Airworthiness Directives; Diamond Aircraft Industries Inc. (Type Certificate Previously Held by Diamond Aircraft Industries GmbH) Airplanes

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2009-10-04, Amendment 39-15899 (74 FR 22435, May 13, 2009) (AD 2009-10-04). AD 2009-10-04 applied to certain Diamond Aircraft Industries GmbH (type certificate now held by Diamond Aircraft Industries Inc.) Model DA 40 and DA 40 F airplanes. AD 2009-10-04 was prompted by MCAI originated by the European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union. EASA issued AD 2009-0016, dated January 22, 2009 (EASA AD 2009-0016), to address fatigue cracking of the NLG leg part number (P/N) D41-3223-10-00 at the pivot axle.

AD 2009-10-04 superseded and maintained the requirements of AD 2007-17-06, Amendment 39-15164 (72 FR 46549, August 21, 2007), which required repetitively inspecting the NLG leg for cracks and replacing the NLG leg if cracks were found. The FAA issued AD 2009-10-04 to exclude from the applicability any airplanes that had the improved NLG leg installed.

Effective November 15, 2017, the design and oversight responsibilities for the Model DA 40, DA 40 F, and DA 40 D airplanes were transferred from Diamond Aircraft Industries GmbH of Austria as the design approval holder, and EASA as the civil aviation authority, to Diamond Aircraft Industries Inc. (Diamond), of Canada as the new design approval holder, and Transport Canada as the civil aviation authority. After that transition, Transport Canada received several in-service reports of P/N D41-3223-10-00_1 cracking at the pivot axle and in some cases, fracture of the NLG leg. Investigation revealed that the failures were the result of fatigue cracking.

Since the FAA issued AD 2009-10-04, Transport Canada superseded EASA AD 2009-0016 and issued Transport Canada AD CF-2023-50, dated July 10, 2023 (Transport Canada AD CF-2023-50), to address failure of the NLG leg at the pivot axle by requiring initial and repetitive detailed inspections of NLG leg P/N D41-3223-10-00 and P/N D41-3223-10-00_1 to detect cracking, replacing a NLG leg, as required, with a serviceable part, and prohibiting the installation of NLG leg P/N D41-3223-10-00 or P/N D41-3223-10-00_1 as a replacement part.

Transport Canada AD CF-2023-50 differed from the Diamond material because Transport Canada AD CF-2023-50 required a detailed inspection of the pivot axle of the NLG leg P/N D41-3223-10-00 and P/N D41-3223-10-00_1 using a bright light and 10X magnifying glass instead of Type II visible dye for the inspection of the pivot axle. After Transport Canada AD CF-2023-50 was issued, the repetitive inspection interval was increased from 100 hours air time to 110 hours air time to align with the scheduled 100-hour inspection in chapter 5 of the DA 40 series Airplane Maintenance Manual. To require the change to Transport Canada AD CF-2023-50, Transport Canada issued AD CF-2023-50R1, dated November 29, 2023 (also referred to as the MCAI). The MCAI was published to address the time interval change of the repetitive inspection from 100-hour intervals to 110-hour intervals.

The NPRM published in the Federal Register on July 5, 2024 (89 FR 55525). The NPRM was prompted by failure of a NLG in the area of the pivot axle and changes made to the part replacement options and the repetitive inspections as detailed in the MCAI. The MCAI was published to address the time interval change of the repetitive inspection from 100-hour intervals to 110-hour intervals to align with the scheduled 100-hour inspection in chapter 5 of the DA 40 series Airplane Maintenance Manual.

In the NPRM, the FAA proposed to require repetitive detailed inspections of the NLG leg pivot axle for cracking and if cracking was found replacing that part with a serviceable part. In the NPRM, the FAA also proposed to require eventually replacing all NLG legs having certain part numbers with serviceable parts, if not already done, and prohibit installing affected parts. Replacing affected parts with serviceable parts is terminating action for the repetitive inspections required by this AD.

The FAA is issuing this AD to address the unsafe condition on these products.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2024-1696.

Discussion of Final Airworthiness Directive

Comments

The FAA received no comments on the NPRM or on the determination of the costs.

Conclusion

These products have been approved by the aviation authority of another country and are 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 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. This AD is adopted as proposed in the NPRM.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Diamond Mandatory Service Bulletin MSB 40-091, Rev. 0, dated January 18, 2021, published with Diamond Aircraft Industries Work Instruction WI-MSB 40-091, Rev. 0, dated January 18, 2021 (issued as one document). This material specifies procedures for doing repetitive dye penetrant inspections of the NLG leg pivot axle for cracking and replacing the NLG for Model DA 40 airplanes.

The FAA also reviewed Diamond Mandatory Service Bulletin MSB F4-038, Rev. 0, dated January 18, 2021, published with Diamond Aircraft Industries Work Instruction WI-MSB F4-038, Rev. 0, dated January 18, 2021 (issued as one document). This material specifies procedures for doing repetitive dye penetrant detailed inspections of the NLG leg pivot axle for cracking and replacing the NLG for Model DA 40 F airplanes.

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 ADDRESSES .

Differences Between This AD, the MCAI, and the Material

The MCAI applies to Model DA 40 D airplanes, however, this AD does not because that model does not have an FAA type certificate.

Although the Diamond material specifies to do dye penetrant inspections, the MCAI requires, and this AD requires, using a bright light (minimum of 100 foot-candles) and 10X magnifying glass instead of dye penetrant.

Costs of Compliance

The FAA estimates that this AD affects 693 airplanes of U.S. registry.

The FAA estimates the following costs to comply with this AD: