E8-11565. Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR series airplanes. This proposed AD would require repetitive inspections for cracks or fractures of the forward end attachment and the forward lower flange of the flap tracks of the trailing edge flaps, and corrective actions if necessary. For certain airplanes, this proposed AD would also require modifying the fail-safe links of the main carriage. This proposed AD results from a detailed structural analysis of the flap attach structural and fail-safe components, accomplished as a result of a dynamic stability and control analysis, which could not demonstrate continued safe flight and landing of the airplane after the loss of a trailing edge flap. We are proposing this AD to detect and correct cracks or fractures of the primary structural and fail-safe load paths of the inboard and outboard trailing edge flaps, which could result in the loss of a flap during takeoff or landing, reducing flightcrew ability to maintain the safe flight and landing of the airplane.

DATES:

We must receive comments on this proposed AD by July 7, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• 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.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Gary Oltman, 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 send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2008-0590; Directorate Identifier 2008-NM-057-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

A detailed structural analysis of the flap attach structural and fail-safe components, accomplished as a result of a dynamic stability and control analysis, could not demonstrate continued safe flight and landing of the airplane after the loss of a trailing edge flap. This structural analysis showed that additional inspections and modifications should be accomplished to prevent the loss of a flap. For components where there is a fail-safe load path, the inspections were based on finding a fractured component within the fatigue life of the fail-safe component of the load path. For the main carriage fail-safe link load path, the analysis showed the components were not adequate to retain the flap in the case of a fracture of the carriage. These conditions, if not corrected, could result in the loss of a flap during takeoff or landing, reducing flightcrew ability to maintain the safe flight and landing of the airplane.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-57A2323, dated February 21, 2008. For all airplanes, the service bulletin describes procedures for repetitive general visual inspections for cracks or fractures of the forward end attachment of the flap tracks, fuse pin, and support fitting; repetitive detailed inspections for cracks or fractures of the forward lower flange of the flap tracks; and corrective actions if necessary. The corrective actions include replacing the flap track and the fail-safe strap if any crack or fracture is found in a flap track; replacing the fuse pin and fail-safe strap if any crack or fracture is found in a fuse pin; and replacing the support fitting if any crack or fracture is found in a support fitting. If no cracks are found, the general visual inspection is repeated during inspection of the flap track forward attachment, and after each replacement is done. For Groups 1 through 3 airplanes, the service bulletin describes procedures for modifying the fail-safe links of the main carriage by replacing the links, pins, and attachment hardware. The service bulletin also recommends contacting Boeing for repair data if a fractured support fitting is found.

The compliance time for the general visual inspection is within 6,000 total flight cycles on the flap track since new, or within 750 flight cycles, whichever occurs later. If no crack or fracture is found, the inspection is repeated at intervals not to exceed 750 flight cycles.

The compliance time for the detailed inspection is within 20,000 total flight cycles on the flap track since new, or within 1,500 flight cycles, whichever occurs later. If no crack or fracture is found, the inspection is repeated at intervals not to exceed 1,500 flight cycles.

The compliance time for modifying the fail-safe links of the main carriage for Groups 1 through 3 airplanes is within 24 months after the date on the service bulletin.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the Proposed AD and Service Information.”

Difference Between the Proposed AD and Service Information

The alert service bulletin specifies to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing 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.

Costs of Compliance

We estimate that this proposed AD would affect 190 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per product	Number of U.S.-registered airplanes	Fleet cost
Part 1: Inspections	4	$80	$0	$320, per inspection cycle	190	$60,800, per inspection cycle.
Part 3: Inspections	4	80	$0	$320, per inspection cycle	190	$60,800, per inspection cycle.
Part 2: Modification for Groups 1-3 airplanes	Between 3 and 7	80	Between $212 and $7,934	Between $452 and $8,494	182	Between $82,264 and $1,545,908.

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 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 this 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

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 FAA amends § 39.13 by adding the following new AD:

Boeing: Docket No. FAA-2008-0590; Directorate Identifier 2008-NM-057-AD.

Comments Due Date

(a) We must receive comments by July 7, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from a detailed structural analysis of the flap attach structural and fail-safe components accomplished as a result of a dynamic stability and control analysis, which could not demonstrate continued safe flight and landing of the airplane after the loss of a trailing edge flap. We are issuing this AD to detect and correct cracks or fractures of the primary structural and fail-safe load paths of the inboard and outboard trailing edge flaps, which could result in the loss of a flap during takeoff or landing, reducing flightcrew ability to maintain the safe flight and landing of the airplane.

Compliance

(e) Comply with this AD within the compliance times specified, unless already done.

Repetitive Inspections/Corrective Actions

(f) For all airplanes: Except as provided by paragraph (h) of this AD; at the applicable times specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-57A2323, dated February 21, 2008, inspect for cracks or fractures of the forward end attachment and the forward lower flange of the flap tracks of the trailing edge flaps by doing all the actions specified in Parts 1 and 3 of the Accomplishment Instructions of the service bulletin; except as provided by paragraph (i) of this AD. Do all applicable corrective actions before further flight. Repeat the applicable inspection at the applicable time specified in paragraph 1.E. of the service bulletin.

Modification of Fail Safe Links of Main Carriage

(g) For Groups 1, 2, and 3 airplanes: Within 24 months after the effective date of this AD, replace the fail-safe links, pins, and attachment hardware in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-57A2323, dated February 21, 2008.

Exception to Compliance Times

(h) Where Boeing Alert Service Bulletin 747-57A2323, dated February 21, 2008, specifies counting the compliance time from “* * * the date on this service bulletin,” this AD requires counting the compliance time from the effective date of this AD.

Exception to Corrective Actions

(i) If any fractured support fitting is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-57A2323, dated February 21, 2008, specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (j) of this AD.

Alternative Methods of Compliance (AMOCs)

(j)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Gary Oltman, Aerospace Engineer, Airframe Branch, ANM-120S, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]; has the authority to approve AMOCs for this AD, if requested using 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 May 16, 2008.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.