Discussion \n\n\n\tThe EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2020-0104R1 dated January 28, 2021 (EASA AD 2020-0104R1) (referred to after this as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for all Airbus SAS Model A318-111, A318-112, A318-121, and A318-122 airplanes; Model A319-111, A319-112, A319-113, A319-114, A319-115, A319-131, A319-132, and A319-133 airplanes; Model A320-211, A320-212, A320-214, A320-216, A320-231, A320-232, and A320-233 airplanes; and Model A321-111, A321-112, A321-131, A321-211, A321-212, A321-213, A321-231, and A321-232 airplanes. \n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Airbus SAS Model A318 series airplanes; Model A319-111, A319-112, A319-113, A319-114, A319-115, A319-131, A319-132, and A319-133 airplanes; Model A320-211, A320-212, A320-214, A320-216, A320-231, A320-232, and A320-233 airplanes; and Model A321-111, A321-112, A321-131, A321-211, A321-212, A321-213, A321-231, and A321-232 airplanes. The NPRM published in the Federal Register on October 15, 2020 (85 FR 65282). The NPRM was prompted by reports that certain oxygen supply solenoid valves are a potential source of increased flow resistance within the flightcrew oxygen system. The NPRM proposed to require a detailed inspection (flow test) of certain solenoid valves, and replacement if necessary, as specified in EASA AD 2020-0104R1. \n\tThe FAA is issuing this AD to address increased flow resistance within the flightcrew oxygen system, which could lead to a reduced flow of oxygen supply to the flightcrew oxygen masks, and in combination with in-flight depressurization, smoke in the flight deck, or a smoke evacuation procedure, could lead to flightcrew hypoxia and loss of useful consciousness, resulting in loss of control of the airplane. See the MCAI for additional background information. \n\nRevised EASA AD \n\n\n\tIn the NPRM, the FAA referred to EASA AD 2020-0104, dated May 7, 2020 (EASA AD 2020-0104). Since the NPRM was issued, EASA issued AD 2020-0104R1, which clarifies that certain solenoid valves are no longer considered affected parts. \n\tThe agency determined that no additional work is required for airplanes \n\n((Page 21921)) \n\nthat have accomplished the actions as required by EASA AD 2020-0104. Therefore, the agency has revised all applicable sections in this final rule to also specify EASA AD 2020-0104R1. \n\nComments \n\n\n\tThe FAA gave the public the opportunity to participate in developing this final rule. The following presents the comments received on the NPRM and the FAA's response to each comment. \n\nSupport for the NPRM \n\n\n\tThe Air Line Pilots Association, International (ALPA) stated that it supports the NPRM. \n\nRequest To Allow Use of Additional Service Information \n\n\n\tAmerican Airlines (AA) requested that operators be allowed to use the deviation provided in an Airbus technical adaptation for a certain solenoid valve test. The operator noted that there is a discrepancy in the Airbus service bulletin specified in EASA AD 2020-0104. The commenter explained that one of the required for compliance (RC) paragraphs in the service bulletin states that a test of the solenoid valve is required, no matter the result of the three masks flow test, but a flowchart in that service bulletin does not indicate that this test is required if the three masks flow test was successful. The commenter stated that it contacted Airbus regarding this issue and Airbus confirmed that there is an error and provided a Design Organization Approval (DOA) approved technical adaptation to address that error. \n\tThe FAA agrees with the commenter's request for the reasons provided. The FAA has added paragraph (h)(4) to this AD to allow the use of Airbus Technical Adaptation 80843604/008/2020, Issue 1, dated November 3, 2020.Request To Include Requirement for Part Marking \n\n\n\tUnited Air Lines (UAL) requested that affected parts that were inspected and passed the three masks flow test be marked. The commenter explained that this would assist operators in easily identifying an affected part that has been inspected and passed the three masks flow test. The commenter stated that this would prevent the part from being tied to a specific airplane and would allow installation of that part on another airplane. \n\tThe FAA disagrees with the commenter's request. The FAA conferred with EASA and EASA responded that allowing an affected part to become a rotable part had been discussed during development of its original proposed AD. It was determined that, because of the potential differences in the oxygen system architecture in the configuration of different airplanes, a part that successfully passed the three masks flow test on one airplane does not guarantee that an air flow deficit would not exist if that part was moved to another airplane with a different oxygen system configuration. In addition, Airbus recommended that a pass/fail label not be applied to tested valves to avoid complications in tracking parts based on the tested oxygen system configuration. For these reasons, the FAA finds that no change to this AD is necessary in regard to this issue. \n\nRequest To Clarify Parts Installation Paragraph \n\n\n\tUAL stated that it objected to paragraph (3), Part(s) Installation, of EASA AD 2020-0104 that was referred to in the proposed AD. The commenter stated that, in the interest of safety, an affected part should not be allowed to be installed on an airplane. The FAA