System Checkout – Initial Start Up

First engine start is an exciting time. As with the installation checkout, refer to the EM-6 Manual for trouble shooting guides.

As each SDS installation is unique, I suggest that you create a “First Start Checklist” that details each step in the startup process. Switch / knob positions should be defined and checked. When doing something for the first time it is easy to make a mistake. During my first start, I missed checking all circuit breakers were “In”. I had pulled the coil breakers when doing some earlier tests and failed to reset them – starting was not going to happen!

System checkout is straightforward. The guide below details the process I used and highlights a few common oversights that can lead to problems. However, the SDS EM-6 manual contains an extensive troubleshooting guide that can resolve many more common installation problems.

Initial System checkout

There are a few of concepts you should keep in mind / understand before performing these tests. These concepts are very important to understanding how the tests work.

  1. Each ECU controls a coil pack which in turn controls a set of spark plugs. Typically ECU # 1 controls the coil pack that controls the top spark plugs and ECU # 2 controls the coil pack which controls the bottom set of spark plugs. Normally, this convention is not changed when installing ECUs.
  2. The ECU select switch (1, 2 or both) only changes how the fuel injectors are controlled. It DOES NOT change the operation of the coil packs. This switch changes the injector relay box and does not actually impact the
  3. When a single ECU is selected, the selected ECU controls all 6 injectors. When โ€œBothโ€ ECUs are selected, ECU 1 controls injectors 1,2 & 3 and ECU controls injectors 4,5 & 6.
  4. Again, keep in mind that the ECU selector switch does not affect the operation of the coil packs and the operation of the spark plugs. Therefore there should be no change in the engine RPM when ECU 1, ECU 2 or both ECUs are selected.
  5. The COIL switch determines which coil packs are active : 1, 2, or both. If only coil pack 1 or coil pack 2 is active, there will be a RPM drop as only one set of spark plugs is active. This is analogous to a mag drop in a conventional magneto controlled engine.

Start the Engine

Start engine and bring to idle RPM.

If the engine is running rough or fails to start, consult the trouble shooting guide in the EM-6 manual.

ECU Operation Test

This test confirms ECUs are operating correctly and need only be done as part of initial system checkout. It should not be done as part of a pre-flight test.)

  1. Select ECU 1. Pull circuit breaker for ECU 2. Engine should continue operation with a 75-100 RPM drop.
  2. Reset circuit breaker for ECU 2.
  3. Select ECU 2. Pull circuit breaker for ECU 1. Engine should continue operation with a 75-100 RPM drop.
  4. Reset circuit breaker for ECU 1.

Notes: When ECU 1 or ECU 2 is selected only the selected ECU is controlling engine injectors. Pulling the circuit breaker for the other ECU takes that ECU (and the associated coil pack) offline and results in rpm drop as only a single set of spark plugs is operational.

If the ECU select switch is on the BOTH position, injectors 1-3 are controlled by ECU 1 and injectors 4-6 are controlled by ECU 2. Consequently, if either ECU circuit breaker is pulled, then engine will be running on only three injectors causing a very rough engine. This is not recommended.

Once these checks have been done and issues (if any) resolved, you can proceed as desired with any other checks you may wish to perform.

Pre-flight Runup โ€“ Normal Operation

The tests below should be done before each flight as part of the normal run up process.

The runup process for the SDS system is similar to the process for a conventional dual magneto aircraft. Once oil temperature has reached 120F+ the following steps are suggested:  

  1. Ensure both Coil Packs are on
  2. Ensure ECU select switch is on Both
  3. Throttle up to 2,100 rpm

Coil Pack Test (this is analogous to a magneto check)

  1. Switch Coil Pack 1 off. A 75-100 RPM drop should be noted.
  2. Switch Coil Pack 1 On.
  3. Switch Coil Pack 2 off. A 75-100 RPM drop should be noted.
  4. Switch Coil Pack 2 On.

ECU Injector Control Test (Confirms each ECU can control all 6 injectors)

  1. Select ECU 1. No change in engine rpm / operation should be noted.
  2. Select ECU 2. No change in engine rpm / operation should be noted.

Fuel Pump Operation Test

It is imperative that both fuel pumps are operating correctly for safe flight.

Switch both fuel pumps on and note fuel pressure.

  1. Switch fuel pump # 1 off โ€“ there should be only a minimal change in pressure.
  2. Switch fuel pump # 1 on and number 2 off. Again, the fuel pressure drop should be minimal

Fuel flow check

Check that fuel flow is nominal. I typically see a +/- 8 GPH fuel flow during a 2,100 RPM run up at 4,000′ ASL.

Prop Check

  1. Cycle prop in accordance with prop manufacturer recommendations.

After completion of these tests, close throttle return engine to idle RPM.

If any anomalous behavior is detected, the underlying issue(s) must be identified and corrected before flight.

Before Take Off Checks

  1. Ensure all circuit breakers are โ€œinโ€. Abort take-off if any circuit breaker(s) have failed and resolve cause before further flight.
  2. Ensure ECU select switch is on โ€œbothโ€.
  3. Ensure Coil Packs 1 & 2 are both โ€œonโ€.
  4. Ensure Fuel pumps 1 & 2 are both โ€œonโ€.
  5. Ensure LOP (lean of peak) is โ€œoffโ€.
  6. Ensure mixture knob is set to desired position.
  7. Complete any other required pre-takeoff checks.