DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1497; Project Identifier AD-2023-00516-T;
Amendment 39-22816; AD 2024-16-10]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2019-25-
17, which applied to all The Boeing Company Model 737-600, -700, -700C,
-800, -900, and -900ER series airplanes. AD 2019-25-17 required
revising the existing airplane flight manual (AFM) to prohibit
selection of certain runways for airplanes equipped with certain
software. Since the FAA issued AD 2019-25-17, Boeing has developed new
software to address the unsafe condition. This AD was prompted by
reports of display electronic unit (DEU) software errors on airplanes
with a selected instrument approach to a specific runway. This AD
retains the requirements of AD 2019-25-17. This AD also requires
installing the new software and performing a software configuration
check, which terminates the AFM revision. The FAA is issuing this AD to
address the unsafe condition on these products.

DATES: This AD is effective October 28, 2024.

The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of October 28, 2024.

ADDRESSES:

AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2023-1497; 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.

Material Incorporated by Reference:

For Boeing material identified in this AD, contact Boeing
Commercial Airplanes, Attention: Contractual & Data Services (C&DS),
2600 Westminster Blvd., MC 110 SK57, Seal Beach, CA 90740-5600;
telephone 562-797-1717; website myboeingfleet.com.

You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 2200 South 216th St., Des
Moines, WA. For information on the availability of this material at the
FAA, call 206-231-3195. It is also available at regulations.gov under
Docket No. FAA-2023-1497.

FOR FURTHER INFORMATION CONTACT: Douglas Y. Tsuji, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3548; email: Douglas.Tsuji@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2019-25-17, Amendment 39-21016 (84 FR
71304, December 27, 2019) (AD 2019-25-17). AD 2019-25-17 applied to all
the Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER
(Model 737 NG) series airplanes (although the scope of the AD
requirements is limited to operation at specific runways in the U.S.,
Colombia, and Guyana). The NPRM published in the Federal Register on
August 4, 2023 (88 FR 51739). The NPRM was prompted by reports of
Display Units (DUs) blanking due to Display Electronics Unit (DEU)
software errors on Model 737 NG airplanes flying into runway PABR in
Barrow, Alaska. The investigation revealed that the problem occurs when
a certain combination of software is installed and a susceptible runway
with a 270-degree true heading is selected for instrument approach,
although only seven runways worldwide have latitude and longitude
values that cause the blanking behavior. AD 2019-25-17 was issued to
address the potential for blanking displays on flights into the
affected airports. The software errors and consequent display blanking,
if not addressed, could prevent continued safe flight and landing. In
the NPRM, the FAA proposed to retain the requirements of AD 2019-25-17.
The NPRM also proposed to require installing the new software, and
performing a software configuration check, which would terminate the
AFM revision requirement. The FAA is issuing this AD to address the
potential for all six DUs to blank, which can prevent continued safe
flight and landing.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from the Air Line Pilots Association,
International (ALPA), who supported the NPRM without change.

The FAA received additional comments from three commenters,
including Boeing, Southwest Airlines (SWA), and Pegasus Airlines. The
following presents the comments received on the NPRM and the FAA's
response to each comment.

Request To Continue Utilizing Common Display System Block Point 06

Boeing requested that paragraph (m), "Alternative Methods of
Compliance (AMOCs)," of the proposed AD be revised to allow airplanes
with Common Display System (CDS) Block Point (BP) 06 an AMOC to the
actions specified by paragraph (h) of the proposed AD. SWA requested
allowing airplanes to continue to utilize CDS BP06 in lieu of the
software update that would be required by paragraph (h) of the proposed
AD (i.e., CDS BP15a). Boeing and SWA stated that CDS BP06 does not
contain the error that leads to the display blanking for the specific
airports listed in AD 2019-25-17. SWA also cited a software
incompatibility issue with the Rockwell Collins Head Up Display (HUD)
HGS-2350 (currently installed on 15% of their fleet) and stated that
the new CDS BP15a would require disabling the HUD, which provides the
flightcrew a myriad of safety features enhancements.

The FAA agrees with allowing airplanes with CDS BP06 to be excepted
from the requirements of paragraph (h) of this AD, because CDS BP06
does not contain the error that leads to the display blanking for the
specific airports listed in AD 2019-25-17. The FAA has added a
statement in paragraph (i)(2) of this AD accordingly. The FAA does not
agree with revising paragraph (m) of this AD, because this AD has been
revised to except airplanes with CDS BP06 from the requirements of
paragraph (h) of this AD, thus eliminating the need for the AMOC.

Request for Adding a Note to Paragraph (c), "Applicability"

Pegasus Airlines requested adding a note to paragraph (c),
"Applicability," of the proposed AD as follows: "The scope of the AD
requirements is limited to operation at the seven runways identified in
figure 1 to paragraph (g) of this AD." The commenter stated that the
note was in AD 2019-25-17 and should be included in this AD.

The FAA disagrees with the commenter. The requirements of this AD,
notably the software update, must be done by all applicable airplanes
regardless of runway operation. The FAA has not changed this AD in this
regard.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that the installation of winglets
per Supplemental Type Certificate STC ST00830SE does not affect the
accomplishment of the manufacturer's service instructions.

The FAA agrees with the commenter that STC ST00830SE does not
affect the accomplishment of the manufacturer's service instructions.
Therefore, the installation of STC ST00830SE does not affect the
ability to accomplish the actions required by this AD. 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.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Boeing Alert Requirements Bulletin 737-31A1880 RB,
Revision 1, dated September 16, 2020. This material specifies
procedures for installing the CDS DEU OPS block point 2015A and
performing a software configuration check. This 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.

Costs of Compliance

The FAA estimates that this AD affects 1,739 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

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 Directive (AD) 2019-25-17, Amendment 39-21016
(84 FR 71304, December 27, 2019); and

b. Adding the following new AD: