E9-31431. Airworthiness Directives; The Boeing Company Model 777 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Model 777 airplanes. This proposed AD would require inspecting the bolt, nut, and downstop of the slat track assembly to determine if the bolt, nut, or stops are missing and to determine if the thread protrusion of the bolt from the nut is within specified limits and parts are correctly installed, and related investigative and corrective actions if necessary. For certain airplanes, this proposed AD would also require inspecting the slat cans at the outboard slat number 3 and 12 outboard main track locations for holes and wear damage, and corrective actions if necessary; and replacing the downstop hardware for the outboard slats number 3 and 12 outboard and inboard main track locations. This proposed AD results from a report of a hole in the inboard main track slat can for outboard slat number 12 on a Model 777 airplane. The hole was caused when the bolt securing the downstop migrated out of the fitting and contacted the slat can. We are proposing this AD to detect and correct damage to the outboard slat main track slat cans, which can allow fuel leakage into the fixed wing leading edge in excess of the capacity of the draining system. Excess fuel leakage could result in an uncontained fire.

DATES:

We must receive comments on this proposed AD by February 22, 2010.

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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152.

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:

Duong Tran, 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-2009-1249; Directorate Identifier 2009-NM-100-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

We have received a report of a hole in the inboard main track slat can for outboard slat number 12 on a Model 777 airplane. The hole was caused when the bolt securing the downstop migrated out of the fitting and contacted the slat can. Each outboard slat main track has a downstop attached to the aft end of the slat track assembly. The downstop consists of two fittings that are secured to the track with a bolt and nut. The main tracks travel through holes in the front spar web when the slat is retracted. In areas of the wing where fuel is stored, a slat can is installed on the fuel side of the spar to surround the main track and contain the fuel. It is believed that the locking element of the nut was not fully engaged, and the nut securing the bolt backed off and allowed the bolt to migrate out of the fitting and contact the slat can. In addition, in production it was discovered that a downstop was contacting the weld on a slat can at the outboard main track location on slat numbers 3 and 12. This contact could cause wear damage and eventually a hole in the slat can. This condition, if not corrected, could result in fuel leakage into the fixed wing leading edge in excess of the capacity of the draining system. Fuel leakage could result in an uncontained fire.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009. The service bulletin describes procedures for doing a detailed inspection of the slat main track stop hardware to determine if the bolt, nut, or stops are missing and to determine if the thread protrusion of the bolt from the nut is within specified limits. For airplanes on which hardware is missing or the thread protrusion is not within limits, the service bulletin describes procedures for doing applicable related investigative and corrective actions. These related investigative actions include measuring torque of the nuts of the slat main track stop hardware, and doing a detailed inspection of the slat can inside of the slat can for holes and gouges. The corrective actions include repairing or replacing the slat can and replacing the slat main track stop hardware.

The service bulletin also describes procedures for Group 2 airplanes for doing a detailed inspection of the slat cans at the outboard slat number 3 and 12 outboard main track locations for holes and wear damage, and corrective actions if necessary; and for replacing the downstop hardware for the outboard slats number 3 and 12 outboard and inboard main track locations. The corrective actions include replacing the slat main track stop hardware, and repairing or replacing the slat can.

The service bulletin specifies that the compliance time for the detailed inspections and the replacement is within 6 months after the issue date of the service bulletin. The compliance times for the related investigative actions range between before further flight and within 1,125 days or 6,000 flight cycles after the issue date of the service bulletin (whichever occurs first), depending on whether hardware is missing or whether damage is within the specified limits. The compliance times for the corrective actions range between before further flight and within 1,125 days after wear damage is found, depending on the severity of the damage.

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 these same type designs. This proposed AD would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

We estimate that this proposed AD would affect 129 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Table—Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per product	Number of U.S.- registered airplanes	Fleet cost
Inspection for Group 1 airplanes	39	$80	$0	$3,120 per inspection cycle	127	$396,240 per inspection cycle.
Inspection for Group 2 airplanes	55	80	0	$4,400 per inspection cycle	2	$8,800 per inspection cycle.
Replacement for Group 2 airplanes	8	80	9,267	$9,907	2	$19,814.

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
• Incorporation by reference
• 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:

The Boeing Company: Docket No. FAA-2009-1249; Directorate Identifier 2009-NM-100-AD.

Comments Due Date

(a) We must receive comments by February 22, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to The Boeing Company Model 777-200, -200LR, -300, and -300ER airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009.

Subject

(d) Air Transport Association (ATA) of America Code 57: Wings.

Unsafe Condition

(e) This AD results from a report of a hole in the inboard main track slat can for outboard slat number 12 on a Model 777 airplane. The Federal Aviation Administration is issuing this AD to detect and correct damage to the outboard slat main track slat cans, which can allow fuel leakage into the fixed wing leading edge in excess of the capacity of the draining system. Excess fuel leakage could result in an uncontained fire.

Compliance

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

Inspect the Slat Track Stop Hardware and Measure the Torque of the Slat Main Track Stop Hardware

(g) At the applicable time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009, except as required by paragraph (h) of this AD: Do the applicable actions specified in paragraphs (g)(1) and (g)(2) of this AD.

(1) For all airplanes: Do a detailed inspection of the slat main track stop hardware to determine if the bolt, nut, or stops are missing and to determine if the thread protrusion of the bolt from the nut is within specified limits, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009. Do all applicable related investigative and corrective actions at the applicable time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009, except as required by paragraph (h) of this AD.

(2) For airplanes identified as Group 2 airplanes in Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009: Do a detailed inspection of the slat cans at the outboard slat number 3 and 12 outboard main track locations for holes and wear damage and all applicable corrective actions, and replace the downstop hardware for the outboard slats number 3 and 12 outboard and inboard main track locations. Do all applicable corrective actions at the applicable time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009.

Exception to the Service Bulletin

(h) Where Boeing Alert Service Bulletin 777-57A0064, dated March 26, 2009, 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)

(i)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Duong Tran, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Or, e-mail information to [e-mail].

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

(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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that 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 December 23, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.