Peter wrote:
The control cable which is a perpetual issue on Lyco/Conti installations is the prop governor cable, which is right at the front.
Not on all installations, such as the typical Lyco IO-360 that mounts the prop gov on the rear acces. case.
The original post really is irrelevant since Lycoming, Continental and [ I assume] Rotax all supply bare engine with little or no instrumentation or accessories so it’s all up to the aircraft man. to sort out the configuration, accessories and instrumentation.
@Michael: yes, I hinted as much about the R/R and fuses (I assume those funny black things to be well-encapsulated fuses, probably of the automotive type) being mounted on the hot side of the firewall. It is bad enough to have fuses instead of circuit breakers, but to have them completely out of reach during flight, for no good reason, is itching for trouble.
Then again, as I pointed out, the four six-way connectors from the flywheel-powered induction coils to the ignition boxes are an integral part of the engine as supplied from the Rotax factory so these could be questioned – but again, I never heard of any issue with them.
europaxs wrote:
Peter, I think we Rotax-jockeys who are commited to VFR do more often have to fly through rain than you IFR on top
Haha! IFR Jockeys can only do it on top… VFR Jockeys can take the rough AND the smooth 
@Peter: from what plane are your pictures? Some details (the amount of tie-wraps, for one example) seem to suggest an over-zealous homebuilder – I can’t help suspecting a bit of Deutsche Gründlichkeit..? The markings on the cabling and near the fuses also seem a bit overdone.
I went through my pics and have no others of that one, so I don’t know.
I have seen quite some issues with the internal generator on the Rotax, it’s a poor design which doesn’t give a clean output. A big capacitor is used to solve this, however many installations use thin wires and long runs, which just doesn’t work for this fast rising high peaks. Damages I have seen where all with avionics including switched mode power supplies, damage which likely is caused by these transients.
Jan_Olieslagers wrote:
Some details (the amount of tie-wraps, for one example) seem to suggest an over-zealous homebuilder – I can’t help suspecting a bit of Deutsche Gründlichkeit..? The markings on the cabling and near the fuses also seem a bit overdone.
I don’t see what is wrong with this? Actually I think it is very good, and is also the way I do install new equipment, every wire marked, and use a quite some tie-wraps or lacing cord. I do prefer lacing cord and will use this most of the time. It cost a little bit of extra time, but gives better support, looks better in my opinion and isn’t sharp. I really hate tie-wraps which have been cut to become like a nife. You see this all the time, even at places with easy access. I really don’t understand why someone would work like that.
I see quite some installation which have 1 tie wrap over 25-50 centimeter, some even more. The wiring isn’t supported at all then, which makes it more likely that it gives strain on the strain relief on the connectors. I thinks strain relief on connectors should be used as a safety factor, not use it to suspend wiring all the time. Should I wire fail, or should you have to troubleshoot, then these marked wires will speed up troubleshooting. This safes a lot of time, while the expense of doing it right the first time is only little. It will save money on the long run.
Jesse wrote:
it’s a poor design which doesn’t give a clean output. A big capacitor is used to solve this, however many installations use thin wires and long runs, which just doesn’t work for this fast rising high peaks
If anything, long thin wires should dampen fast rising transients.
Jesse wrote:
Damages I have seen where all with avionics including switched mode power supplies, damage which likely is caused by these transients
How do you know? Or is this conjecture? Switch mode power supplies usually generate quite some transients on their own, furthermore they typically have a huge input voltage range, and thus quite some headroom for transients and “dirt” coming their way from the outside…
It probably depends on where the capacitor is. If it is at the start of the long wire then you get a poor transient response.
Also I am sure some voltage regulators have marginal stability. It’s a crude system – controlling the voltage by varying the field current – which is normally done using hugely sub-optimal control loop parameters because of the delays in the system. Long wires to the battery are not going to help.
IME switch mode power supplies are very easy to blow up with a transient. Especially the one you get from the starter motor when starting.
The cap that Jesse mentioned has nothing to do with transients – it is a big elco, and elco’s do very little about transients aka spikes. Its raison d’être is that the regulator always needs to “see” something that behaves more or less like a battery, also if the charge fuse blows, lest it destroy itself. Thus, the elco must be before that fuse, and is generally mounted close to the regulator.
Said elco is indeed a standard on all Rotax installations, but recommendations for its size vary – I’ve seen everything between 4700uF and 22000uF.
and @Peter: the Rotax has NO field regulation – the 11 coils are excited by permanent magnets, fixed to the flywheel. Regulation is (usually) by thyristors in the rectifier bridge.
elco’s do very little about transients aka spikes
That depends on its ESR, the source impedance, etc.
