Date: 202003
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Cruise
Airspace: Class G ZZZ
ATC / advisory: CTAF ZZZ
Aircraft component: Attitude Indicator(Gyro/Horizon/ADI)
Component problem: Failed; Malfunctioning
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Private
Human factors: Troubleshooting; Workload; Situational Awareness; Distraction; Confusion
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: This report is in reference to an avionic anomaly. I recently had a Bendix King KI300 attitude indicator installed in my aircraft along with a Bendix King KI310 autopilot adapter to direct the Bendix King KFC200 autopilot. The back story is my original Bendix King KI256 attitude indicator failed on arrival at ZZZ1 last year. Company Y recommended the KI300 as a replacement AI; and same could be used as a backup AI in the future should I make other avionics upgrades; such as a Garmin G500txi Primary Flight Display. Company Y completed the work and I flew the plane home; a total of 5.6 hours with no known issues.  I embarked on a training flight and found while in ground operations; the AI would indicate a nose low left turn.  Being the flight conditions were Visual Meteorological; I departed the airport.  The AI was slow to respond; but did eventually indicated a wings level attitude.  When entering a standard rate turn; the indicator would show a nose low (up to 20 degrees low) turn to the left. When entering wings level the indicator would show a nose high pitch attitude of +20 degrees.I contacted Company Y; Mr. Y said it must be a bad unit. I contacted Company Z; the manufacturer of the unit for assistance. The unit was removed and sent back for recalibration. Upon return and reinstallation; the unit again failed inflight as previously described. The unit was again removed and sent back to Company Z.  Company Z sent a new unit for installation.  Upon installing said new unit; that unit failed after 1.5 hours of flight while in a standard rate turn in a holding pattern.Bendix King is of no help nor has the installer Company Y been of assistance.  Company Z is befuddled and I have not heard anything further from Company Y; or Bendix King as of this writing.  The plane has been taken to another avionics installer for removal of the Bendix King KI300 and KI310 for installation of a Garmin G500txi and G5 backup attitude indicator.My concern is that this unit (KI300) may fail in IMC and cause a pilot to experience spatial disorientation and subsequent incident or accident.  I would also be concern to have this unit as a backup attitude indicator for any other type of Primary Flight Display.  I don't know if you have received any other reports; but my experience of having two separate units fail is of concern to me.

Callback: Reporter stated the cause of the failure was still undetermined. Reporter also reiterated the safety risk and concerns with a failure occurring in IMC conditions.



Synopsis: GA pilot reported a recently installed Bendix King KI300 attitude indicator failed after 5.6 hours of total flight time. Reportedly; the failed unit was replaced with a new KI300 unit which subsequently failed as well after only 1.5 hours of flight time.