Record Mode:

The EDM-700 Data recording model automatically records as many as 36 engine temperatures and 4 pressures, recording one set of readings every second, hour or however you program its preferences. All engine data is "time stamped" with total engine starts, Hobbs time, day, month, year and time of day, and are permanently stored within the CPU module.

Instead of carrying your home computer to your airplane to retrieve data, a credit card size memory device (Data card) is inserted into a slot in the CPU module and instantly, 100 hours of flight data are copied. The original data stored in the CPU is not destroyed during this process. Once the data report is printed out, you have a printed log to dispute any engine warranties that could arise. This data card format allows for time, day, month, year and time tracking plane usage, by giving each pilot a data card and using it to retrieve data and get an instant printout of the flight parameters. JPI probably has more engine data, on different aircraft engines than the major manufacturers have themselves. Our experienced technicians know what to look for when reviewing engine data. As a service to our customers, JPI can copy your engine data onto floppy disk, in a spreadsheet format for viewing on a PC compatible computer. Also available from JPI, a unique diagnostic software package for diagnosing your own engine data if that is what you prefer. World renowned pilot and aircraft designer, Dick Rutan chose the EDM for his Pond Racer Project, after having researched many EGT manufacturing companies. When referring to this engineering feet of a project, Dick said "We could not have done it without the EDM." One of Alaska's largest air cargo companies has logged over 800 recorded hours on their fleet of DC-6's.

Snapshot Mode:

Press the snapshot button to instantly record all diagnostic data when you suspect an engine abnormality. Imagine being able to show your maintenance department the proof of an intermittent problem occurring in flight. Now, that's high tech!

Alarm Mode:

Exceedence conditions are always recorded. The EDM-700 is shipped with conservative generic preprogrammed factory alarm limits. The alarm limits can be fine tuned by the owner, but any changes in limits are instantly recorded to show the new limits on the next print out. Limits can not be changed without the owner knowing. All probes are also checked 3 times per second for actual alarm conditions. False alarms are minimized by the self diagnostic routine in the EDM system. The probes (sensors), are compared to real engine conditions and are removed from the display if they fall out of the real alarm boundary. Should any limit be exceeded, (EGT, CHT, CHT COOL RATE, SPAN, RPM, Hi/lo Oil Temp/Pressure, Hi/Lo VOLTS and TIT) a recording of all engine parameters is taken. The duration and maximum value of each exceedence, along with the exact time and date are recorded.

Alarm conditions have display priority, and all of the EDM instruments display the type of alarm and its value. Twin engine aircraft require two displays and two computers, but JPI now has a single 3 1/8" unit available for twin engines, that displays both engines on one display simultaneously.

Benefits of Recording:

The bottom line on data recording is that it is a very powerful tool. The EDM-700 makes long term trend monitoring easy and easily verifiable on paper. The real benefits are longer engine life and reduced engine maintenance costs. A complete diary of an aircraft's flight profile is now available for analysis by yourself or JPI. This permanent and unalterable record will highlight individual performance variations and allow for corrections before damage occurs. How many time has the going got rough and later, you wondered what affect it had on the engine? Engine warranty claims and resellers will look for the EDM-700's total recorded hours.

Peak EGT

One of the most important-yet misunderstood-controls on your aircraft is the mixture control. The most effective way to achieve optimal fuel/air mixture is by measuring the temperature of the product of combustion, exhaust gas. As you lean the mixture, the Exhaust Gas Temperature (EGT) rises as the excess fuel is decreased and the combustion is more complete. By measuring the EGT of all cylinders simultaneously, you can determine the first cylinder to peak. Manually by trying to watch all EGT's at the same time is very difficult. The EDM-700 gives you help in three ways: (1) "LeanFind" identifies the first cylinder to peak, (2) "PeakFind" captures the peak value, eliminating over shoot and (3) JPI's fast-response probes are the keys for the LeanFind mode to function properly. The diagram above shows that as the mixture is leaned from full rich position, the EGT increases as the excess fuel decreases. Leaning must stop on the first cylinder to peak, and not the hottest. If you lean to the hottest, some cylinders will be too lean of peak, and could cause detonation

Probe Response

Fast probe response is very important for the LeanFind mode to function properly. Probe response is the time it takes for the probe to react to an engine temperature changes. Response time is primarily affected by (1) Probe mass--low mass for fast response, (2) type of Thermocouple junction--grounded is faster, and (3) Sheath material--copper is fast, stainless steel is slow (like JPI's CHT copper tip probes). JPI probes are fabricated out of a space age material, Hastaloy-X, that can withstand the harsh sulfur atmosphere of high exhaust gas. JPI probes are grounded to eliminate a layer of insulation that would slow the probe response time. At JPI we have found that while leaning an engine, the EGT can change at a rate of over 15 degrees F per second. With slow response probes, you will not be able to find peak EGT. If the EGT increases faster than a slow probe can respond, peak overshoot will occur, giving a false or flat peak indication with engine sputter.

Thermocouple Probes JPI temperature probes are type K thermocouples. Thermocouples are the simplest and most reliable remote temperature measurement transducers available. The principle of operation is based on a property of metals that a bimetallic metal wire with a different temperature at each end will develop a small voltage along the length of the wire proportional to the difference in temperature. The EDM-700 measures this voltage, corrects it for non-linearity (linearized) of the thermocouple material and display the temperature. A reference junction corrects for the ambient temperature at the instrument.

Fuel Flow Option

After extensive testing of many fuel flow measurement products, JPI engineering concluded that all the systems presently on the market were not capable of supporting the EGT leaning process due to their slow response times. JPI has developed a fast response system that permits you to simultaneously view peak EGT and minimum fuel flow. As the pilot leans the engine he will see simultaneously fuel flow and peak EGT. Enrichen the engine 20 degrees and note the fuel flow in Gal/Hr. Their will be an optimum EGT enrichment vs. fuel flow for your engine, giving maximum range and power. The EDM-700 Data Port will include fuel flow data in the data stream. A throttle change with GPS will display fuel required to next GPs fix. Don't be worried about having too much data to deal with, because the EDM can be set to monitor EGT or Fuel Flow only or both simultaneously with the flip of a switch. The bar graph is always displaying EGT/CHT and if the EDM is set to read Fuel flow only a temperature alarm will be displayed immediately. This is not a fuel pressure gage, but a true fuel flow turbine transducer mounted in the fuel line. The fuel flow option takes no additional panel space and is STC'd for most aircraft.