infers that the commenter is requesting that the proposed AD be revised to include a Parts Installation Prohibition paragraph to prohibit operators from installing an affected part on an airplane. \n\tThe FAA does not agree with the commenter's request. The FAA has determined that if, before the next flight after installation onan airplane, an affected part passes the required flow test, the unsafe condition identified in this AD has been addressed and there is not a safety of flight issue. The FAA has not revised this AD in regard to this issue. \n\nRequest To Omit Duplicate Test \n\n\n\tUAL requested that the order of certain actions identified as RC in the Airbus SAS service bulletin specified in EASA AD 2020-0104 be changed. The commenter suggested that, instead of waiting until after the failure of a test to check that the oxygen storage cylinder is fully open and then doing the test again, the check of the oxygen cylinder should be part of the test preparation. The commenter explained that this would preclude the repetition of the test. \n\tThe FAA disagrees with the commenter's request. The FAA conferred with EASA and it is presumed that the oxygen cylinder is fully open prior to starting the test. In addition, the majority of test reports provided by operators to Airbus and EASA did not identify any flow blockage. Therefore, adding the step to ensure that the oxygen cylinder is fully open would increase the work involved to accomplish each test versus doing only a check for the sole purpose of demonstrating compliance with an AD. Neither Airbus nor EASA recommend changing the order of the actions identified as RC in the Airbus SAS service bulletin and the FAA concurs. However, the FAA does not have any objection if the commenter or any operator includes a step in the test preparation to ensure that the oxygen cylinder is fully open to avoid the duplicative test identified by the commenter. The FAA has not revised this AD in regard to this issue. \n\nConclusion \n\n\n\tThe FAA reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule with the changes described previously and minor editorial changes. The FAA has determined that these minor changes: \n\tAre consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM. \n\tThe FAA also determined that these changes will not increase the economic burden on any operator or increase the scope of this final rule. \n\nRelated Service Information Under 1 CFR Part 51 \n\n\n\tEASA ADs 2020-0104 and 2020-0104R1 describe procedures for doing a detailed inspection (flow test) of certain solenoid valves using the flightcrew oxygen masks and replacing any solenoid valve that fails the flow test with a serviceable part. These documents are distinct since AD 2020-0104R1 clarifies that certain solenoid valves are no longer considered affected parts. \n\tAirbus SAS has issued Technical Adaptation 80843604/008/2020, Issue 1, dated November 3, 2020, which specifies that, when a solenoid valve successfully passes the three masks flow test, operators do not need to do the test specified in paragraph 3.E.(1) of the AccomplishmentInstructions of the Airbus SAS service information specified in EASA ADs 2020-0104 and 2020-0104R1. \n\tThis material 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. \n\n((Page 21922)) \n\nCosts of Compliance \n\n\n\tThe FAA estimates that this AD affects 1,100 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: \n\n\n\tEstimated Costs for Required Actions ---------------------------------------------------------------------------------------------------------------- \n\tCost per Cost on U.S. \n\tLabor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- 3 work-hours x $85 per hour = $255........................... $0 $255 $280,500 ---------------------------------------------------------------------------------------------------------------- \n\n\n\tThe FAA estimates the following costs to do any necessary on- condition action that would be required based on the results of any required actions. The FAA has no way of determining the number of aircraft that might need this on-condition action: \n\n\n\tEstimated Costs of On-Condition Action ------------------------------------------------------------------------ \n\tCost per \n\tLabor cost Parts cost product ------------------------------------------------------------------------ 1 work-hour x $85 per hour = $85...... $ * $85 ------------------------------------------------------------------------ \n* The FAA has received no definitive data that would enable the agency\n\n\tto provide parts cost estimates for the on-condition replacement \n\tspecified in this AD. \n\n\n\tAccording to the manufacturer, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators. The FAA does not control warranty coverage for affected operators. As a result, the FAA has included all known costs in our cost estimate. \n\nAuthority for This Rulemaking \n\n\n\tTitle 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. \n\tThe FAA is 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 islikely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\n\tThis 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. \n\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a ''significant regulatory action'' under Executive Order 12866, \n\t(2) Will not affect intrastate aviation in Alaska, and \n\t(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. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.