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Here are answers to frequent questions we receive.


Can I use your autopilot products in my certified airplane?

No.  Our autopilots are intended to be used in experimental, warbird and LSA aircraft only.  (UPDATE):  The Pro Pilot is currently in the STC'ed and approved for many certified aircraft.

Is there a performance difference between the Pro Pilot and your other individual autopilot and altitude control systems?

No.  The performance of the Pro Pilot will be equal to the superior performance of the EZ Pilot autopilot and the EZ-3 altitude control system.  However, the Pro Pilot takes less panel space and offers the opportunity for GPSS, GPSV, Fuel Management and other optional features.  However, only the Pro Pilot can be upgraded to include GPSS/GPSV when it will be used in conjunction with an approach certified GPS receiver or selected EFIS systems. 

I already have a Navaid servo installed in my aircraft.  Will your autopilots work with it?

Yes, the EZ Pilot is 100% compatible with the Navaid servo for aileron control.  If you already have one, you may purchase the EZ Pilot control head and a jumper cable (to interface with your existing aircraft autopilot wiring) for $1,120.00.  The Pro Pilot can also use the Navaid aileron servo but you will need to replace the electrical harness.

Is your autopilot a "turn coordinator" type?

The autopilot products use solid-state MEMS gyros as a reference, and the implementation is somewhat analogous to a turn coordinator, but it has much better dynamic response than a mechanical gyro.  Its performance in turbulence so closely matched that of the 2-gyro systems that we developed and tested that we concluded any benefit of a second gyro did not justify the additional cost.  The response of the MEMS gyro must be experienced to be believed.  The Pro Pilot uses two MEMS gyros.

Do the autopilots have a turn coordinator display?

Yes, a turn coordinator display can be selected.  (See a photo)

Are panel mounted GPS receivers recommended over handheld receivers when used as a reference for autopilots?

Many handheld GPS receivers update and provide output data (NMEA 0183) only once every two seconds (newer models - every second).  Panel mount receivers update and provide output data (Aviation Data Link) at least once per second.  Therefore, panel mount receivers talk to the autopilot at least twice as often and provide it with more current position and situational data.  It follows, then, that the autopilot will be somewhat more responsive when coupled to a panel mounted GPS.  In most cases, when closely tracking the course centerline, you will not notice any difference.  However, if you are turning at a 3 degree per second rate the aircraft can turn 6 degrees between updates if you are using a handheld GPS.  One place this may be noticeable  is in the PCS (Pilot Command Steering) mode - i.e., If you engage PCS, enter a steep turn and then release the button, it is possible to have several degrees of overshoot if you don't level the plane and wait for the next GPS update before releasing the button.  There are predictive anticipation algorithms incorporated into the EZ Pilot system that significantly reduce these inaccuracies, but some overshoot may still occur.  Pilots will rarely notice any difference in autopilot performance when comparing panel mount to handheld GPS receivers.

If GPSS and/or GPSV is desired for the Pro Pilot, a panel mounted GPS receiver (or a compatible EFIS system) will be required.  A WAAS approved panel mount is required to track vertical RNAV (LPV) descents.

A complete list of compatible GPS receivers is here.

Will aggressive or aerobatic maneuvers "confuse" the solid-state gyros?

In conventional gyro systems, it is possible to "tumble" the gyro if you engage in aggressive maneuvers or aerobatics.  These systems then need some time in level flight to re-orient themselves.  Solid state gyros are considerably different in nature, but can still be caused to experience some drift by sustained aggressive maneuvers.  They will then need access to a reference (such as a GPS signal) or some "quiet time" in level flight to get reoriented.  They are different in that they do not sense gravity, so the system processes GPS data for the gyro to use as a reference. If you turn your servo off and do aerobatics or several tight turns, it will quickly reorient to a GPS signal and pull in to the selected course when you re-engage the servo.

What happens if I lose GPS signals?

