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Digital Gauges edmmonitors:   Followers: 11 ; Following: 13

Optimization and Characterization of EDM 790 System

EDM 790The best EDM that money can buy in under ten thousand dollars (U.S) for 4 or 6-cylinder aircraft engine with transducers and all? The answer has to be EDM 790 manufactured by J.P. Instruments, U.S.A.

It’s not just an advert claim, the Engine Data Management 790 system is truly the most advanced twin piston engine-monitoring instrument on the market. The EDM 790 has been TSO’s for quality and is rightly thought of as a Flight Engineer and Maintenance Manager that has your back covered.

Covers to 29 critical parameters

Armed with the latest microprocessor technology, the EDM 790 will monitor up to 29 critical parameters of your aircraft engine – 4 times a second! It boasts of a linearized thermocouple accuracy of better than 0.1 percent or 2 F° and this boast has been tested and verified by the FAA.

It never sleeps

Constantly on the alert, the EDM 790 will keep an eye for you on 29 critical parameters that are automatically checked four times every second. No matter which screen you might be currently looking at, the EDM 790 will keep running checks on all 29 parameters in the background.


The EDM 790’s accuracy stems from its linearized thermocouples. There is nothing in the aviation market that compares to J.P.I’s linearized accuracy.


Two buttons on the faceplate is all that it takes to programme the EDM 790 or to access all its functions. Leaning is accomplished automatically using the Lean Find procedure. With the EDM 790 it is now possible to have substantially more diagnostic information available for your maintenance crew.

The Advantage of EDM 790

1. Computer Assisted Diagnostics covering the entire aircraft system from the cockpit. On detecting any error, the specific code is displayed.
2. Easy-to-use 2-button programming.
3. Twenty-nine parameters checked 4 times a second and this includes the EGT Differential, Alternator Voltage, Fuel Flow Instruments and Shock Cooling.
4. Displays variable Scaling of EGT Bar Graph.
5. Its amazing Lean Find Mode identifies the first and last cylinder to peak while the Peak Find with quick responding probes, automatically captures the EGT Probes or TIT peak value.
6. USB Download Box Port for downloading of data.
7. The EDM 790 is the only FAA approved graphic engine monitor with a complete fuel flow system.
8. Temperature detection accuracy is ONE degree (even for EGT).
9. Paired with JPI’s “grounded” fast response probes.
10. Cooling rate and shock cooling checked on each and every cylinder.
11. EDM 790 features a “Normalize Mode” for accurate trend monitoring. Bars are in 10o increments.
12. Alphanumeric scanning display of 29 functions or channels.
13. TSO’s for Quality and Reliability with FAA, STC approved Fuel Flow .
14. Three-year warranty.

For more information, please visit:

Post by Digital Gauges (2018-08-14 02:29)

Tags: EDM 790 EGT Gauges

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How Slim-line Tach Gauges Works in Aircraft?

Slim-line Tach GaugesThere was a time when portable watches used to be two inches in diameter and as much as three-quarters of an inch thick. These watches were kept in the pocket and taken out only when you needed to know the time.

We all know how these pocket watches evolved, became slimmer and turned into wrist watches. The display gauges in the aircraft cockpit underwent a near identical transformation except that; on the evolution time-scale, they evolved nearer the electronic revolution so instead of becoming slimmer versions of their earlier self, they turned into slim line digital gauges.

Naturally, the sensor that actually picked up the aircraft engine data also got transformed and began transmitting data in electrical pulses that could be interpreted by the smart electronics circuits inside the slimline gauges.

In next to no time the integrated circuits got so miniaturized that an entire circuit was fitted inside a single chip 2 x 1 cm in size which came to be called the IC chip (short for integrated circuit). During this same period, onboard memory was developed which totally transformed the way data was handled and interpreted because data could now be temporarily stored, recalled and used – almost in the same way as your calculator memory.

Next came a permanent memory module – the Random Access Memory (RAM). Thanks to this new development, instead of data being lost when the aircraft engines were turned off, critical engine data could be stored and retrieved on a semi-permanent basis.

Along with the miniaturization of the innards of the slimline gauges in aircraft, the front end i.e. the display itself underwent a change and the humble analog dial was replaced with a Liquid Crystal Display (LCD). So now the pilot could see the actual digits. This was also the time the analog wrist watch began to get replaced with a digital wrist watch. This was also the time when electronic pagers began to make their appearances in the market.

The next big development occurred when the memory modules was linked to the faceplate of the Slimline Pressure Gauge which totally revolutionized and enhanced the value and usefulness of the slimline gauge. The pilot could now directly interact with the gauge by feeding in alarm triggers in the form of upper and lower limits. For example, minimum temperature and maximum temperature. These figures would be stored in the memory module and constantly compared with the incoming temperature data.

So, if the temperature fell below the minimum figure or rose above the maximum figure, an audio-visual alarm could be triggered. This meant the pilot(s) no longer needed to keep monitoring the gauges and instead, could actually enjoy the flight.

Each slimline gauge usually displayed one piece of information. So, you had a slimline gauge for Oil Temp, OAT, RPM, Voltage, Manifold Pressure Sensor, OIL Pressure and so forth.

As of today, individual sensors pick up the data directly from the engine and transmit it as a voltage via wires to the individual slim line gauge for which it is meant. The electronic board and IC circuit onboard the slim line gauge interprets the incoming voltage, converts it into a meaningful number and displays it on the screen. The display was bright enough to be seen even with the sun directly behind the pilot.

For options on modern slim line gauges, please visit:

Post by Digital Gauges (2018-08-06 02:37)

Tags: Slim-line Tach Gauges RPM Sensor

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Working Principles of RPM Sensors in Aircraft

RPM SensorsFor this article, we’ve selected to explain the working principles of the RPM standard sensor for the pressurized Bendix series (manufactured by Teledyne Continental Motors):

The RPM sensor is connected to the magneto. To understand the sensor let us first begin with the “why” of things i.e. why is the magneto required in the first place is:

A magneto is required to power the sparkplug. Every combustion engine (including those used in aircraft), have sparkplugs. These provide the ignition or fire required to ignite the fuel-air mixture in the combustion chamber. The sparkplug purpose and functioning are identical to the gas lighters that your mom used to have; but are now built into the gas range in your home.

To work properly, the sparkplugs in turn require an awful lot of electrical volts to create the spark. And this electrical power needs to be very precise and delivered at the right moment.

A battery would not do the job efficiently so a custom-built power generator called the “magneto” was invented.

As the output power from the magneto needed to be precise, it therefore needed to function with precision. A malfunctioning magneto will mean that everything downstream will also malfunction. So, the pilot(s) need to know the instant the magneto isn’t working as intended.

Enter the RPM sensor. To understand the working principle of the RPM sensor, it is important to know a bit about the magneto itself.

The Magneto is basically a dynamo with a rotating magnet, a built-in breaker switch, a transformer and a distribution system to channel the power to the spark plugs. For reasons mentioned above, it is important that the magnet rotates at a speed that is within the prescribed range otherwise your spark plugs (and hence the engine) will misfire. To ensure that is so, you need the aircraft RPM Sensor. The RPM standard Sensor plugs directly into the magneto and transmits data to your EDM/ RPM gauge in the cockpit.

The Aircraft Level Sensors you use will depend on the magneto brand and model inserted in your aircraft.

If you need to install a new RPM sensor, make sure:

• The new RPM sensor is precisely aligned with the correct vent plug of the magneto. Here’s how you do it: peep into the magneto hole and you should see the rotating magnet in this hole. If you see anything other than the rotating magnet e.g. the ‘gear’, then you’re on the wrong vent.

• When everything is connected and the engines fired up, the Digital Gauges in the cockpit should read 2400 rpm for a 6-cylinder engine or 1800 rpm for 8-cylinder or 1600 for a 9-cylinder engine.

If you have a 4-cylinder engine with a dual mag, the rpm should be 1800 and for a 6-cylinder engine with dual mag, it should be 2400.

• The red wire to the RPM standard sensors should be supplying 5v+.

More information on JPI manufactured RPM standard sensors here:

Post by Digital Gauges (2018-07-19 03:20)

Tags: RPM Sensor RPM Gauges

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What is Manifold Pressure Sensor in Aircraft?

Manifold Pressure SensorAlthough it’s technically termed as aircraft manifold pressure monitoring, the word “pressure” in this case, is a bit of a misnomer. This is because the aircraft manifold pressure data is not about pressure but suction.

The cylinders in any aircraft engine are like a large suction pump because the cylinders are constantly sucking air into itself. The MAP sensor therefore, if anything, is reading suction not ram air pressure. So at idle power your MAP gauge might display between 10 and 12 inches when actual pressure outside is 30 inches. This means your engines are actually starving for air creating a vacuum pressure within the intake manifold.

As the piston descends with the inlet valve open, a partial vacuum is created. It is this vacuum sucks in fuel into the intake. Therefore, greater the vacuum, greater the air-fuel mixture and hence greater the power output from the aircraft engine.

So, the more air-fuel mixture pumped into the cylinders, the more power the engine develops and enables us to fly higher or faster. Now, if we measure air pressure in the induction system, just before it enters the aircraft cylinders, we will have a good idea of how much power we can develop.

In any normally aspirated aircraft engine (non turbo-charged), the manifold pressure gauge usually has a range of 10 to 40 in. hg. In a turbocharged engine, the limits as per manufacturer settings. Effectively, when the engine is shut down, the MAP should read roughly the same as current atmospheric pressure setting.

Generally, MAP Sensors are used in fuel injected Aircraft Gauges. These days, the manifold absolute pressure sensor provides instant manifold pressure data (as described above) to the engine's electronic control unit (ECU).

The data presented by the MAP is used to figure out the density of the air and calculate the engine's air mass flow rate. These figures in turn help the pilot determine the required fuel mix for the most optimum (or economical) combustion. This helps work out the ignition timing.

Alternatively, fuel-injected engine can also use the mass airflow sensor (MAF sensor) to detect the intake airflow. In most naturally aspirated engines, there is either of the above two. In forced induction engine however, both tend to be deployed. Usually the MAF sensor is parked on the intake tract pre-turbo while the Manifold Pressure Sensor is installed on the charge pipe leading to the throttle body.

A lesser known fact is that the aircraft’s MAP sensor data can easily be converted to air mass data using the speed-density method. For this, the air temperature and engine speed in Aircraft Engine Sensors are used.

Typically, modern EDM’s use MAP sensor data for on-board diagnostics (EBD), to test the functionality of the exhaust gas recirculation (EGR) valve.

Post by Digital Gauges (2018-05-24 02:21)

Tags: Manifold Pressure Sensor RPM Sensor

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What is a Fuel Flow Transducer in Aircraft?

Fuel Flow TransducerFuel flow transducers came to be used in aircraft around the early 70s. Vibration of an aircraft engine. It also had to meet the important FAA regulation regarding blocked rotor pressure drop which could not be more than 1.5 times the spinning rotor pressure drop. Fuel flows can be measured via a conventional rotor-based fuel measurement system or, via the more modern fuel flow transducer - a digital-technology based system. The advantage of this new technology fuel flow measurement system is that, it is impervious to pressures and therefore the data is more accurate.

The fuel flow transducer works upon a vane RPM Sensor that is usually located behind the fuel filter and works in combination with the manifold air pressure (MAP). The fuel flow transducer produces a current-pulse signal from an opto-electronic pickup that's fitted with a preamp. The signal amplification enables it to measure fuel flow that is as low as 0.3 gal/hour and this makes it more accurate than the conventional fuel flow measuring systems.

Here's how the Fuel Flow Transducer works: The fuel enters the flow chamber within the fuel flow transducer and begins moving along a helical path. This is to vent out any vapour bubble that might be present in the fuel and result in wrong reading. The rotational velocity of the liquid is directly proportional to flow rate. A neutrally buoyant rotor spins with the liquid between V-jewel bearings. Rotor movement is sensed when notches in the rotor interrupt an infrared light beam between an LED and phototransistor. Generally, the fuel flow transducer operates on 12 to 15V consuming just 30 to 50 mA. The red wire is +V power, black is ground and the white wire is signal. Although it contains digital technology, the Fuel Flow Transducer can operate at temperatures between -55°C to 70°C.

If you have a IO-540 300 HP engine with electric and engine driven pumps, the fuel flow transducer should be placed downstream of the engine pump and before the servo. Also, if you have a Rotax 100 ULS (dual carbs), the fuel flow transducer needs to be plumbed in just before the fuel pump – you do not need a second fuel flow transducer. When using a fuel scanner, please use only recommended fuel flow transducers – these are listed in the fuel scanner manual. For e.g. if your fuel scanner is manufactured by JPI use only JPI fuel flow transducers. Although fuel flow transducers work the same, there are minor internal variations and these will match the fuel scanners they are supposed to be paired with. So, using fuel flow transducer from a different manufacturer can result in erroneous Aircraft Fuel Flow Monitors reading.

The best fuel flow transducers are manufactured by JP Instruments more information here:

Post by Digital Gauges (2018-05-15 03:10)

Tags: Fuel Flow Transducer Fuel Flow Instruments

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What are the functions of Induction Air Temperature (IAT) probe?

Induction Air Temperature ProbeWe all know that every combustion engine (except maybe in rockets), rely on an external air source for combustion. Problem for aircraft is that, the air entering the combustion chamber may not always have the ideal temperature for a healthy combustion.

Cold air usually found at high altitudes for example, is denser than air at sea level. Cold air being denser, requires more fuel otherwise an air-fuel ratio imbalance occurs and the combustion will be erratic. If the combustion in an aircraft engine is erratic, and you know what will happen. So, when the air is colder than optimum temperature, there are two things you can do – either warm the air or squirt more fuel. Obviously, the latter is not an ideal solution because the aircraft can only carry as much fuel as the tanks will hold.

But before you can do anything, you need to know what the air temp is and that is where the induction air temperature or IAT probe in aircraft comes in. The function of the modern induction air temp therefore, is to sense and digitize the temperature of the air that is to flow into the combustion chamber.

Modern day aircraft have an onboard computer that automatically balances the air-to-fuel ratio. The IAT probe (apart from sending data to the Aircraft Engine Monitors) provides air temp data to the onboard engine computer that controls the aircraft engine. The onboard computer in turn, dynamically alters the air-to-fuel ratio by changing the timing of the injector pulses.

The Intake Air Temperature (IAT) probe is mounted in the air intake manifold of the aircraft. The tip of the IAT probe is exposed to external air entering the aircraft engine. Essentially, the IAT probe is a thermistor, so its electrical resistance changes in response to changes in the temperature of the sensor. This means that the return voltage from the IAT probe changes in proportion to changes in air temperature.

If the aircraft is experiencing combustion related issues, chances are, the IAT probe might be malfunction and that can happen if it gets coated with oil, sooth, feathers, dust and so forth. Loose or corroded wiring or connectors can also have the same effect. If the IAT probe transmits inaccurate voltage, the onboard Electronic Data Management Systems will miscalculate the air-to-fuel mixture and this could result in a rich or lean fuel mixture.

The resistance and voltage test specifications for your aircraft’s IAT probe can be found in your aircraft service manual and the leaflet that came with the IAT probe (if you’ve purchased a new one).

Once every few weeks, it would be a good practice to test your aircraft’s IAT probe and also check area around the probe to ensure it is free of oil and anything else that might contribute to inaccurate temp feedback.

Post by Digital Gauges (2018-05-07 02:11)

Tags: IAT Probe EDM Monitors

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Engine Data Monitor 730 System vs EDM 830

EDM 730 EDM 830This article provides you with relevant information to compare EDM 730 and EDM 830 aircraft engine data monitoring systems manufactured by J.P. Instruments.

EDM 730
From $1,557.00 to $3,965.00)

1. Colourful Graphics
2. Larger data display for easy reading.
3. Parameters in full colour
4. Annunciation of exceedances.
5. Less page swapping, more data per page.
6. FAA STC/TSO approved.

Package Form Factor:
1. Easy 3-1/8" mounting at the front.
2. Face is offset from centre to better fit in spaces where other equipment is currently located.
3. Four mounting options to satisfy tough mounting scenarios.
4. Just 2.5 inch depth
5. Easy upgrade with the JPI EDM-700/800 harnesses.
6. USB port for easy data downloads and software upgrades.
7. Programmable engine parameters.
8. Percent Horsepower display.
9. Press button Rich of peak or lean of peak operation.
10. Full graphical depiction of RPM and manifold pressure.
11. Full function Fuel Flow indicators computer system.
12. GPS option for enhanced fuel management.
13. Full EDM scanner functionality.
14. Unit easily set to display in either portrait or landscape mode
15. Monitors: 4/6/7/8/9-cylinder engines,
16. Turbocharged engines

1. JPI RPM Sensor Option 10-01720
2. JPI Oil Pressure Option 10-04075
3. JPI Manifold Pressure 10-04512
4. JPI TIT Option 10-27090
5. JPI OAT Option 10-27095
6. JPI Oil Temp Option 10-27100
7. JPI Carb Temp Option 10-27103

More information here:

EDM 830
From $2,575.00 to $3,550.00)

1. The JPI EDM 830 comes with wire harness with 6 foot leads.
2. The EDM 830 does come with fuel flow transducer.
3. TIT Probes option can be added (part # 10-27090).
4. The JPI EDM 830 is EGT, CHT Probes, Oil pressure and temperature, MAP, OAT, RPM and %HP.
5. JPI EDM 830 (and 730) are TSO'd for a secondary engine monitor.
6. Carb temperature probe is not included with the EDM-830 but can be purchased separately.
7. Display brightness can be adjusted.
8. OAT is included with the JPI EDM 830.
9. The EDM 830 comes with the EGT and CHT probes for 4-cylinder selection.
10. The EDM 830 is a secondary engine monitor and cannot be used as a replacement for primary gauges. Please maintain primaries.
11. P-Mag ignitions will require optional RPM interface cable part # 790969.
12. There is an angle mount available (part # 700830).
13. JPI EDM 830 is FAA approved for use in certificated aircraft.
14. The EDM 830 is a separate system and must use its own sensors. You must keep all original gauges and sensors.

4. JPI EDM 4CYL HARNESS 10-04661
5. JPI EDM 6CYL HARNESS 10-04663

More information here:

Post by Digital Gauges (2018-04-27 02:53)

Tags: EDM 730 EDM 830 RPM Sensor

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What are the Features and Specification of EDM 830 System?

EDM 830If you are looking to upgrade your cockpit with a new EDM look no further than the EDM 830 manufactured by World leader in EDM’s – J.P. Instruments.

For the next couple of years at least, the EDM 830 is going to rule the pack because the EDM 830 through its brilliant full-colour graphical LCD display totally revolutionizes the way aircraft engines are monitored.

Despite its small size (probably the smallest aircraft EDM in the market), it easily packs more features, functionality, and information in its onto its LCD screen than any other currently available aircraft EDM on the market. The latest feature addition is the Oil pressure gauge.

Being small in size is not the only reason that the EDM 830 can be easily mounted – the 830 incorporates a standard 3-4/8" format that can be mounted vertically (portrait) or horizontally (landscape) orientation. Behind the panel, the EDM 830 only requires 2-1/2". Connect the power supply, correctly plug-in the various cables from the aircraft sensors and you’re done – the EDM 830 is ready to fly when you are. And of course, the EDM 830 is FAA STC/TSO approved and comes with a 3-year warranty.

Here’s a short list of the main features and functions of the EDM 830:

1. RPM and manifold pressure with full graphical depiction. - Display includes: RPM, MP, %HP, IAT Probes, CDT, OAT, CAT, OIL

2. Pilot programmable engine parameters. - P, OIL T, CHT, EGT, VOLTS, EGT, DIF, CLD, F FLOW, F USED, F REQD, F ENDUR and F REM

3. Percent Horsepower display.

4. Lean of peak or Rich of peak operation at the touch of a button. - EGT 4 or 6 Probes, CHT 4 or 6 Probes

5. Full featured fuel flow computer system. - Volts, Shock Cooling

6. GPS enhanced fuel management. - LOP/ROP JPI Exclusive Leaning Mode

7. Full EDM scanner functionality. - Fuel Flow (USED, Remaining, GPH Endurance, GPS Destination)

8. When fitting, EDM can be oriented as per pilot convenience and display will auto-configure. - MAP, Oil Temperature, Oil Pressure, OAT

9. EDM 830 can be used in 4, 6, 7, 8 or 9 cylinder engines and Turbocharged engines. - The % HP (Requires OAT, RPM, MAP, & FF). The EDM 830 comes with Power Connector and all required harnesses. EZ Trends software is included. Data recording - 100 hrs Downloadable via USB Download Box port.

Optional functions of the EDM 830 include: CDT, IAT, CARB Temperature and TIT

Accessories available include: Single series fuel flow (with or without) transducer, fuel flow harness (10-04650). These are available for 4 and 6 cylinders aircraft engines too. Also available are the EDM TIT probe with shield and extension wire as also the EDM Oil Temp Probes.

Little wonder then, the EDM 830 manufactured by J.P. Instruments is amongst the best aircraft EDM’s on the market today. More information here:

Post by Digital Gauges (2018-04-19 02:28)

Tags: EDM 830 TIT Probes RPM Sensor

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Key Features of RPM Standard Sensor in Aircraft

RPM Standard SensorBased on the model of the magneto installed in your aircraft, there are several different models / types of RPM standard sensors for aircraft. The RPM standard sensors you select and use would therefore depend on the brand of magneto in your aircraft.

Typical RPM standard sensors (as manufactured by J P Instruments) include:

RPM Standard Sensor for pressurized BENDIX 1200 SERIES (JPI part # 10-05459)
RPM Standard Sensor for pressurized BENDIX 20 SERIES (JPI part # 10-05460)
RPM Standard Sensor for pressurized BENDIX DUAL MAG SERIES (JPI part # 10-05461)
RPM Standard Sensor for VENT PLUG SENSOR for BENDIX (JPI part # 10-05651) and,
RPM Standard Sensor for VENT PLUG SENSOR for SLICK (JPI part # 10-05652).

From the year 2002 onwards, IO-550 magnetos usually have a compatible RPM sensor installed (running on 5v), but you can opt for the better-quality RPM standard sensor manufactured by JPI.

Since we can’t write on each and every one of the RPM standard sensors, let us concentrate on the more popular RPM standard sensor for the pressurized Bendix series (manufactured by Teledyne Continental Motors).

Being simple in construct, the Bendix Magneto RPM standard sensors is easily maintained and therefore quite cost effective. Also, the Bendix Magneto RPM standard sensors manufactured by J.P. Instruments is highly accurate.

If you have just acquired an aircraft of your own and are not sure of the importance of the Aircraft Engine Monitors – here’s what it does:

The aircraft has sparkplugs and these require high voltage power. Rather than rely on the aircraft battery, the power to the spark plugs comes from a mini power generator called the ‘Magneto‘ - of which, there are different brands; the Bendix brand being more popular. The Bendix Magneto is a small power generator that has a built-in breaker switch, a transformer and a distribution system to channel the power to the spark plugs.

This power generator has a rotating magnet inside and it is important that it rotates at a speed that is within the prescribed range otherwise your spark plugs (and hence the engine) will misfire. To ensure all is well, you need the aircraft RPM Sensor. The RPM standard Sensor plugs directly into the magneto and transmits data to your Aircraft Engine Data Management in the cockpit.

It is important to have a good quality RPM standard sensor as it helps identify / eliminate the magneto as the source of engine problem.

When fitting your new RPM standard sensor, make sure:

• The RPM Sensor is aligned with the correct vent plug of the magneto (if you peep through, you should see the rotating magnet in this hole. If you see a ‘gear’ you’re on the wrong vent).

• A 4 cylinder engine should read 3600 rpm, a 6 cylinder engine should read 2400 rpm, a 8 cylinder should read 1800 rpm while a 9 cylinder engine should have an rpm of 1600. A 4 cylinder dual mag engine should have rpm of 1800 and a 6 cylinder dual mag should have rpm of 2400.

• The red wire to the RPM standard sensors should be supplying 5v+.

More information on JPI manufactured RPM standard sensors here:

Post by Digital Gauges (2018-04-11 02:44)

Tags: RPM Sensor Aircraft Sensors

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How to Install Fuel Flow Transducer 201B in Aircraft?

Fuel Flow Transducer 201BThis question comes up often enough so we decided to write on how best to install the fuel flow transducer model 201B manufactured by J.P. Instruments in an aircraft.

Orientation of the 201B fuel flow transducer:

To start off and assuming you have removed the existing fuel flow transducer, hold up the new 201B fuel flow transducer in a horizontal position with the three wires up – because this is exactly how it is to be fitted. Fitting the fuel flow transducer any other way will lead to its failure. When the fuel flow transducer is in the horizontal position, the rotor within it are proper oriented and aligned with fuel flow. This is how it is meant to operate. Also, while fitting it, be sure that there is no bend closer than 6 inches either in the inlet or outlet pipe i.e. no bends before or after the transducer. Also, do not use aluminium or brass fittings when installing the 201B fuel flow transducer – use only AN816-7 Steel. The transducer is engineered to seal tight so do not use Teflon tape, or other thread sealant compound of any kind. Also, the transducer is marked IN and OUT for the fuel lines – so make sure you attach it correctly or the rotor will malfunction. The maximum torque should not exceed 15 ft lb (180 lbs.) or roughly, two full turns past hand tight.

Installation location:

If your aircraft has a carburettor, the fuel flow transducer should ideally be at the same height as the carburettor. If it is higher, fit an anti-siphon loop in the line that peaks higher than the transducer. If your aircraft sports a fuel injected engine, fit the fuel flow transducer between the engine fuel pump and the servo regulator. If your aircraft has that unique vapor return line, install the fuel flow transducer between the servo regulator and the flow divider (spider).

We have seen aircraft with Aircraft Level Sensors mounted between the electric boost pump and the mechanical pump – this is not recommended. Also, please do not hard mount the transducer to the engine as engine vibration can damage the internal rotor or cause it to malfunction and give misleading results. When installing the 201B fuel flow transducer, the wires are to be connected to the EDM. The fuel flow transducer gets its power supply (12V) directly from the EDM. Also, the wires should not be route along with or adjacent to ignition wires, alternator wires, spark plug leads, or cabin heater ignition wires.

When done, set the K-factor. The Fuel Flow Transducer 201B will have a K-factor of ~29.


It might be worthwhile to also procure a Fuel Flow Tester (just $35.00) for testing instrument and transducer.

Fault finding:

Some pilots called in to report consistently high Fuel Flow indicators readings. If you have followed above installation procedure correctly, check for air entering system at selector valve (may require a change of the O-ring). Here’s a test: The next time the aircraft is flown in cruise, turn on the boost pump for one minute. If the fuel flow drops, then this is an indication that air is leaking into the fuel line upstream of the transducer. It is possible that air is leaking into the system through the seal valve or other connection. Fuel stain may not be visible.

Post by Digital Gauges (2018-04-04 03:30)

Tags: Fuel Flow Transducer Fuel Flow Transducer 201B

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