CEN21LA232

The pilot reported that, during an instrument flight rules flight, he began receiving conflicting information from the flight instruments and digital flight information display. He stated that the turn coordinator and GPS were displaying opposite information, the heading bug was moving erratically, and he felt as if he was flying in circles. After determining that he could not rely on the information from the flight instruments, he elected to activate the Cirrus airframe parachute system. The airplane came to rest in a stand of trees, resulting in substantial damage. Postaccident testing of the electronic horizonal situation indicator, directional gyro, and horizon reference indicator revealed no anomalies except for the directional gyro counterclockwise heading stability, which exceed the testing limits by about 3°. The heading stability finding, although outside the testing limits, would not result in the instrument anomalies reported by the pilot. The reason for the flight instrument disagreement/malfunction could not be determined based on the available information.

On May 15, 2021, about 2115 central daylight time, a Cirrus SR22, N4144B, sustained substantial damage when it was involved in an accident near Whitewater, Wisconsin. The pilot and passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to the pilot, while on an instrument flight rules flight, he began receiving conflicting information from the flight instruments and digital flight information display. He stated that the turn coordinator and GPS were displaying opposite information, the heading bug was moving erratically, and he felt as if he was flying in circles. After determining that he could not rely on the information from the flight instruments, he elected to activate the Cirrus airframe parachute system. The airplane came to rest in a stand of 60-ft-tall trees, resulting in substantial damage. The airplane was equipped with a Sandel SN3308 electronic horizontal situation indicator (EHSI), Mid-Continent 4305-150 directional gyro, BF Goodrich Aerospace horizon reference indicator, and the pilot was utilizing Foreflight on a personal tablet. A postaccident examination of the airplane revealed no pre-impact mechanical anomalies that would have precluded normal operation. External power was supplied to the airplane and all instruments powered up normally. The airplane was situated on a movable dolly cart which allowed for it to be manipulated to verify instrument functionality. The turn coordinator operated as designed when the empennage was moved, as did the horizon reference indicator. The EHSI powered up but displayed a configuration error; however, the remote gyro wire harness wires were cut during recovery and the flux detector was disconnected. The EHSI, directional gyro, and horizon reference indicator were removed and subsequently tested. The EHSI was connected to an automated tester, which tested the inputs and outputs of the unit. The unit passed all tests. The directional gyro was connected to 28V DC power. The heading was steady and did not drift. The unit passed all testing with the exception of counterclockwise heading stability. The limit for the test was ±2°, but the unit was at +5°. When the unit was shut down, the rotor coasted in excess of 9 minutes, consistent with a free and stable rotor. The horizon reference indicator was connected to an external power source and allowed time to steady the gyro. After caging the gyro, the unit was pitched up and down as well as rolled left and right. The unit responded as designed through all movements. Power was removed and the gyro coasted to a stop, consistent with a free gyro.