Accident Overview
On March 28, 2021, at 1428 Pacific daylight time, a Cirrus SR22 GTS, registration N644SR, was substantially damaged during an accident near Marana, Arizona. The pilot and passenger were uninjured. The flight, a personal trip under 14 CFR Part 91, originated from Tucson, Arizona.
Engine Failure Sequence
The pilot reported that takeoff and climb were normal until reaching 10,000 feet mean sea level. At that altitude, the engine shuddered, lost all power, and began shaking the airplane violently. The pilot shut down engine controls, but the propeller continued to windmill, causing the engine to persist in shuddering.
Air traffic control provided a heading to Marana Regional Airport. When the pilot realized the airport was unreachable, the controller issued a heading to a nearby glider port. The pilot expressed confidence in reaching it, but instead chose to deploy the Cirrus Airframe Parachute System (CAPS) at 2,000 feet above ground level. The pilot reported pulling the parachute deployment handle three times, but the parachute did not deploy. He subsequently landed the airplane on a dirt road. During landing, the left wing contacted tall brush, spinning the airplane 180°, resulting in substantial damage to the underside of the wings and fuselage.
Postaccident Wreckage Examination
Postaccident examination revealed the empennage, upper fuselage, engine, and propeller were intact with minimal damage. The landing gear was bent and collapsed; the left flap was deformed. The ballistic parachute compartment was intact and unopened.
About 5 quarts of dark oil were drained from the oil sump. The sump contained broken aluminum and steel engine components. The Nos. 1 and 3 cylinder through bolt and deck stud nuts had torque seal; the remaining cylinders did not. When retorqued, none of the 8 through-bolt nuts tightened before reaching the specified torque. The Nos. 2 and 4 cylinders could not be removed due to internal mechanical damage to their skirts.
The No. 2 connecting rod and piston were separated from the crankshaft. The left half of the No. 2 main bearing had rotated about 15° within the saddle area, overlapping the right half. The left bearing half shifted forward about 1/8 inch from its original position. The corresponding main bearing seal was not positioned properly in the saddle bearing support, resulting in a lack of oil lubrication and discoloration of the connecting rod journal.
The last annual inspection was performed on April 20, 2020, at a Hobbs time of 2130.0 hours. The No. 1 cylinder and piston assembly had been removed, repaired, and reinstalled during that inspection due to low compression.
CAPS Examination
Examination of the Cirrus Airplane Parachute System showed the chute was packed properly, but the rocket motor initiating device (squib) was inoperative. The squib circuit was “open” rather than “closed” as expected for an unfired system. No other anomalies initially identified would have contributed to the system not firing.
CT scans of the squib revealed the bridge wire was broken/activated (fused), but the B1 (boron-barium chromate) primer charge did not ignite properly, preventing ignition of the BKNO3 pellets. The specific reason for the B1 failure was not determined, but several possible factors were identified: a different boron-to-barium chromate ratio in squibs manufactured in 2015, larger boron pieces possibly reducing mixture homogeneity, and high moisture levels noted in the accident squib (though this may have occurred after opening).
Service Bulletins and Advisories
On June 9, 2021, Cirrus issued SB2X-95-27, calling for removal of 25 squib assemblies from the same lot as the accident squib. Testing revealed additional “no-ignition” squibs from that lot. On December 10, 2021, SB2X-95-27R2 expanded the recall to 347 squibs installed in SR20 and SR22 airplanes, manufactured with the same B1 batch. The suspect B1 batch also affected 27 SF50 airplanes; SB5X-90-13 addressed removal of the remaining 26 suspect igniters (one SF50 had been removed from service due to a ground fire).
In August 2022, testing on returned squibs revealed another no-fire squib (serial number 0416-3617) outside the previously identified scope. Consequently, SB20X-95-27R3 was issued on October 14, 2022, expanding the recall by an additional 925 igniters.
Cirrus also issued Service Advisory SA21-16, emphasizing that the CAPS electric ignition checkout procedure in AMM 95-00 must be completed in its entirety during annual inspections, and that CAPS repack certification is not required to perform those tasks.