Airworthiness Directives; The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER 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 the products listed above. For certain airplanes, this proposed AD would require a one-time inspection for damage of the hydraulic actuator rod ends and actuator attach fittings on the thrust reversers, and repair or replacement if necessary. For all airplanes, this proposed AD also would require repetitive inspections for damage of the hydraulic actuator rod ends, attach bolts, and nuts; repetitive inspections for damage of fitting assemblies, wear spacers, and actuator attach fittings on the thrust reverser; repetitive measurements of the wear spacer; and corrective actions if necessary. This proposed AD was prompted by in-service damage of the attachment fittings for the thrust reverser actuator. We are proposing this AD to detect and correct such damage, which could result in actuator attach fitting failure, loss of the thrust reverser auto restow function, and consequent loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by May 6, 2011.

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: 202-493-2251.
• 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: Deliver to Mail address above 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; phone: 206-544-5000, extension 1; fax: 206-766-5680; e-mail: me.boecom@boeing.com; 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.

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 (phone: 800-647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Chris R. Parker, Aerospace Engineer, Propulsion Branch, ANM-140S, Seattle Aircraft Certification Office (ACO), FAA, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: 425-917-6496; fax: 425-917-6590; e-mail: Chris.R.Parker@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2011-0254; Directorate Identifier 2010-NM-180-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 indicating that the attachment fittings for the thrust reverser actuator have shown in-service wear damage. While in the stowed position, the actuator is locked and is in tension. The tensile load applied by the locking screw causes the hydraulic actuator rod end to rotate. As the hydraulic actuator rod end rotates, wear occurs to the bushings in the actuator attach fitting. The bushings continue to wear until there is contact directly between the hydraulic actuator rod end and the attach fitting. This condition, if not detected and corrected, could result in actuator attach fitting failure and loss of the thrust reverser auto restow function. Loss of the thrust reverser auto restow function removes one of the three primary levels of protection against an uncommanded thrust reverser deployment. An uncommanded thrust reverser deployment could result in loss of airplane control.

Relevant Service Information

We reviewed Boeing Special Attention Service Bulletin 737-78-1083, dated June 30, 2010. For Group 1 airplanes, this service bulletin specifies a one-time detailed inspection to detect damage (i.e., wear, cracks, nicks, dents, and scratches) of the hydraulic actuator rod ends and the actuator attach fittings on the right and left thrust reversers.

For airplanes on which damage is found on a hydraulic actuator rod end, this service bulletin specifies replacing of the hydraulic actuator rod end assembly with a new hydraulic actuator rod end assembly.

For airplanes on which no damage is found on an actuator attach fitting, this service bulletin specifies installing of a new spacer. For damage found on an actuator attach fitting that is within stated repair limits, this service bulletin specifies repairing the actuator attach fitting and installing a new spacer. For damage that exceeds the repair limits of the actuator attach fitting, this service bulletin specifies replacing the actuator attach fitting with a new actuator fitting.

For both Group 1 and Group 2 airplanes, this service bulletin describes procedures for repetitive inspections for damage (as specified in each inspection that follows), repetitive measurements, and corrective actions if necessary. The inspections and measurement include the following:

• A general visual inspection for cracks, nicks, dents, and scratches of the fitting assembly
• A detailed inspection for tears, holes, and disbonds of the wear spacer
• A measurement of the thickness of the wear spacer
• A detailed inspection for surface damage of the attach fitting
• A general visual inspection for damage (i.e. missing, cracked, or bent parts) of the rod end, attach bolt, and nut

The corrective actions include replacing spacers with new spacers, repairing attach fittings, replacing attach fittings with new attach fittings, replacing the rod end, attach bolt, and nuts with a new actuator rod end assembly.

FAA's Determination

We are proposing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and the Service Information.”

Differences Between the Proposed AD and the Service Information

Appendix A of Boeing Special Attention Service Bulletin 737-78-1083, dated June 30, 2010, specifies a general visual inspection for cracks, nicks, dents, and scratches of the fitting assembly. We have determined that this inspection is accomplished during the detailed inspections specified in Appendix A of Boeing Special Attention Service Bulletin 737-78-1083, dated June 30, 2010.

Appendix A of Boeing Special Attention Service Bulletin 737-78-1083, dated June 30, 2010, specifies to replace missing, cracked, and bent rod ends, attach bolts, and nuts, but does not specify replacement parts and how to replace the affected part. This proposed AD would require replacing missing, cracked, and bent rod ends, attach bolts, and nuts with new parts in accordance with a method approved by the FAA.

Costs of Compliance

We estimate that this proposed AD will affect 1,070 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

We estimate the following costs to do any necessary repairs or replacements that would be required based on the results of the proposed inspection. These on-condition costs are based on all the thrust reverser attachment fittings needing repair or replacement. We have no way of determining the number of aircraft that might need these repairs or replacements.

According to the manufacturer, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate.

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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

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.