AD 2014-08-11

This AD is effective June 3, 2014.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of June 3, 2014.

For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221.

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6440; fax: 425-917-6590; email: nancy.marsh@faa.gov.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2009-24-07, Amendment 39-16095 (74 FR 62231, November 27, 2009). AD 2009-24-07 applied to certain The Boeing Company Model 737-600, -700, -700C, and -800 series airplanes. The NPRM published in the Federal Register on August 13, 2013 (78 FR 49229). The NPRM was prompted by reports of corrosion protection damage to the forward trunnion pin on additional airplanes. The NPRM proposed to continue to require repetitive lubrications of the right and left main landing gear (MLG) forward trunnion pins. The NPRM also proposed to continue to require an inspection for discrepancies of the transition radius of the MLG forward trunnion pins, and corrective actions if necessary. For certain airplanes, the NPRM proposed to continue to require repetitive detailed inspections for discrepancies (including finish damage, corrosion, pitting, and base metal scratches) of the transition radius of the left and right MLG trunnion pins, and corrective action if necessary. Replacing or overhauling the trunnion pins would terminate the actions required by AD 2009-24-07. The NPRM proposed to add airplanes to the applicability of AD 2009-24-07. We are issuing this AD to prevent stress corrosion cracking of the forward trunnion pins, which could result in fracture of the pins and consequent collapse of the MLG.

We gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal (78 FR 49229, August 13, 2013) and the FAA's response to each comment.

Boeing stated that it concurs with the content of the NPRM (78 FR 49229, August 13, 2013).

Aviation Partners Boeing stated that the installation of winglets per STC ST00830SE ( http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/408E012E008616A7862578880060456C?OpenDocument&Highlight=st00830se) does not affect the accomplishment of the manufacturer's service instructions.

We have redesignated paragraph (c) of the NPRM (78 FR 49229, August 13, 2013) as paragraph (c)(1) of this AD, and added paragraph (c)(2) to this AD to state that installation of STC ST00830SE ( http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/408E012E008616A7862578880060456C?OpenDocument&Highlight=st00830se) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST00830SE is installed, a “change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17. For all other AMOC requests, the operator must request approval of an AMOC in accordance with the procedures specified in paragraph (l) of this AD.

Delta asked for clarification of the term “trunnion pins” as specified in the NPRM (78 FR 49229, August 13, 2013). Delta stated that throughout the preamble of the NPRM, the subject pins are referred to as “forward trunnion pins;” however, in paragraphs (h) and (i) of the NPRM, the location is omitted and the term “trunnion pins” is used. Delta noted that since forward and aft trunnion pins are installed, failing to identify the affected pin as a “forward trunnion pin” adds a potential for errors.

We agree that the term “trunnion pins” should be clarified to include the pin location. We have changed paragraphs (h) and (i) of this final rule to specify “forward trunnion pins.”

Delta asked that paragraph (g) of the NPRM (78 FR 49229, August 13, 2013) be changed to allow the use of Royco-11MS grease as an alternate to the BMS 3-33 grease specified in Boeing Special Attention Service Bulletin 737-32-1402, Revision 1, dated February 7, 2013. Delta stated that Royco-11MS is the standard grease used on Delta aircraft landing gear applications, and it would like to continue using this grease when lubricating the forward trunnion pins.

We do not agree to allow the use of an alternative type of grease. Approval of an operator's unique maintenance actions is dependent on its ability to provide acceptable data supporting the request. We would not provide such an approval to all operators via a change to the NPRM (78 FR 49229, August 13, 2013). However, we would consider this request for approval of unique maintenance practices in accordance with the procedures identified in paragraph (l) of this AD. We have made no change to this final rule in this regard.

Ryanair (RYR) asked that clarification be provided to reflect new information it received from Boeing. RYR stated that the intent of paragraphs (g) and (h) of the NPRM (78 FR 49229, August 13, 2013) appears to be to require that the 30-day repetitive lubrication task continue until all repetitive inspections are completed, as stated in Notes (a) and (b) of paragraph 1.E., “Compliance,” of Boeing Special Attention Service Bulletin 737-32-1402, Revision 1, dated February 7, 2013. RYR received correspondence from Boeing stating that the 30-day lubrication task is terminated after accomplishing the first in-situ detailed inspection. RYR recommends the information from Boeing be included in the NPRM.

RYR has correctly interpreted the requirements in paragraphs (g) and (h) of this AD. However, we find that further clarification is necessary. If certain discrepancies are found during the detailed inspection of the forward trunnion pins, replacing the affected trunnion pins terminates the repetitive requirements in this AD. If no discrepancies are found during the detailed inspection of the forward trunnion pins, an additional lubrication of the left and right MLG forward trunnion is required, which terminates the repetitive requirements in this AD. If certain other discrepancies are found during the detailed inspection of the forward trunnion pins, the lubrications and detailed inspections must be repeated until overhaul or replacement of the affected trunnion pins.

Additionally, Boeing did not provide any new information or data to the FAA, nor are we aware of any intention to revise its service information. However, under the provisions of paragraph (l) of this AD, we may consider requests for approval of an alternative method of compliance (AMOC) if sufficient data are submitted to substantiate that terminating the repetitive lubrications after doing the first detailed inspection would provide an acceptable level of safety. In light of these factors, we have made no change to this final rule.

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this AD with the changes described previously. We also determined that these changes will not increase the economic burden on any operator or increase the scope of this AD.

We estimate that this AD affects 431 airplanes of U.S. registry.

We have received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this AD.

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.

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Is not a “significant rule” under 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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by removing Airworthiness Directive (AD) 2009-24-07, Amendment 39-16095 (74 FR 62231, November 27, 2009), and adding the following new AD: