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 De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. The NPRM was published in the Federal Register on January 7, 2026 (91 FR 454). The NPRM was prompted by AD CF-2025-19, dated March 24, 2025 (Transport Canada AD CF-2025-19) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states there have been reports of multiple instances of in-service cracking in the elevator PCU brackets (fittings) located on the horizontal stabilizer rear spar, as well as four cases of cracking on the elevator front spar. In one case, the cracking progressed to the point where the PCU bracket detached. An investigation determined that the common contributing factor in all cases was force-fight loads generated during elevator movement by the PCUs. Potential root causes identified include elevator system mis-rigging, improper clamping of PCU brackets due to insufficient shimming, and misalignment of the horizontal stabilizer and elevator hinges during assembly.

In the NPRM, the FAA proposed to require replacing bushings and installing new washers on the elevator PCU arm fitting assembly, installing doublers at the front spar of the elevator structure assembly, replacing horizontal stabilizer rear spar elevator PCU fittings, and applicable on-conditions actions, as specified in Transport Canada AD CF-2025-19. The FAA is issuing this AD to address cracks in the elevator PCU brackets (fittings) and the elevator front spar, which could result in failure of an elevator PCU bracket and lead to an elevator jam. The unsafe condition, if not addressed, could, if both elevators are affected, result in the loss of pitch control.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-5402.

Discussion of Final Airworthiness Directive

Comments

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

Conclusion

These products have been approved by the civil 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, that authority has notified the FAA of the unsafe condition described in the MCAI referenced above. 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, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

Terminating Action Explanation for Related Transport Canada AD

The accomplishment of certain actions required by this AD, as specified in Transport Canada AD CF-2025-19, terminates inspections required by Transport Canada AD CF-2024-10, dated March 1, 2024, which corresponds to FAA AD 2025-19-05, Amendment 39-23145 (90 FR 46340, September 26, 2025) (AD 2025-19-05). Paragraph (j) of AD 2025-19-05 provides the terminating action that corresponds to the terminating action specified in paragraph C of Part I and paragraph D of Part II of Transport Canada AD CF-2025-19.

Material Incorporated by Reference Under 1 CFR Part 51

Transport Canada AD CF-2025-19 specifies the following procedures:

• Replacing bushings and installing new washers on the elevator PCU arm fitting assembly, which includes inspecting bushing holes in the arm fitting assembly for corrosion, scoring, and structural degradation (i.e., hole diameters are not within specified diameters).
• Installing doublers between ribs 12 and 13 and between ribs 13 and 14 at the front spar of the elevator structure assembly and applicable on-condition actions. The installation includes a detailed visual inspection of the ( printed page 23010) elevator front spar caps and detailed inspection of the upper skin panel for damage ( i.e., cracking or corrosion), a bolt hole eddy current inspection for cracking at certain fastener holes, a high frequency eddy current for radial cracking at bend radius of certain rib lightening holes, and an inspection of the pressure sensitive lightening tape on certain lightening holes for missing or torn tape. On-condition actions include contacting the DHC technical helpdesk for an approved repair, contacting DHC technical helpdesk for support, and replacing pressure sensitive lightening tape with new tape.
• Replacing horizontal stabilizer rear spar elevator PCU fittings, which includes an eddy current inspection, if fittings are removed, for cracking at all mating holes on the spar web assembly and the lower skin.

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

The FAA has received no definitive data on which to base the cost estimates for the on-condition actions specified in this AD.

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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.

The Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

2026-08-07 De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.): Amendment 39-23315; Docket No. FAA-2025-5402; Project Identifier MCAI-2025-00425-T.

(a) Effective Date

This airworthiness directive (AD) is effective June 3, 2026.

(b) Affected ADs

None.

(c) Applicability

This AD applies to De Havilland Aircraft of Canada Limited (type certificate previously held by Bombardier, Inc.) Model DHC-8-401 and -402 airplanes, certificated in any category, as identified in Transport Canada AD CF-2025-19, dated March 24, 2025 (Transport Canada AD CF-2025-19).

(d) Subject

Air Transport Association (ATA) of America Code 55, Stabilizers.

(e) Unsafe Condition

This AD was prompted by multiple in-service reports of cracks found in the elevator power control unit (PCU) brackets (fittings) and the elevator front spar. The FAA is issuing this AD to address such cracks, which could result in failure of an elevator PCU bracket and lead to an elevator jam. The unsafe condition, if not addressed, could, if both elevators are affected, result in the loss of pitch control.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Requirements

Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, Transport Canada AD CF-2025-19.

(h) Exceptions to Transport Canada AD CF-2025-19

(1) Where Transport Canada AD CF-2025-19 refers to its effective date, this AD requires using the effective date of this AD.

(2) Where Transport Canada AD CF-2025-19 refers to hours air time, this AD requires using flight hours.

(3) If, during any inspection required by paragraph (g) of this AD, any corrosion, scoring, or structural degradation of the bushing holes in the arm fitting assembly is found, before further flight, repair using a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or De Havilland Aircraft of Canada Limited's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature.

(4) Where the material referenced in Transport Canada AD CF-2025-19 specifies contacting the DHC technical helpdesk for an approved repair or support, for this AD, a repair must be done before further flight using a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or De Havilland Aircraft of ( printed page 23011) Canada Limited's Transport Canada DAO. If approved by the DAO, the approval must include the DAO-authorized signature.

(5) Where the material referenced in Transport Canada AD CF-2025-19 specifies replacing pressure sensitive lightening tape if required, for this AD, replace the pressure sensitive lightening tape before further flight if tape is missing or torn.

(6) If, during any inspection required by paragraph (g) of this AD, any cracking at any mating hole on the spar web assembly or the lower skin is found, before further flight, repair using a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or De Havilland Aircraft of Canada Limited's Transport Canada DAO. If approved by the DAO, the approval must include the DAO-authorized signature.

(i) Additional AD Provisions

The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, International Validation 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 International Validation Branch, send it to the attention of the person identified in paragraph (j) of this AD and email to: AMOC@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office.

(2) Contacting the Manufacturer: For any requirement in this AD to obtain instructions from a manufacturer, the instructions must be accomplished using a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or De Havilland Aircraft of Canada Limited's Transport Canada DAO. If approved by the DAO, the approval must include the DAO-authorized signature.

(j) Additional Information

For more information about this AD, contact Yaser Osman, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: 9-avs-nyaco-cos@faa.gov.

(k) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this material as applicable to do the actions required by this AD, unless this AD specifies otherwise.

(i) Transport Canada AD CF-2025-19, dated March 24, 2025.

(ii) [Reserved]

(3) For Transport Canada material identified in this AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca. You may find this material on the Transport Canada website at tc.canada.ca/en/aviation.

(4) 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.

(5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/​federal-register/​cfr/​ibr-locations or email fr.inspection@nara.gov.

91 FR 23009