Bombardier issued several Service Bulletins (SBs) focusing on the inspection and modification of ailerons across the Learjet 40, 45, 70, and 75 fleets. These SBs were issues August 4, 2025, with recommended compliance within six months.
With approximately 600 to 700 aircraft affected, this bulletin aims to mitigate potential structural issues by improving balance weights to prevent corrosion and cracking.
While currently classified as a recommended Service Bulletin, there is significant industry speculation that this could transition into a mandatory Airworthiness Directive (AD). At Duncan Aviation, we advise operators to take a proactive approach to ensure fleet safety and maintain aircraft valuation.
Service Bulletin Scope and Requirements
The primary goal of SB 45-27-54 is to identify and resolve underlying structural concerns within the aileron assembly. The SB requires NDT inspection of the aileron forward spar and balance weight support structure for cracking, along with the installation of larger diameter washers for the balance weight attaching hardware. This modification is designed to improve weight distribution and mitigate the stresses that lead to cracking.
Expert Compliance Required
This is not a standard remove-and-replace task. It requires significant structural expertise and specialized tooling. We highly recommend you select a facility with specific Learjet structural experience.
Duncan Aviation technicians are fully trained and have already completed numerous compliance events for this specific SB. When we open the aircraft, we document all findings meticulously and provide a comprehensive report to Bombardier.
Scheduling and Downtime
The most efficient way to handle this SB is to pair it with a scheduled maintenance event. However, we are able to accept standalone compliance.
Downtime for standalone or send-in is approximately 2 to 3 weeks for compliance. Please note that discrepancies found during inspection or parts lead times can extend this window.
The Duncan Aviation Advantage
Whether you choose to bring the entire aircraft to one of our full-service facilities or send the ailerons to our team, you will receive the component back with a completed Form 8130, ensuring your aircraft remains compliant and ready for flight.
To schedule your aircraft for this Service Bulletin, reach out to a Duncan Aviation Bombardier Airframe Service Sales Rep.
February 2026
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