Voglio sapere a riguardo di…

Federal Register / Vol. 86, No. 136 / Tuesday, July 20, 2021 / Rules and Regulations Effect of Certain Installation Procedures on Accomplishment of AD
Requirements As previously noted, the FAA issued AD 20152111, applicable to certain Model 737100, 200, 200C, 300, 400, 500, 600, 700, 700C, 800, 900, and 900ER series airplanes. AD
20152111 requires, among other actions, the installation of a redundant cabin altitude pressure switch in accordance with specified Boeing service information. The FAA has since approved numerous supplemental type certificates STCs and other means for installing the redundant pressure switch. As a result of its oversight of these newly-installed switches, the FAA
has determined that use of approved maintenance procedures for the cabin altitude pressure switch functional test other than those specified in the task cards identified in Boeing Multi Operator Message MOMMOM21
029201B, dated June 23, 2021, is acceptable for the functional test;
therefore, those other procedures do not require approval of an alternative method of compliance AMOC.

khammond on DSKJM1Z7X2PROD with RULES

Differences Between This AD and the Service Information Although Boeing Multi Operator Message MOMMOM21029201B, dated June 23, 2021, affects all 737CL
airplanes the 737 Classics include Model 737100, 200, 200C, 300, 400, and 500, Boeing did not send the MOM to Model 737100, 200 and 200C operators. Additionally, Boeing did not reference procedures for performing the cabin altitude pressure switch functional test for Model 737
100, 200, and 200C series airplanes.
There are no Model 737100 series airplanes operating worldwide;
however, the applicability of this AD
includes those airplanes in the event any of those airplanes are returned to service in the U.S. The FAA has also included Model 737200 and 200C
series airplanes in the applicability of this AD. Furthermore, the FAA
requested that Boeing make the service information available to Model 737200
and 200C operators. Boeing Model 737200 and 200C operators may reference 737200 Airplane Maintenance Manual AMM 213311/
501 for additional guidance on performing the cabin altitude pressure switch functional test.
Boeing Multi Operator Message MOMMOM21029201B, dated June 23, 2021, uses permissive language, such as recommends and requesting, in its Functional Test Requirements and Reporting
VerDate Sep<11>2014

15:59 Jul 19, 2021

Jkt 253001

Requirements sections. However, the regulatory text in paragraphs g and h of this AD makes the language in those sections mandatory unless an exception in paragraph j of this AD applies.
Boeing Multi Operator Message MOMMOM21029201B, dated June 23, 2021, recommends returning failed pressure switches to the switch manufacturer. Although the FAA also recommends that operators return failed pressure switches in order to provide the switch manufacturer with additional data related to the unsafe condition, this AD does not require that action.
Although Boeing Multi Operator Message MOMMOM21029201B, dated June 23, 2021, identifies specific AMM task cards for use in accomplishing the functional test, paragraph j1 of this AD clarifies that any approved maintenance procedures may be used for the functional test. This provides the operator an option to use the AMM task card or any approved maintenance procedure for the functional test without needing to request an AMOC.
Boeing Multi Operator Message MOMMOM21029201B, dated June 23, 2021, specifies certain on-condition actions, including an additional step while performing the functional test on the switch by increasing the altitude setting on the switch to an altitude of up to 20,000 feet if the cabin altitude warning does not activate by 11,000 feet during the initial functional test. The service information specifies repeating the functional test at intervals, but does not explicitly state that the on-condition additional functional testing is limited to the initial functional test only.
Paragraph j3 of this AD requires the on-condition additional functional test step of increasing the altitude setting to 20,000 feet only during the initial functional test if applicable.
Although Boeing Multi Operator Message MOMMOM21029201B, dated June 23, 2021, specifies that failed switches be replaced with new or serviceable switches, this AD requires replacement with serviceable switches, which include any switches that are eligible for installation. This is to ensure that any installed switch is serviceable.
Interim Action The FAA considers this AD to be an interim action. The reporting that is required by this AD will enable the airplane manufacturer to obtain better insight into the nature, cause, and extent of the switch failures, and eventually to develop final action to address the unsafe condition. Once final
PO 00000

Frm 00007

Fmt 4700

Sfmt 4700

38215

action has been identified, the FAA
might consider further rulemaking.
Justification for Immediate Adoption and Determination of the Effective Date Section 553b3B of the Administrative Procedure Act APA 5
U.S.C. 551 et seq. 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 providing notice and seeking comment prior to issuance.
Further, section 553d of the APA
authorizes agencies to make rules effective in less than thirty days, upon a finding of good cause.
An unsafe condition exists that requires the immediate adoption of this AD without providing an opportunity for public comments prior to adoption.
The FAA has found that the risk to the flying public justifies forgoing notice and comment prior to adoption of this rule because, as previously noted, the unexpectedly high rate of latent failure, of both pressure switches on the same airplane, could result in the cabin altitude warning system not activating if the cabin altitude exceeds 10,000 feet, resulting in hypoxia of the flightcrew, and loss of control of the airplane.
Accordingly, notice and opportunity for prior public comment are impracticable and contrary to the public interest pursuant to 5 U.S.C. 553b3B.
In addition, the FAA finds that good cause exists pursuant to 5 U.S.C. 553d for making this amendment effective in less than 30 days, for the same reasons the FAA found good cause to forgo notice and comment.
Comments Invited The FAA invites you to send any written data, views, or arguments about this final rule. Send your comments to an address listed under ADDRESSES.
Include Docket No. FAA20210561
and Project Identifier AD202100623
T at the beginning of your comments.
The most helpful comments reference a specific portion of the final rule, explain the reason for any recommended change, and include supporting data.
The FAA will consider all comments received by the closing date and may amend this final rule because of those comments.
Except for Confidential Business Information CBI as described in the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to https

E:FRFM20JYR1.SGM

20JYR1