EDM 350 System and How it works ?

EDM 350 The aircraft Engine Data Manager 350 (EDM 350), by J.P. Instruments is a small box-like device with an LCD screen on the front and it keeps track of the vital functions of the aircraft engine.

The faceplate requires just 3.25 square inches of space on your aircraft dashboard and is easily fitted.

Although physically small in size, this little gadget is packed with electronic chips that analyse 24 different engine functions in any 4-cylinder aircraft. The basic 4-cylinder EDM 350 kits start at just $798 while the 6-cylinder EDM 350 kits are priced at $988. Both representing enormous value for money.

Fitting the EDM 350 is as easy as can be – first, attach all the probes to the engine and thread them out of the empty space 3.25-inch space. Next, attach the probes and wires to the EDM 350 and ‘plug-in’ the EDM 350 Aircraft engine data manager into the empty socket. That it, you’re good to go.

How the EDM 350 works:

The EDM 350 is like a little on board computer. It has ‘high‘, ‘low’ and ‘normal’ figures for 24 different engine parameters pertaining to 2 ~ 4 cylinder aircraft engines. Once the aircraft engine is switched on, the 24 sensors attached to different parts of the aircraft engine, pickup data and transmit the same via wires to the EDM 350.

As the data begins to flow in, the EDM 350 begins to display the information on the LCD screen. The information may be displayed graphically or in actual numbers depending on how the pilot wishes to view the information.

So long as all parameters are in the ‘normal’ range it simply displays the data. If however, any parameter is in the ‘low’ or ‘high’ range, an audio-visual alarm is triggered. The ‘lows’ and ‘highs’ can be entered manually by the pilot.

With the EDM 350 on board, the pilot is free to fly the plane and enjoy the experience rather than having to concentrate constantly the status of the engine.

Here are the 24 different engine parameters that the EDM 350 keeps a watch over:

1. CHT – Cylinder head temp – probes and harness included.
2. EGT – Exhaust gas temp.
3. VDC – Voltage display.
4. ROP/LOP – Lean finder.
5. CLD – Shock cooling on all cylinders.
6. DIFF – Engine health.
7. Internal Memory – Enough memory to record 600 hours of data (recorded every 6 seconds).
8. USB Port – Convenient data port for quick and easy download of engine data.
9. EZTrends Software – Graphics software with Google Earth location included.
10. MAP – Engine Manifold pressure.
11. RPM – Prop rotation speed.
12. O.T. – Engine oil temp.
13. F.P. – Fuel pressure.
14. O.P. – Engine oil pressure.
15. OAT – Outside air temp.
16. CRB – Carburettor temp.
17. TIT – Turbine inlet temp.
18. CDT – Compressor discharge temp.
19. L-R-Main – Fuel quantity in all tanks.
20. AMP – Battery load output in amps.
21. V-2 – Second volts readout.
22. % HP – With FF, OAT and RPM.
23. Amp-2 – Second load readout in Amps.
24. FF – Fuel flow includes:
• GPH – Gallons per hour.
• REQ – Fuel required to way point / destination.
• USD – Fuel used.
• H:M – Endurance in hours and minutes.
• MPG – Miles per gallon


1.EGT probes must be mounted 2 to 4 inches from aircraft cylinder head.
2.If EGT clamps are too short, please buy larger clamps (available with J.P.I)
3.If EGT probes appear to be lose, please remove the probe, squeeze the thimble and reassemble.
4.Existing TIT probe cab be used only if the aircrafts TIT probe has the same type thermocouple.

For more information on EDM 350 Aircraft engine data manager by J.P. Instruments, please visit: https://www.jpinstruments.com/shop/edm-350/


Installation of CHT Bayonet Probe in Aircraft

CHT Bayonet Probe The CHT Bayonet probes are the threaded probes and are commonly known as ‘CHT Bayonet Probes’. These are typically used on Lycoming engines in aircraft.

Let us start with extending the CHT probes – most CHT probes available in the market feature cold-junction compensation. Cold-junction compensation means that the temperature of the cold junction of the thermocouple is measured (at the RDAC) and this temperature is used to compensate for ambient temperature with the small voltage readout between the two alloys at the thermocouple junction. For this reason, it is important that type-K extension wire be used for type-K thermocouples. You can use the same extension wire for EGT’s and CHTs. The length (within reason), is not critical and will have little or no effect in the temperature reading.

Installation of CHT Bayonet probe in aircraft is actually quite simple:

1. Begin by screwing in the threaded CHT probes into recesses in cylinders (3/8-24 – no washers are required)
2. Use Thermocouple Channels TC5 through TC8 if you have a 4-cyl engine and TC7 through TC12 if you have a 6-cyl engine.
3. Remember that some CHTs are type-J thermocouples (these can be used).
4. Remember that with type-K thermocouples that Yellow is Positive and Red is Negative.

