Cirrus Releases Update on Vision Jet Grounding

The FAA last Friday grounded all Cirrus Vision Jets through an Emergency AD prompted by Cirrus reporting three incidents on Cirrus Model SF50 airplanes of the stall warning and protection system (SWPS) or Electronic Stability & Protection (ESP) System engaging when not appropriate. Over the weekend, Cirrus senior vice president of sales and marketing Ben Kowalski told Flying, "Out of an abundance of caution, we immediately began working with the FAA and our internal teams to determine the root cause and began our operator communication process. We proactively and quickly issued two service advisories and one mandatory service bulletin to ensure our operators were up to speed on the issue and to remind them of the proper airplane flight manual (AFM) procedures to follow in case of an angle of attack (AOA) related issue. We then quickly identified the root cause as an AOA sensor hardware issue, not a software issue."

Cirrus issued a service bulletin on April 8 and another on April 12, “requiring operators to replace their AOA hardware sensor and, along with a prescribed AOA hardware preflight inspection, allowed five hours of flight time to reposition the aircraft for this maintenance.” Last Friday’s AD also required replacing the AoA indicators but did not allow the five-hour flight timeframe for completion.

The language reported in the Emergency AD explained, “Cirrus and Aerosonic (manufacturer of the technical standard order AOA sensor) have identified the probable root cause as an AOA sensor malfunction due to a quality escape in the assembly of the AOA sensor at Aerosonic. Two set screws that secure the potentiometer shaft to the AOA vane shaft may have improper torquing and no application of thread locker.”

Kowalski added, “A quality escape, in this case, means the AOA hardware unit was not manufactured correctly by the supplier. Cirrus Aircraft installed the unit correctly in the aircraft, but the unit we installed wasn’t built to its design specification.” He said, “Our AOA hardware supplier is now producing corrected AOA hardware sensors which are beginning to ship to operators now. These new, corrected AOA hardware sensors will be installed on fielded aircraft and new aircraft deliveries.”

No word at present on how long it will take Aerosonic to supply enough new AOAs to put the entire fleet of about 100 Vision Jets back in the air.