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Control Rigging: Critical, Yet Forgotten

That's an autopilot pitch servo in the tail of a Piper. Premature servo motor failure - and sloppy autopilot performance - is often a direct result of incorrect cable tensions. Take it to a shop that has manuals, tools and experience to rig it the correct way.

Who has been working on this airplane? That was the question we would often ask in the shop when an airplane would come in for autopilot troubleshooting and we found control cable tensions so low you could strum a tune with them. Oftentimes it was to troubleshoot pitch and roll problems where the autopilot would deviate from the selected altitude or blow through the desired course. Then there were pilots who would complain the airplane wasn’t making book speeds, the controls weren’t as responsive as they once were, or the airplane wouldn’t fly straight and level. All are symptoms of rigging problems.

Owners give it little thought, and it’s a maintenance item that should be checked during annual inspection, but it often gets dropped. Moreover, when faced with the hefty shop labor to properly rig the airplane the way the manufacturer’s maintenance manual prescribes, many owners put it off. That’s a bad idea, especially when investing in a new autopilot. Read on for a lesson in control rigging 101. 

Larry Anglisano

Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.