preamble attached >>>
ADs updated daily at www.Tdata.com
2022-24-09 THE BOEING COMPANY: Amendment 39-22249; Docket No. FAA-2022-0588; Project Identifier AD-2022-00114-T.
(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective January 26, 2023.

(b) AFFECTED ADS

    This AD replaces AD 2021-14-20,  Amendment 39-21647 (86 FR 38214, July
    20, 2021) (AD 2021-14-20).

(c) APPLICABILITY

    This AD applies to all The Boeing Company  Model 737-100, -200, -200C,
    -300, -400, -500, -600, -700, -700C, -800, -900 and -900ER series air-
    planes, and Model 737-8, 737-9 and 737-8200 airplanes, certificated in
    any category.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 21, Air conditioning.

(e) UNSAFE CONDITION

    This  AD was  prompted  by  reports of  latent failures  of the  cabin
    altitude pressure switches, and  the determination that using  certain
    adapters while performing a functional test may lead to false failures
    of the cabin altitude pressure switches. The FAA is issuing this AD to
    address the unexpectedly high rate of latent failure of both  pressure
    switches  on  the  same  airplane, which  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.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) REPETITIVE FUNCTIONAL TESTS

(1) At the latest of the times  specified in paragraphs (g)(1)(i)  through
    (iii) of  this AD,  perform a  functional test  of the  cabin altitude
    pressure switches  having part  number 214C50-2,  using an  adapter as
    specified in figure 1  to paragraph (g) of  this AD, or an  equivalent
    adapter, and matching  hose to connect  to the cabin  altitude warning
    switch.  Repeat the  functional test  thereafter at  intervals not  to
    exceed 2,000 flight hours. If,  during any functional test, any  cabin
    altitude pressure switch fails to  activate at an altitude of  between
    9,000 and 11,000 feet, replace the switch before further flight.

(i) Within 2,000 flight hours  since the last functional test of the cabin
    altitude pressure switches.

(ii) Prior  to  the  accumulation of 2,000 total flight hours  on the air-
     plane.

(iii) Within 90 days after the effective date of this AD.

(2) Adapters are considered  to  be  equivalent as long as the mating side
    with the switch meets the specifications in either paragraph (g)(2)(i)
    or (ii) of this AD:

(i) Greater than  or  equal to 0.265 inch (0.673 cm) X 7/16-20-UNJF-3A and
    less than  or equal to 0.438 inch (1.113 cm) X 7/16-20-UNJF-3A for the
    flareless end; or

(ii) Less than  or  equal to 0.5 inch (1.27 cm) total with greater than or
     equal  to  0.265 inch  (0.673 cm) X 7/16-20-UNJF-3A  thread  for  AN4
     flared end.

        FIGURE 1 TO PARAGRAPH (G) OF THIS AD  FUNCTIONAL TEST ADAPTERS
    ______________________________________________________________________
    Use one of the following adapters, or an equivalent adapter and match-
    ing hose to connect to the cabin altitude warning switch:

    (1) SAE J514 part number  (P/N) 070220 90 Degree Straight Thread Elbow
        and appropriate sized O-ring (Preferred).

    - Use a Barfield Pitot Hose, or equivalent 25 feet (7.62 m) to 40 feet
      (12.19 m) long hose, with #4 AN fitting to the adapter and quick dis
      -connect (if applicable) to the air data test set.

    - Make sure that the flat side  of  the  adapter is connected with the
      cabin altitude warning switch.

    NOTE: Do not connect the flared side of the adapter with the cabin al-
    titude warning switch. Connecting the flared side of the adapter  with
    the cabin altitude  warning switch may  bottom out the  cabin altitude
    warning switch, resulting in false test results.

    (2) SAE J514 P/N 070320 45 Degree Straight Thread Elbow  and appropri-
        ate sized O-ring (Preferred).

    - Use a Barfield Pitot Hose, or equivalent 25 feet (7.62 m) to 40 feet
      (12.19 m) long hose, with #4 AN fitting to the adapter and quick dis
      -connect (if applicable) to the air data test set.

    - Make sure that the flat side  of the adapter  is connected  with the
      cabin altitude warning switch.

    NOTE: Do not connect the flared side of the adapter with the cabin al-
    titude warning switch. Connecting the flared side of the adapter  with
    the cabin altitude  warning switch may  bottom out the  cabin altitude
    warning switch, resulting in false test results.

    (3) SAE J514 P/N 070120 Straight Thread Connector Short  and appropri-
        ate sized O-ring (Preferred).

    - Use a Barfield Pitot Hose, or equivalent 25 feet (7.62 m) to 40 feet
      (12.19 m) long hose, with #4 AN fitting to the adapter and quick dis
      -connect (if applicable) to the air data test set.

    - Make sure that the flat side  of the adapter  is connected  with the
      cabin altitude warning switch.

    NOTE: Do not connect the flared side of the adapter with the cabin al-
    titude warning switch. Connecting the flared side of the adapter  with
    the cabin altitude  warning switch may  bottom out the  cabin altitude
    warning switch, resulting in false test results.

    (4) AS21900-4 (or MS21900-4) Flareless Tube to Flared Tube Adapter and
        appropriate sized O-ring (Preferred).

    - Use a Barfield Pitot Hose, or equivalent 25 feet (7.62 m) to 40 feet
      (12.19 m) long hose, with #4 AN fitting to the adapter and quick dis
      -connect (if applicable) to the air data test set.

    - Make sure that the flat side  of the adapter  is connected  with the
      cabin altitude warning switch.

    NOTE: Do not connect the flared side of the adapter with the cabin al-
    titude warning switch. Connecting the flared side of the adapter  with
    the cabin altitude  warning switch may  bottom out the  cabin altitude
    warning switch, resulting in false test results.

    (5) P/N JUD321 Hose Fitting with MS28778-4 O-ring (Eaton Aerospace LLC
        Bethel, CT 02750) (Preferred).

    - Use a Barfield Pitot Hose, or equivalent 25 feet (7.62 m) to 40 feet
      (12.19 m) long hose, with #4 AN fitting to the adapter and quick dis
      -connect (if applicable) to the air data test set.

    (6) AN807-4D (or AS5180D04 or AS5180W04) Tube to Hose Adapter, AN924-4
        nut and appropriate sized O-ring  (on  the  mating  side  with the
        switch) and spacer or washers (Alternate).

    NOTE: This adapter  can be used if the steps below  are carefully fol-
    lowed. This adapter is not preferred because if the AN924-4 nut is not
    connected  carefully as  recommended below,  this may  bottom out  the
    cabin altitude warning switch, resulting in false test results.

    - Use a Barfield Pitot Hose, or equivalent 25 feet (7.62 m) to 40 feet
      (12.19 m) long hose,  with  quick disconnect  (if applicable) to the
      air data test set.

    - Make sure that the thread length, including fitting end after the in
      -stallation of AN924-4 nut and appropriate sized 7/16 spacer or wash
      -ers, is less than 0.5 inch (1.270 cm) to avoid false test results.
    ______________________________________________________________________

Note 1 to paragraph (g): Additional guidance for performing the functional
test required by paragraph (g)  of this AD can be found  in Boeing 737-200
Aircraft Maintenance Manual (AMM) 21-33-11/501, Boeing 737-300/400/500/600
/700/800/900/7/8/8200/9  AMM 21-33-00/501,  737CL AMM TASK CARD 31-026-01-
01, 737CL AMM TASK CARD 31-010-01-01, 737NG AMM TASK CARD 31-020-00-01 and
737MAX AMM TASK CARD 31-020-00-01,  and  other approved maintenance proce-
dures.

(h) MINIMUM EQUIPMENT LIST (MEL) PROVISIONS

    If any cabin altitude warning switch fails  any functional test as re-
    quired by this AD,  the airplane  may be operated  as specified in the
    operator's existing FAA-approved MEL, provided provisions that specify
    operating the airplane  at  a  flight altitude at or below 10,000 feet
    mean sea level  (MSL)  with the cabin altitude warning system inopera-
    tive are included in the operator's existing FAA-approved MEL.

(i) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The  Manager,  Seattle ACO Branch,  FAA,  has the authority to approve
    AMOCs for this AD, if requested  using the procedures found in 14  CFR
    39.19. In  accordance with  14 CFR  39.19, send  your request  to your
    principal  inspector  or  responsible  Flight  Standards  Office,   as
    appropriate. If  sending information  directly to  the manager  of the
    certification  office,  send  it  to  the  attention  of  the   person
    identified in paragraph (j)(1) of this AD.  Information may be emailed
    to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking a principal inspector,  the manager of the respon-
    sible Flight Standards Office.

