FAQ
Find answers to our most frequently asked questions below. Before contacting us through our support service, please check here to see if you can find a solution to your problem.
Installation & Configuration Section
This information pertains to all Flybox products equipped with CAN bus ports.
If you are not familiar with CAN bus connections, you may have made some mistakes in connecting the cables or termination resistors. The most common mistakes we have encountered are:
- Inversion of the H and L signals, please check again.
- The 2 termination resistors to be installed on a CAN line are 120 Ohms each, so the total resistance on a CAN line at the end of the installation should always be around 60 ohms, a value easily measurable with an ohmmeter. If resistors with an incorrect value are installed or if they are not installed at all, the value will be different from 60 ohms and CAN communication will likely not work for all devices connected to the same CAN line.
- In the case of Rotax iS engines, or other engines equipped with an ECU, there are typically 2 separate CAN lines. Sometimes the correct resistors are properly installed on each CAN line, but then the two lines are connected in parallel to connect to some types of EFIS that have a single CAN input; this reduces the total termination resistance to very low values, such as 30 ohms, and for this reason, there may be no data exchange on the CAN line. It is therefore good practice to check the resistance value on the CAN line with the connections completed and the equipment turned off.
Click the button on the right to view a brief guide.
If you are not familiar with CAN bus connections, you may have made some mistakes in connecting the cables or termination resistors. The most common mistakes we have encountered are:
- Inversion of the H and L signals, please check again.
- The 2 termination resistors to be installed on a CAN line are 120 Ohms each, so the total resistance on a CAN line at the end of the installation should always be around 60 ohms, a value easily measurable with an ohmmeter. If resistors with an incorrect value are installed or if they are not installed at all, the value will be different from 60 ohms and CAN communication will likely not work for all devices connected to the same CAN line.
- In the case of Rotax iS engines, or other engines equipped with an ECU, there are typically 2 separate CAN lines. Sometimes the correct resistors are properly installed on each CAN line, but then the two lines are connected in parallel to connect to some types of EFIS that have a single CAN input; this reduces the total termination resistance to very low values, such as 30 ohms, and for this reason, there may be no data exchange on the CAN line. It is therefore good practice to check the resistance value on the CAN line with the connections completed and the equipment turned off.
Click the button on the right to view a brief guide.
This applies to all Flybox instruments that have the fuel level indication function (not to be confused with the fuel computer).
- The result you obtain after calibration may be correct. Remember that when the message "small variation in mV" appears during calibration, the fuel just added will not be counted. Therefore, in this case, we recommend that you read and understand the relevant section of the instrument manual carefully. Remember that if, for example, you put in 5 liters 3 times and for all these 3 times you see the message "small millivolt change," 15 liters will be deducted from the total amount you will put in the tank.
This happens because, if the instrument is unable to measure that quantity, it is completely natural that it cannot provide you with information regarding it at that position of the sensor.
- The result you obtain after calibration may be correct. Remember that when the message "small variation in mV" appears during calibration, the fuel just added will not be counted. Therefore, in this case, we recommend that you read and understand the relevant section of the instrument manual carefully. Remember that if, for example, you put in 5 liters 3 times and for all these 3 times you see the message "small millivolt change," 15 liters will be deducted from the total amount you will put in the tank.
This happens because, if the instrument is unable to measure that quantity, it is completely natural that it cannot provide you with information regarding it at that position of the sensor.
This information applies to all Flybox products that display CHT, CT (coolant temperature), and oil temperature readings and are connected directly to the engine’s sensors, such as those for the Rotax 912 and 914 models.
These engines do not have a CAN bus from which to read the information, therefore probes are used. These probes are usually connected to ground through their metal body and have a single wire that goes to the instrument. This means that the measurement is referenced to the engine's ground. Check if, in the wiring diagram provided in the instrument manual, the probe input is of the "differential" type; this can be understood from the fact that that input consists of 2 pins; in that case, the other pin of that input must be connected to the same ground of the engine or to the instrument's GND. These details are always highlighted in the manuals.
These engines do not have a CAN bus from which to read the information, therefore probes are used. These probes are usually connected to ground through their metal body and have a single wire that goes to the instrument. This means that the measurement is referenced to the engine's ground. Check if, in the wiring diagram provided in the instrument manual, the probe input is of the "differential" type; this can be understood from the fact that that input consists of 2 pins; in that case, the other pin of that input must be connected to the same ground of the engine or to the instrument's GND. These details are always highlighted in the manuals.
This applies to all Flap Controller models, EFC-P, EFC-Plus, Air-EFCF.
The procedure is well described in the manual; in any case, here we outline the main reasons for calibration failure by users.
- Before entering the position programming, it is always necessary to position the flap in an intermediate position relative to the limit switches; this can also be done before programming the positions by setting the switch to "MANU", otherwise it will be impossible to enter programming.
- If it is only possible to move the flap position manually, there is a chance that the programming of the positions did not succeed, try repeating it.
- If the error can be diagnosed by the instrument, the LEDs will flash according to a specific code to help identify the type of problem. Refer to the instrument manual for an explanation of possible errors.
The procedure is well described in the manual; in any case, here we outline the main reasons for calibration failure by users.
- Before entering the position programming, it is always necessary to position the flap in an intermediate position relative to the limit switches; this can also be done before programming the positions by setting the switch to "MANU", otherwise it will be impossible to enter programming.
- If it is only possible to move the flap position manually, there is a chance that the programming of the positions did not succeed, try repeating it.
- If the error can be diagnosed by the instrument, the LEDs will flash according to a specific code to help identify the type of problem. Refer to the instrument manual for an explanation of possible errors.
This applies to all instruments equipped with an embedded magnetometer.
The instrument you are about to install features a state-of-the-art embedded magnetometer. This sensor acts as a highly sensitive electronic compass, reading the Earth's weak magnetic field to provide you with a precise and smooth heading indication during flight.
Due to its high sensitivity, the magnetometer can easily be "tricked" by elements inside or near the instrument panel. Seemingly harmless objects can generate permanent or temporary local magnetic fields that are stronger than the Earth's magnetic field, causing heading errors.
To achieve maximum performance and prevent incorrect readings, it is essential to consider the following key factors during placement and mounting:
1. Ferrous Materials and the Keep-Out Zone.
Standard steel screws, iron mounting brackets, airframe structures, or firewall hinges often possess significant residual magnetism.
Golden Rule: Keep the instrument at least 15-20 cm (6-8 inches) away from any ferrous objects or other avionics (such as radios, transponders, or displays) that contain internal magnets or coils.
Mandatory Hardware: Use strictly non-magnetic hardware (e.g., brass or non-magnetic stainless steel like AISI 316) to secure the instrument to the panel. A single standard iron screw is enough to magnetize the mounting area and distort the sensor's readings.
2. Electrical Wiring and Electromagnetic Fields.
Whenever electrical current flows through a wire, it generates a magnetic field proportional to the current's intensity. Wires powering heavy loads (landing lights, electric pumps, radios) are the primary cause of sudden heading shifts when those systems are turned on.
Golden Rule: Maintain a minimum distance of 20-30 cm (8-12 inches) from power cables, alternators, engine magnetos, and circuit breakers. Whenever possible, twist the positive and negative power wires together (twisting cancels out and drastically reduces the emitted magnetic field).
3. The "Compass Test" (Empirical Check Before Drilling).
Before drilling permanent holes in your instrument panel, perform this simple test:
Take a standard analog card compass (or use a smartphone compass app) and place it on the exact spot on the panel chosen for the instrument.
Turn the aircraft’s master switch and various electrical loads (radios, lights, etc.) on and off.
If the compass needle deflects or moves, that specific location is subject to magnetic interference, and you must select an alternative position.
4. Mandatory Ground Calibration (Compass Swing).
The instrument's software algorithm compensate for the small, unavoidable, and fixed magnetic anomalies of the aircraft. Post-installation calibration is not optional, it is a mandatory step.
Calibration performed according to the instructions in the instrument manual cannot magically eliminate interference if the instrument is positioned too close to strong magnetic sources
The instrument you are about to install features a state-of-the-art embedded magnetometer. This sensor acts as a highly sensitive electronic compass, reading the Earth's weak magnetic field to provide you with a precise and smooth heading indication during flight.
Due to its high sensitivity, the magnetometer can easily be "tricked" by elements inside or near the instrument panel. Seemingly harmless objects can generate permanent or temporary local magnetic fields that are stronger than the Earth's magnetic field, causing heading errors.
To achieve maximum performance and prevent incorrect readings, it is essential to consider the following key factors during placement and mounting:
1. Ferrous Materials and the Keep-Out Zone.
Standard steel screws, iron mounting brackets, airframe structures, or firewall hinges often possess significant residual magnetism.
Golden Rule: Keep the instrument at least 15-20 cm (6-8 inches) away from any ferrous objects or other avionics (such as radios, transponders, or displays) that contain internal magnets or coils.
Mandatory Hardware: Use strictly non-magnetic hardware (e.g., brass or non-magnetic stainless steel like AISI 316) to secure the instrument to the panel. A single standard iron screw is enough to magnetize the mounting area and distort the sensor's readings.
2. Electrical Wiring and Electromagnetic Fields.
Whenever electrical current flows through a wire, it generates a magnetic field proportional to the current's intensity. Wires powering heavy loads (landing lights, electric pumps, radios) are the primary cause of sudden heading shifts when those systems are turned on.
Golden Rule: Maintain a minimum distance of 20-30 cm (8-12 inches) from power cables, alternators, engine magnetos, and circuit breakers. Whenever possible, twist the positive and negative power wires together (twisting cancels out and drastically reduces the emitted magnetic field).
3. The "Compass Test" (Empirical Check Before Drilling).
Before drilling permanent holes in your instrument panel, perform this simple test:
Take a standard analog card compass (or use a smartphone compass app) and place it on the exact spot on the panel chosen for the instrument.
Turn the aircraft’s master switch and various electrical loads (radios, lights, etc.) on and off.
If the compass needle deflects or moves, that specific location is subject to magnetic interference, and you must select an alternative position.
4. Mandatory Ground Calibration (Compass Swing).
The instrument's software algorithm compensate for the small, unavoidable, and fixed magnetic anomalies of the aircraft. Post-installation calibration is not optional, it is a mandatory step.
Calibration performed according to the instructions in the instrument manual cannot magically eliminate interference if the instrument is positioned too close to strong magnetic sources
This applies to all instruments that have the Altimeter function.
All the Altimeter sensors are calibrated at the factory at the time of manufacturing. Over the years it may be necessary to do the offset recalibration that can be done by the user in a simple way.
For a detailed description of how to activate the procedure, refer to the manual of the instrument for Omnia Alti-Vario, Eclipse NG, SkySense. Typically, the section explaining the procedure is called "Adjust Offset" or "mBar Offset".
For the Oblò, Oblò2, Eclipse instruments, the procedure is carried out after entering a password that must be requested from Flybox.
Perform this procedure if you notice differences compared to a reference altimeter only.
All the Altimeter sensors are calibrated at the factory at the time of manufacturing. Over the years it may be necessary to do the offset recalibration that can be done by the user in a simple way.
For a detailed description of how to activate the procedure, refer to the manual of the instrument for Omnia Alti-Vario, Eclipse NG, SkySense. Typically, the section explaining the procedure is called "Adjust Offset" or "mBar Offset".
For the Oblò, Oblò2, Eclipse instruments, the procedure is carried out after entering a password that must be requested from Flybox.
Perform this procedure if you notice differences compared to a reference altimeter only.
This applies to all instruments that have a USB port that can be used to perform firmware updates, save and restore settings, save logs, or other operations.
- Generally, our instruments recognize USB flash drives formatted in FAT32 and that are no larger than 2GB.
- The interested files must always be present in the root of the USB stick and not contained in folders.
- The USB stick should be free of other files; it is recommended to keep a USB stick always empty to use for Flybox instruments. In case of problems, keep in mind that Flybox provides tested and 100% compatible USB sticks at a symbolic price.
- Generally, our instruments recognize USB flash drives formatted in FAT32 and that are no larger than 2GB.
- The interested files must always be present in the root of the USB stick and not contained in folders.
- The USB stick should be free of other files; it is recommended to keep a USB stick always empty to use for Flybox instruments. In case of problems, keep in mind that Flybox provides tested and 100% compatible USB sticks at a symbolic price.
This applies to all instruments equipped with analog inputs for sensors, such as those for temperature and pressure.
If a sensor is connected to more than one instrument, it is possible that both instruments read incorrect values since each instrument reads the sensor's value in parallel with the impedance of the other instrument; therefore, the operation of connecting two instruments in parallel to the same sensor is always discouraged.
This does not apply to all sensors but especially those that have a current output like the Rotax oil pressure (4-20mA), voltage outputs with low power like J or K thermocouples, sensors with resistive output like fuel senders and oil temperature. In case of doubts, please ask us before conducting experiments that may yield incorrect results or damage the instrument.
If a sensor is connected to more than one instrument, it is possible that both instruments read incorrect values since each instrument reads the sensor's value in parallel with the impedance of the other instrument; therefore, the operation of connecting two instruments in parallel to the same sensor is always discouraged.
This does not apply to all sensors but especially those that have a current output like the Rotax oil pressure (4-20mA), voltage outputs with low power like J or K thermocouples, sensors with resistive output like fuel senders and oil temperature. In case of doubts, please ask us before conducting experiments that may yield incorrect results or damage the instrument.
Troubleshooting Section
The first thing to check is whether the electronic MOSFET bridge output is operational.
To perform the test, follow this sequence:
- on the ground and the engine not running, set the switch to "Manual".
- lower the right switch (RPM DEC) until reaching the maximum pitch of the propeller.
- reposition the red switch to "Constant Speed".
- the propeller pitch should automatically move to the minimum pitch.
If it does not move, it means that the output is burnt out and the Controller needs to be sent for repair.
To perform the test, follow this sequence:
- on the ground and the engine not running, set the switch to "Manual".
- lower the right switch (RPM DEC) until reaching the maximum pitch of the propeller.
- reposition the red switch to "Constant Speed".
- the propeller pitch should automatically move to the minimum pitch.
If it does not move, it means that the output is burnt out and the Controller needs to be sent for repair.
Below we summarize a list of cases encountered over the years, separated by type of propellers.
Electric propellers equipped with slip ring distributors:
- Check the wear of the brushes, the compression of the springs that push them against the tracks, and the state of oxidation and cleanliness of these. It may happen that a defective contact issue does not properly transmit current to the propeller motor.
- The propeller's gear motor is installed at the center of the hub and rotates with the propeller. There have been cases where, at high speeds, the centrifugal force causes the brushes of the DC motor to move away, interrupting the current. Contact the propeller manufacturer for a solution to this issue.
- If the time for the propeller to go from minimum pitch to maximum pitch exceeds 3 or 4 seconds, it is possible that applying power too quickly may cause the RPM limit to be exceeded, resulting in an over-rev alarm from the instrument that manages the engine. This is not a malfunction of the PR1-P instrument but a limitation of the propeller that changes pitch too slowly compared to the throttle actuation speed.
Electric-hydraulic propellers equipped with a pump and oil transmission through the hollow shaft of the gearbox:
- If there is an air bubble in the oil circuit, it is possible that the system will oscillate or not regulate properly. In this case, remove the air from the circuit. Air is compressible, so before achieving a change in the angle of the blades, it must be fully compressed and then movement will occur. This delay, which will be proportional to the amount of air in the system, will introduce a delay that will cause the RPM to oscillate as a consequence.
- In both models of propellers described above, in the event of a total lack of adjustment, it is necessary to check if the instrument correctly reads the RPM. To do this, simply read the number in the top right corner of the display, which represents the current RPM in real-time. If these do not match the RPM read on the main tachometer, it is necessary to check if the signal from the pickup is reaching the instrument.
Electric propellers equipped with slip ring distributors:
- Check the wear of the brushes, the compression of the springs that push them against the tracks, and the state of oxidation and cleanliness of these. It may happen that a defective contact issue does not properly transmit current to the propeller motor.
- The propeller's gear motor is installed at the center of the hub and rotates with the propeller. There have been cases where, at high speeds, the centrifugal force causes the brushes of the DC motor to move away, interrupting the current. Contact the propeller manufacturer for a solution to this issue.
- If the time for the propeller to go from minimum pitch to maximum pitch exceeds 3 or 4 seconds, it is possible that applying power too quickly may cause the RPM limit to be exceeded, resulting in an over-rev alarm from the instrument that manages the engine. This is not a malfunction of the PR1-P instrument but a limitation of the propeller that changes pitch too slowly compared to the throttle actuation speed.
Electric-hydraulic propellers equipped with a pump and oil transmission through the hollow shaft of the gearbox:
- If there is an air bubble in the oil circuit, it is possible that the system will oscillate or not regulate properly. In this case, remove the air from the circuit. Air is compressible, so before achieving a change in the angle of the blades, it must be fully compressed and then movement will occur. This delay, which will be proportional to the amount of air in the system, will introduce a delay that will cause the RPM to oscillate as a consequence.
- In both models of propellers described above, in the event of a total lack of adjustment, it is necessary to check if the instrument correctly reads the RPM. To do this, simply read the number in the top right corner of the display, which represents the current RPM in real-time. If these do not match the RPM read on the main tachometer, it is necessary to check if the signal from the pickup is reaching the instrument.
This applies to all Flybox instruments that have the fuel pressure indication function (not to be confused with the fuel computer).
If the instrument indicates a pressure that is lower than normal on certain occasions, for example when you give power to the engine for takeoff, you are advised to check with your maintenance mechanic the actual state of pressure in the system. Most of the time this happens, it is a symptom of a real problem; in fact, the instrument cannot know if the engine is running at low or high RPM, so a low fuel pressure indication is information to be taken seriously. It is not enough to think that the culprit is the instrument; it does not know what the engine is doing.
If the instrument indicates a pressure that is lower than normal on certain occasions, for example when you give power to the engine for takeoff, you are advised to check with your maintenance mechanic the actual state of pressure in the system. Most of the time this happens, it is a symptom of a real problem; in fact, the instrument cannot know if the engine is running at low or high RPM, so a low fuel pressure indication is information to be taken seriously. It is not enough to think that the culprit is the instrument; it does not know what the engine is doing.
This information applies to all Flybox products that display EGT information.
To read the EGT temperatures, K-type thermocouples are always used. All commercially available K-type thermocouples, if functioning correctly, send the same type of signal that is interpreted and converted into a numerical indication by our instruments that have this function.
The terminals of K thermocouples are polarized, which means they cannot be reversed. The wires of K probes usually do not reach the instrument because they are short, so they need to be extended with a special cable that is made with the same metals as the thermocouple. To connect this cable, connectors that are also compensated are usually used. Each of these components must be connected without errors to the instrument. If there is an error, it will affect the accuracy of the reading. If a connection like the one described is made, it is therefore important to respect the polarities of the probe, connectors, and cables. The latter can have various colors according to different European standards or those from other parts of the world. For example, we provide here the diagram with the color references of the materials supplied by Flybox in the standard kit.
To read the EGT temperatures, K-type thermocouples are always used. All commercially available K-type thermocouples, if functioning correctly, send the same type of signal that is interpreted and converted into a numerical indication by our instruments that have this function.
The terminals of K thermocouples are polarized, which means they cannot be reversed. The wires of K probes usually do not reach the instrument because they are short, so they need to be extended with a special cable that is made with the same metals as the thermocouple. To connect this cable, connectors that are also compensated are usually used. Each of these components must be connected without errors to the instrument. If there is an error, it will affect the accuracy of the reading. If a connection like the one described is made, it is therefore important to respect the polarities of the probe, connectors, and cables. The latter can have various colors according to different European standards or those from other parts of the world. For example, we provide here the diagram with the color references of the materials supplied by Flybox in the standard kit.
This applies to all Flybox instruments that have a Tachometer.
- In the Rotax 912, 912ULS, 914 engines, the signal that goes to our instruments comes directly from the pick-up. Since the pick-up has 2 wires, it means that one goes to our instrument, while the other must be connected to GND; make sure it is connected.
This is the detail for connecting the Rotax 914 TCU: Connect Pin 13 of the TCU to the instrument input, Connect Pin 26 of the TCU to any GND.
In the case of the Vigilus and EngiMaster instruments, it will also be necessary to adjust the signal reading threshold from the appropriate menu, so that it accurately reads the RPM at all regimes.
In the case of engines connected to the instrument via CAN bus, a failure to read the RPM may be due to incorrect CAN bus connection (see the specific FAQ) or incorrect selection of the engine type in the instrument setup.
- In the Rotax 912, 912ULS, 914 engines, the signal that goes to our instruments comes directly from the pick-up. Since the pick-up has 2 wires, it means that one goes to our instrument, while the other must be connected to GND; make sure it is connected.
This is the detail for connecting the Rotax 914 TCU: Connect Pin 13 of the TCU to the instrument input, Connect Pin 26 of the TCU to any GND.
In the case of the Vigilus and EngiMaster instruments, it will also be necessary to adjust the signal reading threshold from the appropriate menu, so that it accurately reads the RPM at all regimes.
In the case of engines connected to the instrument via CAN bus, a failure to read the RPM may be due to incorrect CAN bus connection (see the specific FAQ) or incorrect selection of the engine type in the instrument setup.
When connecting an external GPS to a Flybox instrument, two aspects need to be considered:
- the transmission speed (baud rate) of the 2 devices must be set to the same value on both (the default value of the Flybox GPS receiver is fixed at 9600).
- Connecting a Flybox instrument to an external navigator requires setting the minimum NMEA183 sentences as specified in the instrument's manual. Therefore, refer to the manual of the instrument you are installing.
Another aspect that should not be overlooked is the time of the first FIX, which, under unfavorable sky visibility conditions, such as in hangars or in case of poor installation, for example near posts that obstruct the view of the sky, can take many minutes.
Also pay attention to the GND, which must be the same for the 2 interfaced devices.
The Flybox tools always have a menu where you can check the arrival of signals from the GPS receiver; refer to the relevant manual for more information regarding the GPS verification menu.
- the transmission speed (baud rate) of the 2 devices must be set to the same value on both (the default value of the Flybox GPS receiver is fixed at 9600).
- Connecting a Flybox instrument to an external navigator requires setting the minimum NMEA183 sentences as specified in the instrument's manual. Therefore, refer to the manual of the instrument you are installing.
Another aspect that should not be overlooked is the time of the first FIX, which, under unfavorable sky visibility conditions, such as in hangars or in case of poor installation, for example near posts that obstruct the view of the sky, can take many minutes.
Also pay attention to the GND, which must be the same for the 2 interfaced devices.
The Flybox tools always have a menu where you can check the arrival of signals from the GPS receiver; refer to the relevant manual for more information regarding the GPS verification menu.
Some of our instruments have updatable firmware via USB pen drive; this FAQ refers to all these instruments.
Most instruments do not have an operating system, so they are unable to work with all the USB drives on the market. The ideal USB drive is a maximum of 2 GB, FAT32 formatted, and free of files and folders. We offer tested USB pen drives with all our instruments at a symbolic price, which work seamlessly for saving parameters, LOGs, and performing firmware updates.
The non-compliance with these characteristics makes the pen drive unusable with our instruments.
Most instruments do not have an operating system, so they are unable to work with all the USB drives on the market. The ideal USB drive is a maximum of 2 GB, FAT32 formatted, and free of files and folders. We offer tested USB pen drives with all our instruments at a symbolic price, which work seamlessly for saving parameters, LOGs, and performing firmware updates.
The non-compliance with these characteristics makes the pen drive unusable with our instruments.
The Fuel Computer (F.C.) is not an instrument of absolute precision.
While a F.C. is an excellent flight management assistant, it should never be treated as an absolute primary measuring device or a substitute for manual fuel planning and visual pre-flight checks. Systems based on volumetric transducers (inline turbines) are inherently analog devices subject to various physical and environmental variables.
Here is what happens behind the digital screen and why the readings can vary:
1. Fuel Density Changes with Temperature
The sensor installed in your fuel system is volumetric: it measures the volume of the fluid (how many liters/gallons pass through), not its mass (weight). However, fuel expands with heat and contracts with cold. At the exact same volume measured by the turbine, less energy (less fuel mass) is actually passing through in the summer compared to the winter. The instrument cannot automatically compensate for this change in density, which introduces a baseline margin of error.
2. Turbine Response is Non-Linear
The instrument's software calculates fuel flow based on the number of pulses generated by the spinning turbine. This response is not perfectly linear across the entire operating range:
At Low Flow Rates (e.g., taxiing or descent): Mechanical friction within the sensor can cause the turbine to spin slower than the actual flow, underestimating fuel burn.
At High Flow Rates (e.g., takeoff or climb): The fluid can experience "slippage" past the blades or cause sensor saturation, altering the pulse-to-liter ratio.
While the system is calibrated to be as accurate as possible within typical cruise flow rates, it will inherently be less precise during other phases of flight.
3. "Pulsing" and Microbubbles (Cavitation and Pulsations)
Flowmeters read anything that moves the turbine, but they cannot distinguish what is moving it:
Pulsating Flow: In carbureted engines, the alternating opening and closing of the float needle valve creates a "stuttering" flow and pressure waves inside the lines. These pulsations can cause the turbine to wobble or over-spin, leading the instrument to overestimate consumption.
Air/Vapor Presence: Micro-cavitation caused by electric fuel pumps or heat in the engine bay (vapor lock) creates microbubbles. The turbine will spin rapidly as these air pockets pass through, registering a high fuel burn rate that does not exist in reality (the engine is not burning that air).
4. Installation Tolerances
Accuracy depends heavily on where and how the sensor is installed. Proximity to hose bends, restrictions, pumps, or heat sources creates turbulence in the fluid, altering the turbine's behavior compared to ideal factory testing conditions.
For flight planning and safety reserves, your your fuel onboard must always be calculated based on traditional cross-country planning (flight time × known engine burn rate) and verified by a visual inspection before take off.
While a F.C. is an excellent flight management assistant, it should never be treated as an absolute primary measuring device or a substitute for manual fuel planning and visual pre-flight checks. Systems based on volumetric transducers (inline turbines) are inherently analog devices subject to various physical and environmental variables.
Here is what happens behind the digital screen and why the readings can vary:
1. Fuel Density Changes with Temperature
The sensor installed in your fuel system is volumetric: it measures the volume of the fluid (how many liters/gallons pass through), not its mass (weight). However, fuel expands with heat and contracts with cold. At the exact same volume measured by the turbine, less energy (less fuel mass) is actually passing through in the summer compared to the winter. The instrument cannot automatically compensate for this change in density, which introduces a baseline margin of error.
2. Turbine Response is Non-Linear
The instrument's software calculates fuel flow based on the number of pulses generated by the spinning turbine. This response is not perfectly linear across the entire operating range:
At Low Flow Rates (e.g., taxiing or descent): Mechanical friction within the sensor can cause the turbine to spin slower than the actual flow, underestimating fuel burn.
At High Flow Rates (e.g., takeoff or climb): The fluid can experience "slippage" past the blades or cause sensor saturation, altering the pulse-to-liter ratio.
While the system is calibrated to be as accurate as possible within typical cruise flow rates, it will inherently be less precise during other phases of flight.
3. "Pulsing" and Microbubbles (Cavitation and Pulsations)
Flowmeters read anything that moves the turbine, but they cannot distinguish what is moving it:
Pulsating Flow: In carbureted engines, the alternating opening and closing of the float needle valve creates a "stuttering" flow and pressure waves inside the lines. These pulsations can cause the turbine to wobble or over-spin, leading the instrument to overestimate consumption.
Air/Vapor Presence: Micro-cavitation caused by electric fuel pumps or heat in the engine bay (vapor lock) creates microbubbles. The turbine will spin rapidly as these air pockets pass through, registering a high fuel burn rate that does not exist in reality (the engine is not burning that air).
4. Installation Tolerances
Accuracy depends heavily on where and how the sensor is installed. Proximity to hose bends, restrictions, pumps, or heat sources creates turbulence in the fluid, altering the turbine's behavior compared to ideal factory testing conditions.
For flight planning and safety reserves, your your fuel onboard must always be calculated based on traditional cross-country planning (flight time × known engine burn rate) and verified by a visual inspection before take off.
When an FX75 servo disengages, a specific error message is always displayed on the connected instrument screen, providing a clear indication of the reason for the disengagement.
Deleting the error from the display without reading it and calling Flybox for help is not useful. If, however, the reason for the disconnection is specified immediately upon opening the support ticket, we will be able to direct the customer right from the first response.
Refer to the instrument manuals in the "Autopilot Alarm" section for detailed explanations on the reasons for each type of disengagement.
Deleting the error from the display without reading it and calling Flybox for help is not useful. If, however, the reason for the disconnection is specified immediately upon opening the support ticket, we will be able to direct the customer right from the first response.
Refer to the instrument manuals in the "Autopilot Alarm" section for detailed explanations on the reasons for each type of disengagement.
In case of inability to connect to Wi-Fi (the network is called: FLYBOX_WIFI_XXXXXXXX) check:
- make sure you have entered the correct password (it is written on the Wi-Fi stick)
- make sure the green LED is on (it flashes when data is being transmitted)
- make sure you are connected to the correct network
- make sure you have entered the correct password (it is written on the Wi-Fi stick)
- make sure the green LED is on (it flashes when data is being transmitted)
- make sure you are connected to the correct network
The first thing to check is whether the electronic MOSFET bridge output is operational.
If it does not move, it means that the output is burnt out and the Controller needs to be sent for repair.
If it does not move, it means that the output is burnt out and the Controller needs to be sent for repair.
Per ogni strumento Flybox tra quelli che possono visualizzare la Oil Pressure, serve verificare che il modello di sonda sia compreso tra quelle descritte sul relativo manuale.
Inoltre nel menu di settaggio dello strumento va confermata la sonda corretta.
Inoltre nel menu di settaggio dello strumento va confermata la sonda corretta.
If the current indication used by the Flybox sensor - Code 601060 is reversed, it will be sufficient to reverse the direction of the current flow by swapping the 2 large terminals A+ and A-.
The rotor RPMs are usually detected by inductive sensors, or Hall effect sensors.
When a rotor speed measuring instrument does not display the correct reading or does not display a reading at all, the first thing to do is to check that the signal level and polarity are compatible with the input of the instrument being used.
The Flybox sensor - Code 105896 (PNP output) works with our instruments with the addition of an external pull-down resistors.
Sensors other than the one we supply require an assessment of whether or not the resistance is suitable.
Read in the menu of the installed instrument how to set the number of pulses per revolution of the rotor.
When a rotor speed measuring instrument does not display the correct reading or does not display a reading at all, the first thing to do is to check that the signal level and polarity are compatible with the input of the instrument being used.
The Flybox sensor - Code 105896 (PNP output) works with our instruments with the addition of an external pull-down resistors.
Sensors other than the one we supply require an assessment of whether or not the resistance is suitable.
Read in the menu of the installed instrument how to set the number of pulses per revolution of the rotor.
There is no rule among sunglasses manufacturers that requires the polarizer to be oriented in a certain way.
At Flybox, we use all displays with the polarizer oriented horizontally, but sometimes it can happen that some glasses have the lenses oriented differently. The consequence is that in flight, the display becomes unreadable unless you rotate your head by 45 or 90 degrees.
For this reason, the American FAA advises against the use of polarized lenses in the cockpit. Here we provide the official text from the FAA:
"POLARIZATION. Polarized lenses are
not recommended for use in the aviation
environment. While useful for blocking reflected
light from horizontal surfaces such as water or
snow, polarization can reduce or eliminate the
visibility of instruments that incorporate anti-
glare filters".
If you are incorrect in this problem, now you know the reason, but the decision on how to solve it is up to you.
At Flybox, we use all displays with the polarizer oriented horizontally, but sometimes it can happen that some glasses have the lenses oriented differently. The consequence is that in flight, the display becomes unreadable unless you rotate your head by 45 or 90 degrees.
For this reason, the American FAA advises against the use of polarized lenses in the cockpit. Here we provide the official text from the FAA:
"POLARIZATION. Polarized lenses are
not recommended for use in the aviation
environment. While useful for blocking reflected
light from horizontal surfaces such as water or
snow, polarization can reduce or eliminate the
visibility of instruments that incorporate anti-
glare filters".
If you are incorrect in this problem, now you know the reason, but the decision on how to solve it is up to you.