The FAA notified pilots and aircraft owners about an issue with Garmin’s GFC 500 autopilot equipped with optional auto trim. These autopilots are installed in certified, experimental, and light sport aircraft. Garmin issued its own Service Alert (22109 REV A).
According to the FAA, "This issue may result in an uncommanded automatic trim runaway when the autopilot is first engaged. This condition could result in a sudden and significant deviation from the intended flight path.” However, this does not affect Cirrus aircraft equipped with the GFC 500 autopilot, Garmin said.
For experimental aircraft with the GFC 500, Garmin Service Bulletin 22112 explains how to update the autopilot’s software, which resolves the problem. “Impacted owners and operators of certified aircraft need to temporarily disable the autopilot or visit their Garmin dealer to have the GFC 500 pitch trim control disabled. Disabling trim control will allow for continued use of the autopilot as a temporary option until new GFC 500 software is certified,” Garmin said. The new software is expected to be certified by year-end. Meanwhile, customers can disable the electric pitch trim by referring to Service Bulletin 22110 REV A.
“Customer safety and product quality and reliability are Garmin’s top priority,” the company said. “We will continue to issue updates as more information becomes available.”