(3) An AMOC that provides  an acceptable level  of safety  may be used for
    any repair, modification, or alteration  required by this AD if  it is
    approved by The Boeing Company Organization Designation  Authorization
    (ODA) that  has been  authorized by  the Manager,  Seattle ACO Branch,
    FAA,  to  make those  findings.  To be  approved,  the repair  method,
    modification  deviation,  or   alteration  deviation  must   meet  the
    certification  basis   of  the   airplane,  and   the  approval   must
    specifically refer to this AD.

(j) RELATED INFORMATION

(1) For more information about this AD,  contact  Nicole Tsang,  Aerospace
    Engineer, Cabin Safety and Environmental Systems Section, FAA, Seattle
    ACO Branch, 2200 South 216th St, Des Moines, WA 98198; phone: 206-231-
    3959; email: Nicole.S.Tsang@faa.gov.

(2) For service information identified in this AD that is not incorporated
    by reference, contact Boeing Commercial Airplanes, Attention: Contrac-
    tual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal
    Beach, CA 90740-5600; telephone 562-797-1717; website myboeingfleet.
    com.

(k) MATERIAL INCORPORATED BY REFERENCE

    None.

Issued on December 2, 2022.  Christina Underwood, Acting Director, Compli-
ance & Airworthiness Division, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT: Nicole Tsang,  Aerospace Engineer,  Cabin
Safety and Environmental Systems Section,  FAA,  Seattle ACO Branch,  2200
South 216th St., Des Moines, WA 98198; phone: 206-231-3959; email: Nicole.
S.Tsang@faa.gov.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0588; Project Identifier AD-2022-00114-T;
Amendment 39-22249; AD 2022-24-09]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2021-14-
20, which applied to all The Boeing Company Model 737 airplanes. AD
2021-14-20 required repetitive functional tests of the cabin altitude
pressure switches, and on-condition actions, including replacement, if
necessary. AD 2021-14-20 also required reporting test results. This AD
was prompted by data collected from the reports required by AD 2021-14-
20, which revealed that the switches were subject to false test
failures due to lack of clear instructions for setup of the test
adapters during the functional tests. This AD retains the repetitive
functional tests and on-condition actions, and specifies certain
adapter requirements for the functional tests. The FAA is issuing this
AD to address the unsafe condition on these products.

DATES: This AD is effective January 26, 2023.

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2022-0588; or in person at Docket Operations between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD
docket contains this final rule, any comments received, and other
information. The address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Nicole Tsang, Aerospace Engineer,
Cabin Safety and Environmental Systems Section, FAA, Seattle ACO
Branch, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-
3959; email: Nicole.S.Tsang@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2021-14-20, Amendment 39-21647 (86 FR
38214, July 20, 2021) (AD 2021-14-20). AD 2021-14-20 applied to all The
Boeing Company Model 737 airplanes. The NPRM published in the Federal
Register on July 7, 2022 (87 FR 40460). The NPRM was prompted by
reports of latent failures of the cabin altitude pressure switches, and
the determination that using certain adapters while performing a
functional test may lead to false failures of the cabin altitude
pressure switches. In the NPRM, the FAA proposed to retain the
repetitive functional tests and on-condition actions, and specify
certain adapter requirements for the functional tests. The FAA is
issuing this AD to address the unexpectedly high rate of latent failure
of both pressure switches on the same airplane, which 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.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from the Air Line Pilots Association
(ALPA), who supported the NPRM without change.
The FAA received additional comments from four commenters,
including United Airlines, Delta Air Lines, American Airlines, and
Boeing. The following presents the comments received on the NPRM and
the FAA's response to each comment.

Request To Revise Note 1 to Paragraph (g)

Delta Air Lines (DAL) asked that the FAA revise note 1 to paragraph
(g) of the proposed AD to call out equivalent applicable Boeing 737
Aircraft Maintenance Manual (AMM) procedures, in addition to calling
out the procedures in the 737 Task Card. DAL stated that the 737 Task
Cards called out in Note 1 to paragraph (g) of the proposed AD are not
easily accessible to the maintenance personnel performing the tasks on
the aircraft. DAL added that the AMM procedure is more commonly used
and easily accessed by the Aircraft Maintenance Technician, so the
addition of the reference to the AMM procedure avoids potential
confusion when the maintenance task is being performed.
The FAA agrees with the commenter's request for the reasons
provided. The FAA has revised Note 1 to paragraph (g) of this AD to
include the equivalent applicable Boeing 737 Aircraft Maintenance Manual
procedures referenced in Delta's comment.

