Accident Sequence
On September 7, 2018, at about 1500 central daylight time, a Cirrus SR-22T airplane, registration N131TX, was substantially damaged when it crashed near Kennett, Missouri. The private pilot and one passenger sustained minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
During the takeoff roll, the pilot noticed that the active noise reduction (ANR) function of his headset was not operating. The ANR activation button is located on a control module on the headset cord. The pilot tugged on the cord to access the button, but the module was wedged between his seat and the center console. He proceeded with the takeoff, intending to free the module once airborne.
When the airplane reached about 200 ft above ground level (agl), the pilot engaged the autopilot set to capture 3,000 ft mean sea level (about 2,700 ft agl). He then leaned down and focused on freeing the control module. Within seconds, without freeing it, he sensed a significant decrease in engine noise and power. He sat upright, verified the engine power and mixture levers were correctly positioned, and began scanning the instrument panel. An aural "sink rate" warning then activated. Unable to determine the cause of the power loss, he asked his wife (who was not a pilot but familiar with the airplane) their altitude; she responded "640" ft.
The airplane was equipped with the Cirrus Airframe Parachute System (CAPS). The pilot realized the altitude was near or possibly below the minimum recommended CAPS deployment altitude but decided deployment was the best option for survival. The extraction rocket fired, the parachute opened, and the airplane impacted the ground during its first tail-first swing after parachute deployment, coming to rest upright in a field. The fuselage was substantially damaged.
The pilot noted it was possible that he inadvertently repositioned the fuel boost pump switch, located on the center console, to the HIGH BOOST/PRIME position while attempting to free his headset control module.
Aircraft Fuel Pump System
The airplane was equipped with an electrically powered fuel boost pump. A three-position rocker switch (Boost, Off, High Boost/Prime) was located on the horizontal surface of the center console between the two forward seats, just left of the engine power lever. The pump is unpowered when the switch is neutral. Pressing the forward end powers the pump in Boost mode (used for takeoff, climb, landing, and tank switching). Pressing the aft end powers High Boost/Prime mode (used for engine priming and suppressing vapor above 18,000 ft with hot fuel). The switch was not guarded against inadvertent operation.
The Pilot’s Operating Handbook states: "To prevent over-priming during low power settings, the system uses a lockout relay that only allows HIGH BOOST/PRIME fuel pump operation when manifold pressure is greater than 24 in. Hg." When manifold pressure exceeds 24 in. Hg, pressing HIGH BOOST/PRIME turns the pump on in low-speed mode.
Wreckage Examination
Examination revealed the CAPS parachute was still attached. The engine and cowling were almost completely fracture-separated from the fuselage. The windshield was fractured into multiple pieces. The headset cord was wrapped around the engine power lever, and the fuel pump switch was found in the HIGH BOOST/PRIME position. No other non-impact damage or abnormalities were observed.
Post-Accident Actions
About four months before the accident, Cirrus began implementing software changes to prevent improper operation of the electric fuel boost pump. The approach involved a software-controlled lockout feature retroactively applied via service bulletins (SBs). The revised software locks out the high boost function of the pump (when HIGH BOOST/PRIME is selected) until the airplane reaches a pressure altitude of 10,000 ft, preventing engine power loss at low altitudes due to improper selection.
The SBs differed based on avionics platforms. Perspective Plus-equipped airplanes were addressed by SB2X-42-14 on May 30, 2018. Perspective-equipped airplanes (the accident model) were addressed by SB2X-42-15 on November 14, 2018, about two months after the accident. That SB was superseded by SB2X-42-17 on March 18, 2019. SB2X-42-16, issued February 1, 2019, addressed 48 new-production model year 2019 airplanes. Although Cirrus categorized all as "mandatory," compliance was not mandated by the FAA. All subsequent new-production Cirrus airplanes are equipped with the lockout software.