Starting the 912iS

For now I'm just going to give up on reading the on-line 912iS Installation Manual and break down and ask, "What switches are required, and how do you start this fancy engine I'm planning to install?"

The manual has page after page of discussion of the intricacies of wiring harnesses but it all seems directed to the harness that comes with then engine. I would have been so nice to find a, "Here is What the User Supplies" chapter.

Along with the Firewall Forward kit, I purchased these engine related switches from Kitfox: Master, Lane A, Lane B, Fuel Pump 1, Fuel Pump 2, and a shrouded push button starter switch. With a simpler engine, that should do the job. At this point I'm not sure the set meets the requirement for the 912iS.

There are a few of us thrashing around at this stage of the project. It would be very appreciated if someone with an iS installation could post a simple description of the starting sequence and perhaps a schematic of the user supplied wiring.

I suppose I'm feeling more than a little overwhelmed facing the complexities of this engine combined with the G3X Garmin system. This needs to get all ironed out before holes are drilled in the instrument panel.

Hey Carl,
Kitfox sent all the switches one needs to operate the 912iS. They sent toggle switches. I have replaced those with Rocker switches. I may have to replace those that operate the fuel pumps with ones that candle handle the specific current that operate those. I have inexpensive switches since I thought everything was just a ground switch associated with the VPX. Stand by for information about getting the pre-made HIC connection wire bundles as soon as Ryan figures it out. If you look deep at the Rotax manual in the chapter covering Power Plant install you will see the wiring that will be needed. Refer back to my EFWD build thread. The latest entries pertain to that.

I ordered a set of those pretty round switches from Kitfox and specified how many I wanted, so the default switches weren't include with my Firewall Forward kit. Debra may have doubled check my switch count or, oh dear, assumed I knew what I was doing.

Meanwhile, I'm staying busy covering a wing and thinking longingly of the days of mixing Hysol.

Hi Carl,

I reckon you're almost there with the switches but still need a backup battery switch and (possibly) a start power switch.

Without wishing to perfect the art of egg-sucking I will just assume you know nothing of the thinking behind the engine and apologise when I insult your intelligence.

The engine needs electricity to power the computers, fuel pumps etc or it doesn't run (or start). After start it makes its own electricity (assuming all works as advertised), so we only need to provide power for starting. This is why there is a start power switch (or not if you have a timed relay, as I will). Rotax talk of this being a DPST switch but one that you hold in position during start. That seems a bit silly to me but I suppose it's to get round the person who is going to forget to turn off the start power if it's a 'normal' toggle switch. This switch needs to be rated 5A at 28VDC. So, you'll be (holding) that start power switch on during start until the generators are online and it can do its own thing.

The backup battery switch is there to provide electricity to the same computers, fuel pumps etc if both generators fail. Without electricity the fan stops. The backup battery is a DPST switch rated at 20A @ 28VDC. One side of the switch connects the aircraft battery to the engine, the other side of the switch connects the engine (EMS) earth to the airframe earth. Hopefully you'll never need this switch but Rotax say it's supposed to be guarded.

Once you have a look at the diagrams you'll see it's really not too difficult and the switches are merely switching wires between, for example on the Fuel Pump 1, HIC A Pin 3 and HIC A Pin 9. You simply wire one pin to one terminal and the other pin to the other terminal. The Lane and Fuel Pump switches all work this way. The Backup Battery switch is as discussed above and the Start Power works in a very similar manner but connects a couple of fuse box wires instead of HICs.

The Lane switches (x2) need to be SPST and 7.5A @ 28VDC

The Fuel switches (x2) need to be SPST and 10A @ 28VDC

I bought some beautiful rocker switches from Aero Rockers which are rated at 20A per side (of the switch), so can be bridged to give a 40A switch. I had some lovely custom engraving done for the LED lights that illuminate when the switch is on. I was extremely pleased with my rocker switches and now find that I'm not going to be able to use them and get the other things I want on the (compared to a Kitfox) quite small panel of the Eurofox :( I do, however, own some great rocker switches and have made a very helpful friend of the knowledgeable supplier. Instead of my rockers I am now going with 20A @ 14VDC DPST toggle switches throughout. This means I can use use any switch for any of the Rotax jobs.

As I mentioned in another thread, I won't be using the start power switch but a clever device manufactured by a chap in the UK. Basically, when power is applied the device starts a 1 minute clock that connects the start circuit to the battery. After start and 1 minute the circuit is cut, the engine makes its own wiggly amps and I don't have to either hold a start power switch or remember to turn one off.

Assuming there's no fancy start timer gizmo, then the start sequence goes something like (if I can remember correctly):

Lane A on....light on....light off
Lane B on....light on....light off (that's it doing a self test)
Fuel Pump A (1) on
Set throttle at ?? %
Start power switch on/hold/don't bother if you're me
Press the start button and marvel at the noise :)

My aircraft is still a twinkle in it's owner's eye but I've had so much time on my hands that I've done a bit too much looking into things. Please treat all my comments in the knowledge that I don't have a 912iS running but I've read the manuals a fair bit and talked to people that know the engine inside-out :D

The electrical installation for the 912is is no problem. The kitfox firewall forward kit instructions include a wiring diagram which is much easier to understand than the Rotax diagrams. The only issue is which engine monitoring system are you intending to use. When I did mine the shunt for monitoring the B alternator came with the engine monitor (advanced 5600) and both the Advanced manual and the Kitfox instructions covered its installation.

Starting is a joy. Just apply start power, turn 1 fuel pump on, turn both lane switched on, set throttle for outside temperature, press start switch and it starts. And it starts every time.

Two very helpful posts that have really cleared things up for me. After reading these straightforward explanations, and not finding the start sequence described in the Rotax manual I was reading, I went back to their site and found the Owner's Manual. I had previously downloaded the Installation Manual which is a much more in-depth document - more of a service manual than what is needed for installing the engine. The Owner's Manual is a more straightforward document. Eddie referenced the Powertrain section. It is very readable in the Owner's Manual but a much more complicated slog in the Installation Manual.

Thanks for going to the trouble of including all of those details Paul. Looking at the wrong manual, I hadn't noticed the requirement for "Start Power" switch or button. Can you post a link or contact info for the guy who makes the starter timer? I didn't see a contact in the other thread and would like to consider it. I did come across a thread in the Rotax Owner's forum where a Kitfox builder (Richard) put the start power toggle just to the left of the throttle. His sequence is: Right hand on the throttle, thumb under start switch, and left index finger on the start button. Engine starts, release both switches and adjust throttle.

I was thinking the Backup Battery switch brought a second battery online - something I wasn't interested in lugging around. Now I see it is a way to provide backup power from the main battery to the EMS. This Owner's Manual is such a nice read compared to the Installation tome!

The Cambridge CAV 13 Status Monitor looks interesting. The manual is on-line but I'm having a hard time getting a reply to emails asking for pricing.

I did the inventory of when the Firewall Forward kit arrived a few days ago but hadn't opened the manual. Neville's comment about the Kitfox wiring diagram sent me to the included build manual where things are spelled out fairly clearly.

Glad things are getting clearer. I, too, was over-awed but it seems to make a bit more sense now.

So, there are two guys involved with the gadgets I've talked about.

The first, Steve Williams, is the man in the UK who puts together the Eurofox for those who buy the factory-built kit. He has a 912iS in his Eurofox and came up with the idea of the starting timer box. Basically it takes the place of your start power switch and is really a direct replacement. For my system (and just about every Eurofox with the iS) I'll have a 3 position key switch (mainly for security or else a 3 position toggle switch can be used). From OFF I go one click on the switch and that's my master power for the battery bus. The next click of the switch is the one that starts the one minute start timer. Very simple :D I'll have the start push button on the left of the panel so I can push that with my left finger and have my right hand on the throttle. No need to be holding spring-loaded start power switches in the on position. Of course, as I said before, you could use an on/off switch for start power but (a)it's not strictly what Rotax says and (b)just remember to turn to off after start. Steve is not an easy man to get hold of and is, I am informed, not the greatest of email repliers. His mobile number in the UK is 07813 138 897, so you'll have to do the +44 bit and miss off the first 0. The Eurofox email address is: eurofoxuk@btinternet.com. This will likely be replied to by Roger (sales) but if you explain that Paul the pesky Brit of Oz has put you onto Steve's starting timer then I'm sure he'll be able to steer you straight.

