The Federal Aviation Administration has adopted a new airworthiness directive, effective November 20, 2025, targeting certain MHI RJ Aviation ULC regional jet models. This directive responds to reports of loose and missing bolts on the horizontal stabilizer anti-yaw steady fitting block, a critical component for maintaining aircraft stability. Issued as AD 2025-22-02, it mandates repetitive torque checks to mitigate risks that could result in loss of the horizontal stabilizer during events like bird strikes or gust loading, potentially leading to loss of control. The action affects models including the CL-600-2C10, CL-600-2C11, CL-600-2D15, CL-600-2D24, and CL-600-2E25, previously under Bombardier's type certificate. Prompted by a Transport Canada mandate, this measure underscores ongoing international collaboration in aviation safety, with immediate adoption justified by the severity of the unsafe condition.
Background and Unsafe Condition
Reports emerged during routine maintenance on the horizontal stabilizer, where a bolt from the anti-yaw steady fitting block was found missing, with associated hardware discovered on nearby structures. Additional bolts in the same group were loose. The anti-yaw steady fitting block lacks a secondary locking feature, making it vulnerable to vibration-induced loosening over time. Transport Canada, the state of design authority for these aircraft, identified this issue in its AD CF-2025-38, dated August 19, 2025. The FAA's adoption aligns with bilateral agreements, determining that the condition could exist on U.S.-registered aircraft. If unaddressed, loose or missing bolts combined with external forces like bird strikes or turbulence might cause the horizontal stabilizer to detach, resulting in catastrophic loss of control. This directive applies to 597 U.S.-registered airplanes, highlighting the widespread use of these regional jets in commercial aviation.
Key Players and Regulatory Process
The FAA, under the Department of Transportation, leads this initiative, with Fatin Saumik as the primary aviation safety engineer contact. MHI RJ Aviation ULC, successor to Bombardier Inc., holds the type certificate for the affected models. Transport Canada's involvement is pivotal, as its AD CF-2025-38 serves as the mandatory continuing airworthiness information incorporated by reference. The FAA's process bypasses standard notice-and-comment due to the urgent safety risk, invoking 'good cause' under the Administrative Procedure Act. This immediate adoption reflects precedents in aviation regulation, such as prior ADs for similar structural integrity issues in regional jets, including those addressing fatigue cracking in stabilizers (e.g., FAA ADs related to Bombardier models). Political forces include international harmonization efforts, driven by agreements like the U.S.-Canada Bilateral Aviation Safety Agreement, which facilitate mutual recognition of safety standards.
Requirements and Compliance Details
Operators must perform repetitive torque checks on the four attachment bolts of the horizontal stabilizer anti-yaw steady fitting block. These checks involve inspecting tightening torque, replacing any loose or missing bolts and nuts, and re-torquing all hardware. Initial compliance is required within specified flight hours from the AD's effective date, with repeats every 2,200 flight hours. The directive incorporates Transport Canada AD CF-2025-38 procedures but includes exceptions, such as using 'flight hours' instead of 'hours air time' and adjusting compliance timelines to the FAA AD's effective date. An optional terminating action allows replacement of the fitting block hardware, including measuring hole diameters, reaming if necessary, and installing new bolts, nuts, washers, and cotter pins to add a double safety device. This replacement, detailed in the Canadian AD, is not mandatory in the FAA version but could become so in future rulemaking, with the FAA seeking comments on its merits by December 22, 2025.
Implications and Perspectives
Short-term implications include immediate operational burdens for airlines, with estimated costs of up to $510 per aircraft for torque checks and $622 for optional replacements, totaling up to $304,470 for the U.S. fleet. On-condition repairs for loose bolts add minimal costs, around $113 per instance. These measures ensure continued airworthiness but may disrupt maintenance schedules. Long-term, the directive could influence design standards for future aircraft, emphasizing secondary locking features in critical fittings. From an industry perspective, manufacturers like MHI RJ may advocate for the terminating replacement to reduce ongoing inspection costs, while operators might prefer phased implementation to minimize downtime. Regulators view this as a proactive step in risk mitigation, aligning with broader FAA goals under 49 U.S.C. 44701 for promoting safe air commerce. Critics, however, could argue the immediate adoption limits stakeholder input, though the FAA justifies it by the potential for imminent harm. No endorsements are made here, but these viewpoints reflect debates in aviation safety policy.
In summary, this airworthiness directive addresses a critical vulnerability in MHI RJ regional jets, mandating inspections to prevent stabilizer failure. Potential next steps include public comments on incorporating the hardware replacement as mandatory, which could terminate repetitive checks. Ongoing challenges involve balancing safety with operational efficiency, while debates may center on harmonizing U.S. and Canadian regulations further. Future trajectories could see similar ADs for other models if comparable issues arise, reinforcing the need for vigilant maintenance in aging fleets.