Electrical system event involving a Cirrus SR22, VH-LBQ, near Kingaroy Airport, Queensland, on 5 August 2013

On 5 August 2013, a Cirrus SR22T aircraft, registered VH-LBQ, was being operated on a private flight from Archerfield to Kingaroy, Queensland.

On approach to Kingaroy, at about 500 above ground level (AGL), the pilot extended the flaps and shortly after, disconnected the autopilot (AP). Upon disconnecting the AP, the pilot reported that the aircraft pitched-up violently due to trim runaway. The AP pitch trim was trimming the aircraft for a nose-up position, even though the AP was disconnected. This required the pilot to use a large amount of forward physical force to maintain stable flight. He attempted to resolve the problem by pressing and holding the autopilot disconnect switch (AP DISC), however, this had no effect. The pilot conducted a go-around.

He then used the manual electric trim (MET) hat switch located on the control yoke, in an attempt to trim the aircraft nose-down. The pilot was able to regain sufficient control of the aircraft and land safely at Kingaroy.

On the basis of the evidence available to the ATSB, it was not possible to determine, with any certainty, the reason for the pitch-up event.

This occurrence highlights the safety benefit to be gained from going around, which allowed the pilot time to troubleshoot and prepare for landing with the pitch trim difficulties. This decision helped ensure the aircraft landed safely.

Aviation Short Investigation Bulletin - Issue 26