Airworthiness Directives; Embraer S.A. Airplanes

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Embraer S.A. Model EMB-545 and EMB-550 airplanes. The NPRM published in the Federal Register on March 7, 2024 (89 FR 16489). The NPRM was prompted by ANAC AD 2023-08-03R01, effective November 2, 2023 (ANAC AD 2023-08-03R01) (also referred to as the MCAI). The MCAI stated that premature cracks have occurred in the outer layer of left-hand and right-hand flight deck side windows with part number (P/N) NP-200402-7 or P/N NP-200402-8, caused by interference due to manufacturing tolerances.

In the NPRM, the FAA proposed to require initial and repetitive inspections of the flight deck side windows and applicable corrective actions, and to prohibit the installation of affected flight deck side windows, as specified in ANAC AD 2023-08-03R01. The FAA is issuing this AD to address cracks, delamination, scratches, erosion, and any other damage with the affected left-hand and right-hand flight deck side windows, which may subject the inner layer of the window to unpredicted loads for several flights, which could result in window failure and subsequent in-flight depressurization events.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2024-0455.

Discussion of Final Airworthiness Directive

Comments

The FAA received one comment, from Embraer S.A. The following presents the comment received on the NPRM and the FAA's response to the comment.

Request for Change to Exceptions Paragraph

Paragraph (b)(1)(i) of ANAC AD 2023-08-03R01 specified replacement of a window if “any crack in the outer layer” is detected. Paragraph (h)(2) of the proposed AD, however, specified replacement of a window if “any crack, delamination, or any other damage” is found. Embraer stated that delamination is commonly defined as a reduced adhesion or separation of the interlayer between the acrylic plies. Embraer claimed that delamination is found with some frequency in airplane windows and may be present during the inspection. Embraer added that delamination, as well as other typical damage (scratches, crazing, etc.) is not a structural concern, but would require the immediate window replacement according to the proposed AD. Embraer was concerned that the text of the proposed AD would require actions beyond the original intent of the ANAC AD, which is to provide instructions if a crack is identified. Embraer claimed that a crack in the window outer ply caused by the interference with its aluminum strap is the condition that may develop into the unsafe condition.

Since the commenter submitted the comment, ANAC has revised the MCAI. ANAC AD 2023-08-03R02, effective May 10, 2024 (ANAC AD 2023-08-03R02), clarifies the corrective actions for damages other than cracks, although it does not change the intent: If any crack in the outer layer is found, the revised MCAI requires replacing the window, and if delamination, scratches, erosion, or any damage other than a crack is found, the revised MCAI requires corrective actions that depend on the extent of the findings, as specified in Task 56-12-00-200-802-A, “Cockpit Side Window—Allowable limits,” Revision 50, dated May 12, 2023, as published in Aircraft Maintenance Manual AMM-5613, Part II (Maintenance Practices and Procedures-MPP), or further revisions of this task approved by ANAC.

The FAA affirms that maintenance procedures exist with limits defined by the window manufacturer in case of delamination, scratches, erosion, or any other damage. With the updated procedures, the FAA therefore agrees that the exception specified in paragraph (h)(2) of the proposed AD is unnecessary. The FAA has made the following changes to this AD:

• Paragraph (g) of this AD requires the actions specified in ANAC AD 2023-08-03R02 (instead of ANAC AD 2023-08-03R01).
• Paragraph (h)(2) of the proposed AD has been removed from this AD.
• Paragraph (i) has been added to this AD to provide credit if the actions in ANAC AD 2023-08-03R01 were accomplished before the effective date of this AD.

Conclusion

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA reviewed the relevant data, considered the 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 this product. 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 ANAC AD 2023-08-03R02, effective May 10, 2024. This material specifies procedures for initial and repetitive general visual inspections of the left-hand and right-hand flight deck side windows with P/N NP-200402-7 or P/N NP-200402-8 to detect cracks, delamination, scratches, erosion, and any other damage (such as chipping and crazing). Corrective actions include window replacement and other maintenance procedures depending on the extent of the findings. ANAC AD 2023-08-03R02 also prohibits the installation of flight deck side windows with P/N NP-200402-7 or P/N NP-200402-8, on any airplane.

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 this AD affects 44 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: