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KAP 140

A two-axis rate autopilot with altitude preselect. Pitch and roll, no yaw damper, no autothrottle, a 25° bank limit, and a small LCD that tells you exactly what it is doing and nothing more. It was designed for the entry level General Aviation market. To the best of my knowledge, the KAP 140 is not certified for installation in any twin engine aircraft, let alone in a twin engine turboprop of the size of the Twotter.

References

Operation

Power-up runs a real preflight test. On avionics power the unit runs its self-test sequence — about forty seconds, timed against footage of real hardware, not the ~14 s of the stock sim unit. The AP cannot be engaged until PFT completes, and for 30 seconds afterwards the pitch axis is locked out — a blinking red P on the display. The red P is also the G-limit indicator: exceeding roughly +2.0/−0.5 g while engaged locks pitch engagement, and a serious exceedance disconnects the autopilot outright. Pulling avionics power in flight runs a fresh PFT with a longer lockout: the manual warns the accelerometers may need minutes to settle. On a cold start the altitude readout shows dashes until the blind encoder has warmed up, which can take up to three minutes.

Loading into a flight already in progress skips all of this.

Engage in ROL/VS. The AP button engages wing-leveling and holds your current vertical speed — whatever it is. The unit does not level off for you and does not know what you meant; check the VS readout immediately after engaging. Disengaging flashes the AP annunciator for five seconds. The autopilot also lets go on its own if its attitude source dies — a failed or spun-down gyro takes the AP with it.

Info

ROL is not a bank hold mode, it's a wing leveler.

Lateral modes. HDG flies the heading bug; set it before you press the button. When you arm NAV, APR, or REV, the HDG annunciator flashes for five seconds as a reminder that you should use HDG mode to set up the aircraft for intercept. NAV tracks whatever the HSI shows: a VOR radial, a localizer, or — when the CDI source is GPS — the flight plan. REV is the back-course mode: front-course set on the OBS, reverse sensing handled by the unit.

NAV arms until you are established. Press NAV well off the radial and you get NAV ARM: the unit keeps wings level (or your heading, if you keep HDG engaged toward an intercept) until the needle comes alive and the capture criteria hold — then it captures and turns on course. Intercepts beyond about 45° are not recommended, same as the real unit. A capture that never becomes possible — wrong radial, dead receiver — stays armed. With Relaxed NAV arming disabled on the EFB Config tab, arming additionally requires a usable signal at press time, so a press against a dead needle is rejected immediately.

Vertical modes. UP/DN in VS mode: a tap is 100 fpm, holding the button ramps at about 300 fpm per second. ALT holds the altitude at engagement; taps nudge it 20 ft, holding ramps at 500 fpm — the unit stays in ALT while you hold, and the right side of the display shows the target altitude rolling. IAS (our custom addition to the KAP 140) holds airspeed with pitch: taps 5 kt, held ramps 15 kt/s. The rotary knobs set the altitude preselect, shown on the drum above the unit.

Info

Nudging (short UP/DN presses) in ALT HOLD mode changes the altitude hold reference, while the display keeps showing the altitude alerter reference. To see the effect of the nudge, you will have to check the altimeter; there is no feedback on the KAP 140 display.

Altitude preselect. By default the sim's behavior stands: set the preselect, climb or descend at it, and the unit captures. With Realistic altitude arm enabled (EFB Config tab), the unit runs the real two-axis KAP 140's arming lifecycle: only dialing a new preselect while the autopilot is engaged arms it automatically. If you set the altitude before you engage the AP, you will have to arm it yourself.

Altitude alerter. Approaching the preselect, the alert light comes on 1000 ft out and extinguishes at 200 ft; after capture, deviating more than 200 ft flashes it. The alert tone sounds approaching 1000 ft to go and when departing an altitude by 200 ft. Voice callouts are optional.

Voice callouts. According to the manual, the KAP 140 has a few voice callouts which play on the intercom (as opposed to the "beeps" which play over the cockpit speaker). I could not find any reference, so I don't know what they sound like. Consider the present set of samples a placeholder. Two trim warnings are unconditional, the other three messages are optional and whether they play is either decided when the unit is certified for an airframe or when the unit is installed in the airframe (not sure). In the mod, they can be enabled on the EFB Config tab.

  • "Trim in motion" when the autopilot has been running the pitch trim one way for five seconds, and the trim is already well out
  • "Check pitch trim" after fifteen seconds of continuous one way trim, with the PT annunciator flashing an arrow the way the trim is going
  • "Altitude" 1000 ft before the preselect
  • "Leaving altitude" 200 ft after departing it
  • "Autopilot" on disconnect

Warning

The two trim callouts are not notifications, they are warnings telling you that something is wrong.

The voice is currently played simultaneously with the beep altitude alerter beeps and the disconnect signal. Without reference, I cannot say whether that behavior is correct.

BARO. A short press shows the altimeter setting for three seconds so you can adjust it with the knob; holding for two seconds toggles between inches and hectopascals. The preselect logic uses its own blind encoder — your altimeter mis-set is your problem, as in the real installation.

List of changes

  • Capture only when armed, configurable for convenience, faithful to manual — including the manual's automatic arming when a preselect is dialed while the autopilot is engaged.

  • "Vertical Trim"

    • Short presses "nudge" by 20 ft (ALT mode), 100 fpm (VS mode) or 5 kts (FLC), faithful to the manual (except FLC). In VS and FLC, the first press only brings the value up on the display; stepping starts with the second press, as the manual describes.

    • Holding UP/DN initiates a climb/descend at 500 fpm that is maintained until the button is released, faithful to manual. In VS and FLC mode, holding the buttons quickly changes the reference fpm or speed.

  • Pre-Flight Test and initial state

    • Obnoxiously long pre-flight test, based on reference video of a faulty unit, needs validation.

    • A 30s pitch lockout, faithful to manual, apart from the display: a red "P" on display replaces the dedicated warning light which is missing from our visual model.

    • Sticky BARO reminder flashes after the preflight test until the pilot acknowledges by pressing BARO or changing the setting.

  • Voice messages, faithful to the manual: the two standard trim announcements always on, the three optional ones behind a config switch as they are behind an installation option on the real unit.

  • The PT annunciator and its trim-direction arrows now flash on a sustained autopilot trim run, instead of sitting permanently dark.

  • Yaw-Damper (YD) annunciator support.

  • NAV "pre-arm" allows arming NAV prematurely (for example, long before closing in to a VOR radial). While "pre-armed", the NAV ARM flag blinks in a slow rhythm. Configurable as "Relaxed NAV arming".

  • Display shows a "ghost" of the LED elements while not lit.

Known issues

  • The AP still uses the Captain's HSI baro instead of its own.

  • Preflight test plays a disconnect signal instead of a completion chime when it ends, reference needed.

  • The unit engages on a simple press rather than the late-software 0.25s hold, to avoid issues with hardware buttons.

  • The trim announcements only ever fire on autopilot-commanded trim. The real unit watches the electric trim system; the sim reports one trim position and does not say who moved it, so trimming by hand would otherwise set the warnings off.

Reviewed 2026-08-05.