There CHT Probes extension kits available in the market and most include the type-K thermocouple wire, splice barrels, and a length of inner heat shrink tubing. When heated, this heat shrink gets quite soft inside and this eliminates all air inside the splice and makes an airtight seal. If required you and use heat shrink and we recommend you use Raychem SCL-3/16 heat shrink.

Here’s how you extend the wires of CHT Bayonet probe in Aircraft Engine Data Management :

1. Use a wire stripper to strip the CHTs and make small loops with the ends.
2. Do the same with the type-K extension wire (if extension is required).
3. Prepare the splice barrels and heat shrink.
4. Place a splice barrel and short length of shrink wrap on the wires.
5. Lay the CHT and type-K extension loops over each other.
6. Slide the splice barrel over the parallel loops.
7. Crimp the splice barrel with a crimping tool (use a crimping tool with a grip for non-insulated terminals –the ones that have a cradle on one side and pierce a small hole on the other).
8. Slide the heat shrink over the splice and heat with a heat gun or lighter.
9. That is a solder-free, airtight and airless parallel thermocouple splice.

For ordering or more information, please visit: https://www.jpinstruments.com/shop/cht-bayonet-probe/

Standard Features & Specifications of EDM 800 System

EDM 800Features & Specifications of EDM 800 include:

• Easy front panel programming by the pilots
• 24 Pilot programmable alarm limits via front panel
• No more calculating – displays both leaned temperatures below peak and peak.
• Just 2 ¼” installation space required.
• LeanFind™ is a true peak detect technology that finds the first and last cylinder to peak
• Fuel flow data for single 6-cylinder engine.
• Built in alarm triggered by unusual battery voltage
• EGTs with up to 1°F resolution data
• EGT with DIF low to high alarm
• Pilot selectable index rate
• Every cylinder monitored by shock cooling
• Long term memory now stored in memory cards
• 30-hrs worth of flight data can now be stored on memory cards
• Easy engine analysis via memory card.
• EDM 800 is a FAA Approved as primary instrument for CHT, OIL, TIT, RPM, MAP, Fuel Flow
• Pilot selectable fuel rate display (pounds, gallons, kilograms or litres)
• Now incorporates a low fuel quantity alarm
• Now comes with optional GPS interface to interact with fuel flow rate and provides data on total amount of fuel consumed, total fuel remaining and time to empty at the current fuel flow rate.

Clearly, with so many features and specifications of the EDM 800 for aircraft, the pilot need no longer strain his eyesight and attention on a bunch of dials. Thanks to the programmable alarm, if anything is even slightly fishy, the audio-visual alarm will sound and bring the anomaly to the pilot’s attention.

The EDM 800 (especially the one manufactured by J.P. Instruments), uses the latest microprocessor technology to monitor up to 24-critical parameters of the aircraft engine and moreover, it does this four times a second.

Superior to it’s predecessors, the EDM 800 has a technologically updated fuel flow data monitor besides a host of other features. For example, leaning is automatically done using the patented LeanFind™ software. You also have more Aircraft Engine Monitor diagnostic information available. In fact, it records, all 29 functions, every 6 Seconds (24 of which, are pilot programmable), and its memory can hold up to 30-hours of engine data. The EDM 800 also features a unique ‘long-play’ mode i.e the instead of every 6 seconds, engine data is recorded once every minute thereby extending the capacity of the memory card to 550 hours of data. This data can be downloaded via the optional USB port.

The EDM 800 converts your RPM manifold pressure outside air temperature and fuel flow into horsepower. To achieve this a small one-time calibration is required. The details are in the instruction manual and easy to follow. To maximize engine performance, the EDM 800 also provides the pilot with a full-time in-flight readout of aircraft engine horsepower.

All of JPI’s EDM’s are TSO’d for Quality

For more information please visit: https://www.jpinstruments.com/shop/ed-800/

Aircraft Engine Monitor keeps your engine healthy, efficient and safe

EDM 350I once had this dream actually, a nightmare – I was flying my Cessna 152 over Florida Keys enjoying both the flight and the views when all of a sudden, I saw there were no engine monitors or gauges in the cockpit. My panic was so acute that I woke up with my heart pounding and then thanked my stars it was only a nightmare.

Those of us who are used to flying with data monitors, GPS and a handful of gauges, know how much we depend on them to know not just the health status of the aircraft but also our current geographic location, height etc.

I remember that in comic books as well as WWII films pilots would know something was wrong just by listening to the difference in engine sound. But any pilot will tell you that engine sound changes after something has happened which basically means the pilot has to enter into a fire-fighting mode and its all guess work from there based on how the aircraft is handling.

A newly qualified pilot wouldn’t know what the heck was happening – whether an engine was being starved of fuel or cylinders are over-heating, or whether the aircraft was about to suffer a catastrophic failure of some sort.

While experience counts and an experience pilot will probably make a reasonably good guesstimate as to where the problem is, it would still be a guess. But throw in a handful of gauges and the whole situation changes. Throw in an engine data monitor (EDM) and bingo, you know exactly where the problem is and more importantly, how acute it is and how to react to it.

With availability of aircraft engine data, blind panic gives way to determined calmness – as a pilot, you now know what exactly it is that is wrong and what to do to bring the aircraft safely down to earth – preferably in one piece.

An engine may belong to a truck or aircraft engine or a simple water pump. Every engine has a set of manufacture determined parameters within which it has to operate. Any deviation could lead to a catastrophic failure of the engine. On the ground you can simply switch off the engine but a pilot in the air, does not have that luxury.

Manufacturers such as J.P. Instruments of USA, not only make aircraft engine monitors and quality engine Aircraft Gauges, they also have also included artificial intelligence into the display units to warn the pilot(s); if any engine parameter is not in conformity of its safe operating limits. A potential problem therefore, comes to light much before it becomes serious. The aircraft engine monitor keeps your engine healthy, efficient and safe.

Also, these days the aircraft engine data monitors have built-in memory slots. At end of each trip you just pop out the memory card and hand it over to your mechanic who in turn will plug it into his diagnostic unit and generate a detailed analysis of the flight and aircraft engine performance. Any problem areas are instantly identified and passed on the repair crew. This way you also have a valuable history of the aircraft’s engine performance. The Aircraft Engine Monitor keeps your engine healthy, efficient and safe.

I hope my dream never becomes a reality either to me or to any other pilot. Fly safe, enjoy life.

Compressor Discharge Temperature (CDT) Probe – How it works in Aircraft?

CDT ProbesFor the uninitiated, the gas turbine you see in the single and twin-engine aircraft is an internal combustion engine that uses air to drive the engine and propeller, which in turn, propels the airplane. It achieves this with the help of heat energy from fuel that it converts to mechanical energy via the pistons.

Here’s how the gas turbine combines with the compressor:

1. Intake of air
2. Compression of the air
3. Air is mixed with right quantity of fuel and ignited.
4. Energy release in above process is used to drive the plane forward.

Now just as a car engine gets hot and needs to be kept cool, ditto the aircraft engine. In fact, keeping the aircraft engine cool is even more critical because result of a fire in the aircraft engine (caused due to ignition of fuel due to excessive heat), would be a crash and probable death of all occupants. A car on the other hand, can just be brought to a stop by the road side.

Compression always leads to heat. So, when air is compressed in an aircraft engine, heat is generated. Also, the mass flow rate of air through the engine will have an effect on engine temperature and engine performance. Other factors that affect aircraft engine performance include the engine operating temperatures, the pressure ratio of the compressor, turbine inlet temperature, and also the individual component efficiencies.

An optimum turbine inlet temperature, pressure ratio, and air mass flow rate are selected to obtain the required performance in the most efficient manner. For this reason, it is imperative that the compressor temperature be closely monitored and corrective action be initiated in the event of excessive compressor temperature.

The compressor supplies air at high static pressures typically 33 pounds of air per second. This causes a raise in the temperature of the air by about 550F as the air is compressed and moved rearward. Excess heat will lead to a drop in the aircraft engine performance. This is where the Compressor Discharge Temperature (CDT) probe comes into play.

JPI instruments manufacturers the World’s best quick responding CDT Probes which is installed just after the inter-cooler. The probe is installed with a #40 stainless steel clamp. A large clamp is supplied to fit around the airport leaving the inter-cooler.

Every CDT probe is provided with a stainless steel clamp Thimble, a Stainless Steel Exhaust Seal Washer, a Stainless Steel Screw Type Clamp and a 10 Ft. Option Wire. The CDT probe is either connected to an EDM in the cockpit or to a standalone temperature gauge.

For more information on CDT probes manufactured by JPI, please visit: https://www.jpinstruments.com/shop/cdt-probe/

Slim-line Gauges – Their Usefulness in Aircraft

Slim-line GaugesA single or twin-engine aircraft cockpit jampacked with gauges of different types and sizes might look awesome or look like a spaceship to passenger or friend you are trying to impress but for the pilot – they are a pain to keep track of during a flight. The pilot can’t possibly be keeping track of all the gauges and also fly the plane at the same time.

True, each gauge provides vital information on a particular part of the aircraft engine. This reminds us of wrist watch – most of them even today, display just the time. Newer models display time and date – maybe even the day of the week. Still newer models incorporated a chronograph, a stop watch and even have an alarm. The latest are the “digital smart watch” that can even display your heart rate and how many step you walked during the day. As technology improved so did the number of features on the once humble wrist watch?

