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AGENCY:
Federal Aviation Administration (FAA), DOT.
ACTION:
Final rule.
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; websitemyboeingfleet.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 atregulations.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
| Action | Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
|---|---|---|---|---|
| Revise AFM (retained action from AD 2019-25-17) | 1 work-hour × $85 per hour = $85 | $0 | $85 | $147,815. |
| Install software and perform configuration check (new actions) | 2 work-hours × $85 per hour = $170 | Up to $975 | Up to $1,145 | Up to $1,991,155. |