Date: 201702
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Gulfstream G280
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class D ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Autopilot
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We took off normally; it was a cold; clear morning. We were assigned 3;000 feet and heading 060 after takeoff. At 2;000 feet in the turn; the PF turned on the autopilot. Upon reaching 3;000 feet; the autopilot decreased pitch and the autothrottles came back to maintain 200 knots and 3;000 feet. At the same time; we received further climb to 5;000 feet. During the radio exchange; the aircraft continued to decrease pitch without increasing power and started to descend. Around 2;950 feet; the PF disconnected both autopilot and autothrottles to prevent the autopilot from descending further. By the time the PF was able to return the aircraft to a pitch and power setting that would allow the aircraft to climb; we were down to approximately 2;700 feet. Around 3;500 feet; we reengaged the autopilot and autothrottles and both functioned as intended. We continued our climb to 5;000 as instructed with no remark from ATC.On the subsequent flight; we departed runway heading; with a turn to 230. After takeoff; I set the heading to 230 and turned on the autopilot; and the aircraft immediately started rolling to the right. The PF disconnected the autopilot and turned the aircraft in the correct direction. After reengaging the autopilot; it functioned as intended again.On both flights; the autopilot was programmed correctly beyond a shadow of a doubt.


Second narrative: On the following leg; on takeoff we were cleared to 4000 initially with a 40 degree left turn. HDG; FLCH with alt armed was selected. In attempt to recreate the initial event I turned on the autopilot at 2000. The aircraft immediately began an incorrect right turn; when HDG was selected and clearly targeting 40 degrees left. I selected the SYNC (TCS) button to interrupt the turn immediately. When I let go of the SYNC (TCS) button the aircraft continued its right turn. I disconnected the autopilot and autothrottles and turned left as directed. We only ended up about 5 degrees right; but it was a noticeable uncommanded turn contrary to the flight director's commands. Altitude mode was flown and continued correctly. The flight continued as normal after the Autopilot was selected on again.


Synopsis: G280 flight crew reported autopilot anomalies on two flights. Reporters mentioned the autopilot was set correctly in both situations; but the aircraft did not react appropriately.