In response to three recent in-flight incidents that resulted in the grounding of the Cirrus SF50 fleet, the FAA has published a new airworthiness directive for the Cirrus SF50 light jet, reinforcing the emergency AD issued in April.
To address the instances of engagement of the single-engine jet’s stall warning and protection system (SWPS) and/or the electronic stability and protection (ESP), even in cases when sufficient airspeed and proper angle of attack (AOA) existed for normal flight, the AD reiterates the agency’s mandated replacement of its AOA sensors with improved AOA sensors.
The airframer and AOA sensor manufacturer Aerosonic identified the probable root cause of the problem as an AOA sensor malfunction due to “a quality escape in the assembly of the AoA sensor [part number 4677-03] at Aerosonic.” Cirrus issued a service bulletin with instructions for replacing the suspect sensor.
As the agency found that the condition presented an immediate danger to pilots and passengers of the jet when it issued the emergency AD, it waived the usual notice and comment period. As the conditions still exist, the FAA adopted the new AD without prior opportunity for public comment, but for those wishing to do so, any such comments must be received by August 1.