A Neeewwb Question

[Philip Shiflett]

Philip here...

Build is Just Aircraft Escapade with 130 engine.  Standard wiring with some additions.

Question:  What is best method for quick shudown of Viking 130?

ECU is direct powered so killing battery relays will kill ECU and landing lights and everything else.

Sent this photo for Jan, shows header tank install in rear bulkhead area of JA Escapade, also note battereis located in tail.  Both header tank and batteries were located aft to help with weight and balance.  Escapade is in tali wheel config, this helps counter weight Viking 130 engine.

 

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[Loren Warner]

To shutdown a Viking 130 quickly, you need to disconnect the battery(s) and alternator. We use toggle switch to open battery circuit, and starter switch to disconnect alternator. Note, some prefer a stand alone alternator switch. With regards to your header tank picture, I'd get rid of the loop in the fuel hose. Also, if not already planned, I suggest you install a header tank sample/drain valve.

[Philip Shiflett]

Will get rid of service loops. Drain valve is in place already.

As for killing battery and alternator, that kills the ECU. That stops the engine. It also kills my landing lights and other instrumentation. That wouldn't be good on a final at night with a prop/PSRU problem. Is it a big deal to connect the ECU power to the ignition switch? I do understand the necessity of maintaining ECU power. The switch provided does maintain in the start and run position and has a closed transition between run and start. Is the switch reliable and have a decent MTBF?

[Loren Warner]

One of the reasons to avoid having a stand alone ECU switch is to minimize failure points. As soon as the engine stops, you can always turn the battery(s) back on if needed.

[Loren Warner]

I just noticed your question "Is it a big deal to connect the ECU power to the ignition switch?" The ECU should be powered by the main power bus, not the ignition switch. The ignition switch should only be to start the engine and possibly turn off alternator. As for reliability, you can use whatever switch you want. Are you using Viking Aircraft Engines suggested wiring diagram?

[Viking Aircraft Engines]

It should be very difficult to shut down the engine. Right now you would have to throw 2 batteries overboard and also turn the alternator switch off.

This part needs to stay.

Now, you would NEVER use the ignition switch to power the ECU. These switches are not reliable enough.

This is what is recommended. Now if someone insists on wire it differently, there is a wrong and correct way.

The ECU has a large and smaller AWG wire. The larger wire would be wired as shown on the diagram and the smaller wire is used to turn the EVU on / off.

Immediately there are more failure points.

[Philip Shiflett]

Thanks for the input on the ECU power.

As to the question of using the Viking diagram in this AC: Yes, it is the same, with additions for the instruments, lighting and comm equipment.

As I do plan to fly this plane at night, I would like to be able to maintain lighting and instrumentation in the event the engine needs to be shutdown.

If I understand Jan's comments correctly, the ECU could remain connected to the bus and the smaller of the wires could be switched to stop the engine.

I do understand this does increase chances of failure due to additional circuit elements.

As an alternative shut down method, how long does it take to stop the engine if the fuel pumps are switched off?

Thanks

[Viking Aircraft Engines]

The issue in regards to shutting down the engine with the “high” pressure fuel pumps is that you would starve the “higher” pressure mechanical pump and empty the fuel rail of pressure, making it harder to re-start.