certain airplanes affected by this proposed AD.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2658, dated February 22, 2007. The service bulletin describes procedures for doing repetitive inspections (internal surface high frequency eddy current and external ultrasonic) for cracking of the STA 1241 bulkhead fittings just above the canted pressure deck. The service bulletin also specifies a one-time determination of the edge margin at seven fastener positions on each side of the airplane. If the edge margin of a fastener hole is less than 1.35 times the diameter of the hole, the related investigative/corrective action is contacting Boeing for special inspection data. For any crack found during a repetitive inspection, the corrective action is contacting Boeing for repair data.

The compliance threshold for doing the initial inspection varies according to the configuration of the airplane, and according to the date of previous splice strap replacement or date of previous bulkhead modification as described above under “Other Relevant Rulemaking.” The thresholds described in Boeing Alert Service Bulletin 747-53A2658 are as follows:

• For airplanes in the original configuration, or as modified in accordance with Boeing Service Bulletin 747-53-2219 (AMOC for AD 92-08-02): Before the accumulation of 10,000 total flight cycles, or 1,500 flight cycles after the effective date on Boeing Alert Service Bulletin 747-53A2658, whichever occurs later.
• For airplanes modified in accordance with Boeing Service Bulletin 747-53-2283 (AD 90-06-06): Before the accumulation of 5,000 flight cycles since modification in accordance with Boeing Service Bulletin 747-53-2283, or within 1,500 flight cycles after the date on Boeing Alert Service Bulletin 747-53A2658, whichever occurs later.

The compliance time for doing the first repeat inspection varies according to the smallest calculated edge margin at the seven fastener positions on each side of the airplane. The earliest specified range for doing the first repetitive inspection is before the accumulation of 11,500 total flight cycles, or within 1,500 flight cycles since the initial inspection, whichever occurs later. The latest specified range for doing the first repeat inspection is before the accumulation of 15,000 total flight cycles, or within 5,000 flight cycles since the initial inspection, whichever occurs later. Afterward, the repetitive intervals range from intervals not to exceed 1,500 flight cycles, to intervals not to exceed 5,000 flight cycles.

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 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 under “Difference Between the Proposed AD and the Service Bulletin.”

Difference Between the Proposed AD and the Service Bulletin

The service bulletin specifies to contact the manufacturer for instructions on how to do certain inspections and repairs, but this proposed AD would require inspection or repair 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.

Costs of Compliance

There are about 455 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 133 airplanes of U.S. registry. The proposed actions would take about 14 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $148,960, or $1,120 per airplane, per inspection cycle.

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.

§ 39.13

[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-28620; Directorate Identifier 2007-NM-090-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by August 23, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2658, dated February 22, 2007.

Unsafe Condition

(d) This AD results from a report that an operator found a 1.65-inch crack on the station (STA) 1241 bulkhead fitting on the left side of a Boeing Model 747-200F series airplane that had accumulated 17,332 total flight cycles. We are issuing this AD to detect and correct cracking in the STA 1241 bulkhead fittings, which could result in reduced structural integrity of the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspections and Corrective Action

(f) At the applicable time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2658, dated February 22, 2007: Do internal surface high-frequency eddy current and external ultrasonic inspections for cracking of the STA 1241 bulkhead fittings just above the canted pressure deck; determine the edge margin at seven fastener positions on each side of the airplane; and do all applicable related investigative/corrective actions; by doing all of the actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2658, dated February 22, 2007, except as provided by paragraphs (f)(1) and (f)(2) of this AD. Do all applicable related investigative/corrective actions before further flight. Repeat the inspections thereafter at the applicable interval specified in paragraph 1.E., “Compliance” of the service bulletin.

(1) Where the service bulletin specifies to contact Boeing for appropriate action, before further flight, do the action using a method approved in accordance with the procedures specified in paragraph (g) of this AD.

(2) Where the service bulletin specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.

Alternative Methods of Compliance (AMOCs)

(g)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on June 25, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.