Ditto the gauges in the aircraft cockpit. Earlier they used to be analog only. Today, digital versions are available. As an aircraft owner, you can either choose to replace a single old analog gauge with a slim-line digital version of it or, you can replace a whole bunch of analog dials and gauges with a single slim-line digital gauge.

What’s with the “slim-line?”

Well, “slim-line” means it occupies very little physical space so everything of importance can be placed right in front of the pilot instead of being spread all over the cockpit.

Another major difference is that modern slim-line gauges are ‘digital’ meaning, they display the data in numbers or graphs or numbers and graphs instead of a needle on a dial. Numbers make it more accurate. So instead of (say) displaying three-quarters on a dial for fuel in the tank, you can now see the exact quantity in litres or Gallons.

Naturally, the connection between the slim line gauge and the aircraft engine will also change. The new replacement will be a sensor and wires connecting the sensor with the Slim Line Gauges. The wires transmit data in electrical pulses that could be interpreted by the smart electronics circuits inside the slimline gauges.

More advancement:

Of course, you could go the whole nine yards and install an Engine Data Manager (EDM) which in turn is about the size of an iPad and replaces a whole range of gauges. So, instead of having several gauges – slim-line or analog, you have just one EDM.

The EDM did not just replace analog gauges, it also replaced slim-line gauges by displaying several sets of data in a single window. The EDM is capable of displaying data for fuel, Oil temperature, OAT, RPM, Voltage, Manifold Pressure, OIL Pressure and so forth.

In fact, not only does it display the information, it can also be programmed to trigger an alarm for abnormal readings e.g. low fuel level, abnormal oil temperature, abnormal pressures etc.

In most cases, single and twin-engine aircraft owners who had analog gauges, usually replaced them with slim-line gauges and later on, upgraded to EDM’s. Some who had the budget, went directly from analog gauge to EDM. How you proceed depends entirely on your budget.

The difference between slim line and EDM is that each slimline gauge usually displayed one piece of information. So, you had a slimline gauge for OAT, RPM, Oil temperature, Voltage, Manifold Pressure, OIL Pressure and so forth.

For options on modern slim line gauges, please visit: https://www.jpinstruments.com/shop/slim-line-experimentalhomebuilt/

Installation of J.P.I. Fuel Scan 450 for Aircraft

Fuel Scan 450This document assumes your general familiarity and knowledge of aircraft engines and its systems. If you are not familiar with it, please seek the services of an authorised aircraft maintenance engineer.

Installation of the JPI manufactured Fuel Scan 450 in cockpit panel:

Locate / create a 2.25 or 3.125 diameter hole in the instrument panel, where you would like to mount the indicator. The instrument configures itself automatically for 14 or 28 volt aircraft systems. The depth required for the instrument is 1.5 inches (less connectors) and is 2.6 or 3.5 square behind the panel.

Wiring from sensors to the cockpit:

The fuel flow wires from the probes of the Fuel Scan 450 must be routed through the firewall using flame retarding silicone and fireproof rubber grommets. Using existing hole will make your task much easier. Ensure the wires are routed away from any high temperature areas (i.e. turbochargers, exhaust stacks etc.).

Secure the Fuel Scan 450 probe leads to a convenient location on the engine, allowing for sufficient slack to absorb engine torque. Please ensure the fuel flow transducer wires do not touch any metal parts of the air-frame or engine since abrasion during flight will destroy this wire. Refer to the manual for the wire connection.

Mounting the Fuel Flow Transducer of the Fuel Scan 450:

Before you start, know that if your aircraft engine is equipped with a fuel return line from the carburettor back to the fuel tank, then you have to use two transducers. The transducer output port should be mounted at same height or ideally, lower than the carburettor inlet port (or fuel servo on a fuel injected engine). In some aircraft, due to space constraints, this might not be possible in which case, please use a loop placed in the fuel line between the Fuel Flow Transducer and the carburettor or fuel. As far as possible, do not hard mount the transducer to the carburettor or fuel servo.

Also, do not remove the caps on the flow transducer until the fuel hoses are ready to be installed. Carefully note the fuel flow direction marked on the transducer – it is important that the fuel must flow in that direction only.

As you fit the flow transducer for the Fuel Scan 450, mount it so the wires exiting the transducer are pointing upwards.

Examine the fuel hose pipes and remove any loose material or dirt that might be deposited. Next, connect the fuel hose pipes. If using air pressure to clean the hose, ensure it does not enter the Fuel Flow Transducer.

More information on Fuel Scan 450 can be obtained here: https://www.jpinstruments.com/shop/fuel-scan-450/