While this is extremely unlikely when using a good GPS receiver with an external antenna, the autopilot will still keep the wings level for an extended period of time.  The gyro is heavily compensated for drift and temperature changes.  If, after several minutes of GPS loss, the pilot notices a slight change in heading, a brief adjustment of the turn coordinator roll trim control will stop it.  The autopilot will also continue to compensate for turbulence-induced roll movements. Once a GPS signal is reestablished the autopilot will resume tracking the flight plan.

Do your autopilots work with all GPS receivers?

Although aviation GPS receivers are generally supposed to conform to industry standards (NMEA 0183 for portables and Aviation Data Link for most panel mount receivers) they do vary in the format of the output data stream.  This is especially true for older systems.  Some do not put out enough information for autopilot navigational purposes, as they were designed before it was realized that such outputs could be useful to other devices.  Our autopilots are compatible with most popular aviation GPS receivers.  The system scans, analyzes and configures the data so it is useful for autopilot navigation.  If your receiver does not provide data that the system recognizes, it will present the message "No GPS".  You should notify the factory if you cannot sync to the signal.  However, it is important to first check for the following:

        a.  Your GPS probably has a setup mode where you must enable the output.  Some have several possible output modes.  The proper mode must be enabled for the GPS to communicate with the autopilot.  For the NMEA format the desired output is NMEA 0183, Rev 2.0 (or greater), 4800 or 9600 baud rate, 8 data bits, no parity, 1 stop bit (8, N, 1).  The AVLINK is 9600, 8 data bits, no parity, 1 stop bit (8, N, 1).
        b.  You must be in an area of good signal strength for your GPS receiver to operate properly.  If you try to use it in a hangar, for instance, the weak signals will not provide reliable data and the "No GPS" message will appear.
        c.  For reliable operation, you will probably need to employ an external antenna for your GPS (strongly recommended).  Or, if using a portable GPS and you don't have an external antenna, you must mount the GPS where the antenna has a clear "view" of the sky in all directions.  Even a GPS enabled autopilot has to be able to see where it's going.

What safety features are incorporated in the roll (aileron) servo?

While the control head is the brains of the system, the servo is the muscle.  Because the servo is attached to one of the most important parts of the airplane (the ailerons), and because it is capable of so much strength (torque), there must be several ways for the pilot to overcome it if necessary. 
         First, there is a solenoid in the servo that, when engaged, pulls internal gears together to connect the motor to the ailerons.  When the solenoid is not engaged, the controls are free and easily movable.  We provide three ways to disconnect the roll servo:
            a.  Press the Remote Servo Disconnect button on the control stick.
            b.  Press the SERVO button on the EZ Pilot control head (H NAV button on the Pro Pilot).
            c.  Turn the system off with the Power Switch on the control head.
        Second, there is an internal clutch that will slip when a moderate (adjustable) force is applied to the control stick.  In an emergency, such as abrupt severe turbulence, it is easy to overcome the servo and manipulate the ailerons.
        Third, the solenoid pulls the gears together with substantial force, but if for some reason the clutch should fail (has never happened to our knowledge), putting more pressure on the control stick will overcome the solenoid pressure and force the gears apart.  The solenoid pull-in force has been designed to allow the gears to slip with a moderate control force input.
        Fourth, although this feature is in the control head, if you inadvertently engage the servo on the ground prior to takeoff the autopilot will detect this and automatically disconnect the servo at 25 knots during your takeoff roll (assuming your GPS is on and properly acquiring satellites).

Altitude Hold Systems

Can the EZ series altitude hold systems be used independent of the EZ Pilot autopilot?

Yes, the EZ- 3 is designed to be independent systems that can be used with any wing leveler or horizontal attitude autopilot.  However, it is recommended that you seriously consider connecting your "quick disconnect" button to both systems so that you can easily disconnect them in an emergency (oncoming traffic, severe turbulence, etc.).  When using Trio products, the quick disconnect button also enables the Pilot Command Steering (PCS) function, which is a very desirable feature of each system.

The Pro Pilot contains all of the altitude control features of the EZ-3, plus an optional upgrade for GPSV (vertical guidance from WAAS enabled GPSV receivers and compatible EFIS systems)

Why is a gyro used in the altitude hold system?

