Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This proposed AD would require repetitive cleaning/inspecting of the drain hole of each pitot static probe and repetitive cleaning of the pitot lines in the pitot static system. This proposed AD results from reports of incidents of airspeed mismatch between the pilot, co-pilot, and standby airspeed indications caused by contamination in the pitot static system. We are proposing this AD to prevent erroneous/misleading altitude and airspeed information from a contaminated pitot static system to the flightcrew, which could reduce the ability of the flightcrew to maintain the safe flight and landing of the airplane.