John Barrott is the man behind the status monitor (and wiring looms) and is a 912iS electrical guru. He also has an iS in HIS Eurofox :) He's normally brilliant at replying to emails, so I can only imagine he's vacationing (as you chaps say) or somesuch for him not to reply straight away. You should be able to get him through info@cambridgeavionics.com If you don't have any luck with this then let me know and I'll ask him if it's okay to give you his personal email address. The last two status monitors he had were advertised on eBay. I nabbed one of them because he thinks the price may have to go up a bit on the next batch. They're not cheap. I paid about $640 but I think they're worth it. That, of course, is a very personal call and I will not try and influence you either way....you can read all about it on the website: www.cambridgeavionics.com

I will re-iterate that I am not advertising for these guys and have no vested interest in either of their products other than me getting them for my installation and thinking they're good bits of kit. Both blokes also know shed-loads about the engine and the electronics behind them, so they're good people to know and ask questions of.....if Steve ever replies :D

Thanks for all that Paul. Im with Carl on all this stuff. Even not getting replies from the UK on the wiring harness.:D
If I may ask. What is with the "required" Back Up battery? Nobody has told me I have to have a "back up" but now I have had two references to that in the past week. One in your explanation and one from the UK wiring diagram and description. I went to Aircraft Spruce to ask and I am told it is optional.
Eddie

Hey, an iS question I can answer by referencing page 4-3 of my newly downloaded Owner's Manual - 4.5) Failure of the EMS power supply.

If the EMS power source (alternator A) fails the engine switches over to the second power source (alternator B). As long as alternator B is providing energy, there isn't a problem. Should alternator B fail, the engine will quit. The backup battery switches brings your aircraft battery into the EMS power circuit to avoid this potential failure.

The start sequence is pretty straight forward and simple.. We actually had a timed relay early on and decided against it as a normal practice. Without getting too much into the "argument" of either.. we chose to stay with a single switch that is on-off-(mom) DPDT switch. The momentary is for normal starting.. the on is the backup power... works well and to put emergency power direct to the engine requires a single switch.. it is included with your fwf kit. Your wiring diagram for that switch may be incorrect.. so please email me directly for an update.

Master - on
Fuel Pump - on
Throttle - crack
Momentary - hold
Lane A - On - wait for light to go out
Lane B - On - wait for light to go out
Start Button - push to start
After start - release momentary
RPM to 2400+ until generator comes online then reduce to idle.

John,

Thank you for providing your experience with the timer and for the definitive starting sequence. You wouldn't think we could get ourselves in a tizzy about what should be a simple thing. But it's a long way between drilling holes for switches in the console and actually wiring the engine. Sometimes book learning doesn't do.

Email request set for wiring diagram.

I have 300plus hours on the 912is now. I installed using the Kitfox FWF kit for the 912is and used all their switches etc. Yes, you need to read both the Kitfox and Rotax manuals in order to cross reference and understand the system - but it is not difficult. Yes, the Rotax Operations manual needs to be referenced for the start sequence but it is very clear in there. I installe dthe switches along one row to represent the start sequence. The momentary power and start switch is really easy and a 'non-even't really - I have no desire or need to replace it - it is certainly easy and not a 'pain' to use.

I think that the language used to describe the 912is system takes a little getting used to and Rotax does need to make its manual more 'plain english'. EG. I, like others, got confused by the meaning of the' back up battery switch'!

But like the others have said, what a nice engine! starts first time every time - hot, cold whatever!

Good luck and happy to share photos or diagrams if needed.

cheers

ross