Automatic electric elevator pitch trim is an option, too.ĭriven by the turn coordinator, the KAP140s we have flown perform well and overall reliability is good based on our feedback from long-term owners. The digital KAP140 is rate based and comes in three types: single-axis roll only, dual-axis roll and pitch and dual-axis with altitude preselect using the KEA130A encoding altimeter. The entry level Bendix/King KAP140 is standard equipment on new aircraft including the Cessna singles, but can only be retrofitted to a few aircraft models, with an STC in place for the Piper PA28-181. We recall the wings-and the occupants-of a Malibu shaking during one such descent, with its airspeed needle nudging the red line.
The final test for one autopilot is to rapidly descend the aircraft from altitude to check differences in control cable temperatures. As manufacturers insist, a flight control system installation is not work for amateurs because its airframe and avionics intensive and can require precise tuning and alignment through flight testing, which can include scary levels of risk. Still, on any airframe, regardless of the attitude reference source, an autopilots performance is directly proportional to control cable tensions and other interface considerations. Rate-based autopilots have one big advantage over attitude-based autopilots: Theyre usually cheaper to buy and install.
Which type is better for commanding an autopilot? Based on our experience, most small airframes are well matched to a rate-based system while heavier, higher-performance airplanes are better off with an attitude system, especially when flying at higher speeds. As one would expect, the attitude gyro often offers a more precise reference that results in a smoother ride, as long the gyro stays healthy.
An attitude-based autopilot receives its roll and pitch reference signal from the attitude gyro, while a rate-based autopilot listens to a rate gyro inside a turn coordinater. To do this, an autopilot needs an attitude reference and this is generated by a gyroscope, or more recently, through solid-state electronics.Īutopilots should be considered stability control systems since they correct the flight path when the airplane departs from it, say in turbulent air or due to transient mistrim. The driving goal for autopilots is to fly the airplane better than the pilot can-no altitude excursions, no wandering off the approach centerline and no heading bobbles, all while keeping the passengers out of the barf bags. The choices are relatively few, based on STC approvals, except when shopping the Meggitt/S-TEC line, which seems to have an autopilot for every aircraft model. In this article, well examine the current popular market offerings in autopilot and flight control systems for light airplanes. No surprise that such automation isnt cheap.īut repairing older systems doesnt come cheap either and the line needs to be drawn on whether to nurse along an old autopilot or rip it out in favor of a new model. Theyll fly GPS flightplans in the horizontal and vertical, climbing, descending and leveling the airplane and some even fly oval tracks in holding, all while providing voice prompts to keep the pilot in the loop. Modern autopilots compliment the capabilities of nav management systems such as Garmins gold standard 430/530 series. Still, we cant think of many upgrades that more enhance safety, airframe value and utility. While many new autopilots will precisely fly the airplane from wheels up to the landing flare, their costs could exceed the value of the airframe.
#STEC 50 AUTOPILOT PITCH PROBLEMS UPGRADE#
Clearly, the most expensive upgrade to an airframe is the retrofit of a new autopilot.