While the internal pressure transducer (altitude sensor) directs the system to hold the proper altitude, the gyro provides the principal reference for pitch stability.  Because of the superb dynamic response of the MEMS gyro, it handles turbulence with ease.

Why do you use a "G force" monitor (accelerometer)?

Because we are, above all, concerned with safety.  If you are going to connect a servo system to your elevators, we believe that it is essential to limit the vertical acceleration that an altitude control system might induce.  Should you encounter a strong downdraft or updraft, you don't want a system that will pull excessive "G's" to maintain altitude when it could damage the aircraft wings - or worse.  The accelerometer system is designed to sound an alarm and disconnect the controls whenever it senses a sustained vertical acceleration (positive or negative) of about 1 G from normal.  Anything beyond this is an extraordinary circumstance that dictates that you, the pilot, should be in control of the aircraft.  Because sharp turbulence can often exceed 1 G, the system integrates brief excursions caused by light-to-moderate turbulence and does not disconnect.  Moderate-to-severe turbulence will cause the integration level to rise and it will then sound the alarm and release the controls to the pilot.

How does the "Fine Altitude" control work?

When the altitude hold (Alt Hold) is engaged the pilot may elect to adjust the altitude in small increments, by rotating the encoder knob.  Altitude change will be a little over 5 feet per "click" of the encoder control.  This feature can be quite useful when flying cross country and getting frequent updates to barometric pressure changes.  It allows small altitude changes without the necessity of disengaging the system, flying to a new altitude, and re-engaging the system.  If the knob is rotated rapidly, the system will limit altitude change (up or down) to about 100 feet per minute.

What is the "Heartbeat" monitor?

There are several microprocessors in Trio altitude systems.  They are there to provide control functions but, equally important, each one is constantly monitoring the performance of the other processors.  In the communication stream from each processor there is a "heartbeat" signal.  If any processor in the system detects an interruption of the heartbeat signal, it will immediately trigger an event that will sound an audio alarm and disconnect the altitude hold system from the elevator control.  Because the servo is the device that is actually connected to the elevator controls, it contains an additional "supervisory processor," whose only function is to monitor all communication from the servo processor and the other two processors in the system.  If it detects any anomalies in the data from any of them, it will command an immediate servo release from the elevator control system. 

How does the LCD switch work on the EZ series altitude control systems?

The switch itself is a simple momentary push button switch.  However, it has a versatile LCD display screen incorporated into the front surface of the switch.  This functions as an annunciation screen and a graphics display.  It allows the altitude hold controller module to present pertinent data to the pilot in the form of information, warnings and alarms.

How is the "Gold Standard" servo different from other servos?

You can see a feature list here.

Auto-Trim?  What is Auto-Trim?

Let's say that you command a climb using the Pro Pilot, or EZ-3.  The system will tell the servo to pull the elevator up.  To do this requires a continuous force on the elevator controls because the aircraft trim is set for level flight.  With Auto-Trim, the control head senses when trim is required and sends that information to the servo.  The servo contains drive circuits that will command your aircraft electric trim to relieve the pressure on the control system and it will drive the trim motor until the aircraft is trimmed for climb.  Once you reach the desired altitude and the aircraft levels off, the aircraft will once again be out of trim.  The Auto-Trim will again command the aircraft electric trim system to adjust for proper level-flight trim.

Why would I want Auto-Trim?

Auto-Trim can be important because, with the Altitude Control servo operating the elevator, you don't have a "feel" for where the trim is set.  Without an Auto-Trim system you might get a big surprise when you disconnect the Altitude Control system.  If the airplane has been out of trim while the Altitude Control was handling the elevator you may experience an abrupt pitch change when releasing the servo.  With Auto-Trim you don't have to worry about it, as the Auto-Trim system will keep the aircraft in proper trim during climbs, descents, and level flight - it's one less thing you have to fuss with.  (Note: when Auto-Trim is not installed, the altitude control system will still alert the pilot that trim is required by a small flashing arrow on the display screen).