Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) Airplanes

The FAA is revising an existing airworthiness directive (AD) for certain Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. That AD currently requires repetitive inspections of the left and right engine throttle control gearboxes for wear, and corrective action if necessary. This AD limits the applicability of the existing AD, extends the compliance time for the initial inspection, and clarifies the reporting requirement. This AD is prompted by numerous failures of the engine throttle control gearbox, some of which resulted in an in-flight engine shutdown. We are issuing this AD to prevent excessive wear of the gearboxes and subsequent movement or jamming of the engine throttle; movement of the throttle towards the idle position brings it close to the fuel shut-off position, which could result in an in-flight engine shutdown.