Bombardier reports that 35 out of the 85 Dash 8 Q400 turboprops that had been grounded by a Transport Canada airworthiness directive (AD) issued last week are back in service.

The AD called for all Bombardier Dash 8 Q400 operators to conduct immediate landing gear inspections following two incidents involving Scandinavian Airlines (SAS) aircraft.

Inspections are focused on the gear retract actuator jam nut on the landing gear actuator, a part that Danish investigators have identified as being affected by corrosion in an SAS landing-gear collapse at Aalborg last week.

Bombardier says 70% of the 165 Q400 turboprops in the global fleet are currently in service, including 35 of the 85 aircraft that required a detailed inspection as part of the AD. The airframer had provided Q400 operators with detailed inspection procedures developed by the landing gear manufacturer, Goodrich.

"Bombardier, with the support of Goodrich, continues to focus its efforts on assisting its customers to return to normal flight schedules as quickly as possible," says the company. No word yet on when the remaining 50 aircraft will be inspected.

Horizon Air, which Flight’s ACAS database shows has 33 Q400s, says it will operate 90% of its normal schedule between September 18 and September 24 as it completes the inspections. The airline says it "hopes" to resume its regular schedule on September 25.