Tips to Review on Shadin Fuel Airdata System Installations

Sep 17, 2026

Tips for reviewing installations of Shadin Fuel Airdata Systems, focusing on Pitot-Static plumbing compatibility, correct wiring for digital ADC/Digidata units, and proper handling of OAT probes. The guidance includes voltage and continuity checks for specific connector pins, resistor substitution for OAT testing, and Micro-ammeter scaling rules. It also addresses lack of serial communications with GPS/Loran, required system heading power connections, Digidata warm-up troubleshooting, and diagnosing “No Fuel Flow” by verifying transducer power, signal inputs, and grounding.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages2

Reading Time5 min

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Tips to Review on Shadin Fuel Airdata System Installations

Pitot-Static Plumbing

Digital ADC/Digidata Fuel Flow Transducer Power

OAT Checks and Testing

Serial Communications With GPS/Loran

Power and Heading Wiring (No Heading)

Digidata Constant Warm Up Message

Digidata P/N 912802 No Fuel Flow

6831 Oxford Street,St.Louis Park,Minnesota 55426,U.S.A.Technical Support Telephone:(800)388-2849 Fax:(952)924-1122EMAIL:repair@shadin.com # Tips to Review on Shadin Fuel Airdata System Installations 1) Pitot-Static Plumbing:Be aware that Fuel Airdata Systems connected to differentPitot-Static systems from other aircraft equipment may have results that do notagree with that equipment. 2) For digital ADC units that tap signal from an existing aircraft fuel flow system,DO NOT USE FUEL FLOW TRANSDUCER POWER FROM PIN1 ORPIN 9 OF J-1.For digital Digidata units that tap signal from an existing aircraftfuel flow system DO NOT USE FUELFLOW TRANSDUCER POWERFROM PIN 3 OF P-1. 3) No OAT on the ADC or Digidata; a. Check for 5 volts to the red wire on the OAT probe. b. Check for continuity to pins 14 and 15 of J-1 of the FADC from the OATprobe.For the Digidata,check continuity to pins 8 and 9 of P-3 from theOAT probe. C.Substitute a 15K ohm 1%resistor for the OAT probe across pins 14 and15 of J-1 on the ADC or across pins 8 and 9 of P-3 on the Digidata.TheOAT should read approximately 5℃. d. If step c.is okay,then wire the OAT probe directly to J-1 of the FADC to test it.For the Digidata,wire the OAT probe directly to P-3 to test it. e. Insert a Micro-ammeter in series with one of the OAT probe leads.273 μais equal to 0℃.The scaling is linear with 1℃=1μa. Tips to Review on Shadin Fuel Airdata System Installations ## 4) No serial communications with the GPS or Loran; a. Check to be sure that step 2 in this document was complied with. b. Check the packing slip from the distributor for the system configurationand verify that it is correct for your application. ## 5) No Heading; a. Make sure there is a 26v 400 Hz power supply in the system for H and C. b. Z and C(AC common)are tied together on the Digidata.In the FADC,Zand C(AC common)must be connected together at the source (bootstrap). ## 6) Digidata...Constant Warm Up Message; a.Disconnect P-3(This will let you know if anything in the Heading or OATcircuits is loading the system). b. Out of the aircraft...Apply 14 to 28 volts to pin 1 and Ground to pin 2 ofP-1....f the Warm Up message continues,return the unit to Shadin forrepair. ## 7) Digidata P/N912802...No Fuel Flow; a. Check pin 3 of P-1 for transducer power…approximately 15 volts. b. Check pin 15(Left transducer signal input)for 5 volts(open circuit). c. Check pin 13(Right transducer signal input)for 5 volts(open circuit) d. If 5 volts is present at 13&15,tap either one or both rapidly to ground.This action should present a tenth or two of fuel flow on the display. e.The transducer grounds (black wire or pin C)should be returned to pin 11(left or single)and pin 10(right or rear).

FAQs

Why is Pitot-Static plumbing compatibility important in these installations?

Fuel Airdata Systems connected to different Pitot-Static systems from other aircraft equipment may produce results that do not agree with that equipment.

What should be checked when there is no OAT on the ADC or Digidata?

Verify 5 volts to the red wire on the OAT probe, then check continuity from the OAT probe to the specified pins on J-1 (ADC/FADC) or P-3 (Digidata). If needed, substitute a 15K 1% resistor across the relevant pins and expect the OAT to read approximately 5°C.

How can “No Fuel Flow” be diagnosed on the Digidata P/N 912802?

Check transducer power at pin 3 of P-1 (about 15 volts), confirm 5 volts at pins 15 and 13 for left/right transducer signal inputs, and if 5 volts is present at both, rapidly tap either or both to ground to trigger a brief fuel flow display. Ensure transducer grounds return to pins 11 and 10 for the appropriate channels.

Sep 17, 2026

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