"2019-14-12 - The FAA is adopting an airworthiness directive (AD) for certain The Boeing Company Model 737-8 and 737-9 airplanes. This AD requires a maintenance records check to determine if any main slat track assembly has been removed, an inspection of the main slat track assemblies for a suspect lot number or a lot number that cannot be determined, and applicable on-condition actions. This AD was prompted by a report that certain main slat track assemblies were manufactured incorrectly and are affected by hydrogen embrittlement. The FAA is issuing this AD to address the unsafe condition on these products."
The FAA has received a report from Boeing indicating that 148 main slat track assemblies from a set of lot numbers were manufactured incorrectly and are affected by hydrogen embrittlement. Main slat track assemblies that are affected by hydrogen embrittlement have reduced strength. After reviewing information within the report provided from Boeing, the FAA determined on May 22, 2019, that this condition, if not addressed, could result in failure of main slat track assemblies, which could cause the slat to depart and potentially strike the airplane, resulting in injury to airplane occupants and/or preventing continued safe flight and landing.
Other Relevant Rulemaking
The FAA issued AD 2019-11-03, Amendment 39-19649 (84 FR 26743, June 10, 2019) (“AD 2019-11-03”), for certain The Boeing Company Model 737-700C, -800, and -900ER series airplanes. The FAA issued AD 2019-11-03 to address main slat track assemblies that have reduced strength due to hydrogen embrittlement. This condition, if not addressed, could result in failure of main slat track assemblies, which could cause the slat to depart and potentially strike the airplane, resulting in injury to airplane occupants and/or preventing continued safe flight and landing.
In the preamble of the final rule issuing AD 2019-11-03, the FAA stated that the identified unsafe condition also exists on Boeing Model 737-8 and 737-9 airplanes. The FAA also stated that Boeing was developing service information that would address the unsafe condition for these airplanes and that the FAA might consider additional rulemaking once that service information was developed, approved, and available. Boeing has since developed such service information and the FAA has determined that further rulemaking is indeed necessary.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Boeing Alert Requirements Bulletin 737-27A1311 RB, dated June 24, 2019. This service information describes procedures for a maintenance records check to determine if any main slat track assembly has been removed, an inspection of the main slat track assemblies for a suspect lot number or a lot number that cannot be determined, sending the inspection results to Boeing, and applicable on-condition actions. On-condition actions include replacing main slat track assemblies having a suspect lot number, or having a lot number that cannot be determined, with serviceable main slat track assemblies; shipping main slat track assemblies with suspect lot numbers or with lot numbers that cannot be determined to Boeing; and contacting Boeing to report if any main slat track assembly has been removed. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.
The FAA is issuing this AD because the agency 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.
This AD requires accomplishment of the actions identified in Boeing Alert Requirements Bulletin 737-27A1311 RB, dated June 24, 2019, described previously, except for any differences identified as exceptions in the regulatory text of this AD.
For information on the procedures and compliance times, see this service information at http://www.regulations.gov by searching for and locating Docket No. FAA-2019-0575.
Justification for Immediate Adoption and Determination of the Effective Date
Section 553(b)(3)(B) of the Administrative Procedure Act (APA) (5 U.S.C.) authorizes agencies to dispense with notice and comment procedures for rules when the agency, for “good cause,” finds that those procedures are “impracticable, unnecessary, or contrary to the public interest.” Under this section, an agency, upon finding good cause, may issue a final rule without seeking comment prior to the rulemaking. Similarly, Section 553(d) of the APA authorizes agencies to make rules effective in less than thirty days, upon a finding of good cause.
The discrepant parts are “rotable” in that they could be removed from the 737-8 and 737-9 airplanes that are the subject of this AD, and installed on 737 Next Gen (Boeing Model 737-600/-700/-800/-900) airplanes. The current shortage of nondiscrepant parts makes this removal and reinstallation more likely to happen. Also, these parts are not serialized, and have been marked in a manner that has proven to be impermanent. Thus, if a discrepant part were to be removed from a 737-8 or 737-9 airplane and installed on a 737 Next Gen airplane before all of the discrepant parts have been identified, it could expose the entire 737 Next Gen fleet to the unsafe condition, and likely require fleetwide inspections to find the discrepant parts.
The FAA therefore considers the prompt identification and removal of these parts from 737-8 and 737-9 airplanes to be an urgent safety issue. Accordingly, notice and opportunity for prior public comment are impracticable and contrary to the public interest pursuant to 5 U.S.C. 553(b)(3)(B). In addition, for the reasons stated above, the FAA finds that good cause exists pursuant to 5 U.S.C. 553(d) for making this amendment effective in less than 30 days.
Regulatory Flexibility Act (RFA)
The requirements of the RFA do not apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt a rule without prior notice and comment. Because the FAA has determined that it has good cause to adopt this rule without notice and comment, RFA analysis is not required.
This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment. However, the FAA invites you to send any written data, views, or arguments about this final rule. Send your comments to an address listed under the ADDRESSES section. Include the docket number FAA-2019-0575 and Product Identifier 2019-NM-113-AD at the beginning of your comments. The FAA specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this final rule. The FAA will consider all comments received by the closing date and may amend this final rule because of those comments.
The FAA will post all comments the agency receives, without change, to http://www.regulations.gov, including any personal information you provide. The FAA will also post a report summarizing each substantive verbal contact the agency receives about this final rule.