Request To Correct Typographical Error

DAL noted that Boeing 737-600/700/800/900 Aircraft Maintenance
Manual (AMM) is identified in note 1 to paragraph (g) of the proposed
AD as ``Airplane Maintenance Manual'' instead of ``Aircraft Maintenance
Manual.''
The FAA has corrected the reference accordingly.

Request To Return to MRB Interval

United Airlines (UAL) asked that the interval established in the
Maintenance Review Board (MRB) be eventually re-established. UAL stated
that tooling was determined to be a significant contributor to
inconsistencies in the testing of the cabin altitude test switch. UAL
added that AD 2021-14-20 would be superseded by the proposed AD to
require improved AMM content defining appropriate tooling. In light of
these published AMM improvements, UAL recommended a return to the
interval established in the MRB.
The FAA does not agree with the commenter's request. Boeing
provided the fleet data collected from AD 2021-14-20 and the trend data
after operators incorporated the improved AMM content. The FAA
evaluated this data and determined through risk analysis that the
interval established in the MRB was unacceptable. Therefore, the FAA
has not changed this AD in this regard.

Request To Remove Hose Length Requirement

American Airlines (AA) stated that the FAA should remove the hose
length requirement of ``25 to 40 ft'' specified in figure 1 to
paragraph (g) of the proposed AD. AA stated that the hose length
requirement is an unnecessary restriction. AA added that a longer or
shorter hose should not significantly affect the application of a
controlled vacuum, and therefore should not affect the accuracy of the
cabin altitude pressure switch functional test.
The FAA does not agree with the commenter's request. There are
instructions to use a Barfield Pitot Hose, or equivalent 25- to 40-foot
hose, to standardize the equipment that operators use while performing
the cabin altitude warning switch functional test and to prevent false
test failures. There is potential concern that a hose longer than 40
feet could have a kink in the hose that may be unnoticed by the
operator, which could result in a false test failure. The FAA has not
changed this AD in this regard.

Request To Use Specific Adapters for Functional Test

Boeing asked that the proposed AD not specify particular adapters
for use during performance of the pressure switch functional test.
Boeing stated that the proposed AD should instead direct operators to
use only those adapters listed in the current Boeing AMM revision or
subsequent revisions. Boeing added that if new or improved adapters
become available and/or the AMM adapter list is modified, an
alternative method of compliance (AMOC) will have to be approved to add
them as approved adapters for the AD, which is not an efficient
resolution.
The FAA does not agree to require operators to use only those
adapters listed in the existing Boeing AMM revision or subsequent
revisions. Figure 1 to paragraph (g) of this AD shows the same list of
adapters identified in the current Boeing AMM. Approval of an AMOC to
use new or improved adapters would not be necessary if the adapters
meet the specifications in either paragraph (g)(2)(i) or (ii) of this
AD. Therefore, the FAA has not changed this AD in this regard.

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, and
any other changes described previously, this AD is adopted as proposed
in the NPRM. None of the changes will increase the economic burden on
any operator.

Costs of Compliance

The FAA estimates that this AD affects 2,693 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated costs

Action Labor cost Parts cost Cost per product Cost on U.S. operators
Functional test 1 work-hour x $85 per hour = $85 per test *$ $85 per test $228,905 per test

* If the operator needs to buy an adapter, the FAA estimates the adapter
could cost up to $3,644. The FAA has no way of determining the number of
operators that might need to purchase an adapter.

The FAA estimates the following costs to do any necessary on-
condition actions required based on the results of the functional test.
The FAA has no way of determining the number of aircraft that might
need these actions:

On-Condition Costs

Action
Labor cost
Parts cost
Cost per product
Switch replacement 1 work-hour x $85 per hour = $85
$1,278
$1,363

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.
The 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
is likely to exist or develop on products identified in this rulemaking
action.

Regulatory Findings

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

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness (AD) 2021-14-20, Amendment 39-21647 (86 FR
38214, July 20, 2021); and

b. Adding the following new AD: