Lycoming O-360 Shut-down techniques
It gets hotter after start, quicker, due to my aggressive leaning practices. It gets hotter after landing than it would if I set the mixture to full rich.
I do have to laugh. What is the very purpose of the procedure quoted by the OP? The very purpose?
To make the engine (actually particular bits of it and EGT).... hotter.
I can achieve that (and keep the plugs and valves clean) without having to blast away at 1,800 rpm in some pre-shutdown ritual.
(Where are you located, BigEndBob?)
I do have to laugh. What is the very purpose of the procedure quoted by the OP? The very purpose?
To make the engine (actually particular bits of it and EGT).... hotter.
I can achieve that (and keep the plugs and valves clean) without having to blast away at 1,800 rpm in some pre-shutdown ritual.
(Where are you located, BigEndBob?)
Must be different fuel in Oz. Certainly my experience of engines in the 152 size needed plugs pulling before 50hrs. We have been operating a PA38 it lasts 50 hrs, even with leaning, quite a bit of lead in plugs.
Cessna 152 O-235-L2C and N2C are pretty solid engines, never really had any issues with ours if the engine was healthy and they almost always made TBO without much issue. A lot of the flying was circuit work and training area with students, lots of taxiiing and idling with only the odd case of fouling and we are talking thousands of hours a year between several 152s. To put in perspective for each hour of running time .3 was on average ground time, so every 100 hours airframe the engine was running 130 hours, that 30 being low power ground handling. Compared to the Arrow fleet where .1-.2 ground time per hour was average due to the navigation focus on its use. Maintenance was conducted on air-switch. I know early on C152 had a reputation for fouling issues, but I assume engine modifications and carby changes over the years, new plug technologies, may have remedied this. There were definitely more than one carby options for the 152 at least.
O-360 shutdown
Actually I had forgotten about the Grob-115C2, which uses the O-360 engine, again a bit of leaning on taxi would remedy any fouling if the engine was healthy. For the engines on the way out a bit more of a run pre take-off might be needed to clear plugs. Never heard of the idea of running at 1800rpm prior to shut down, really not sure it would prevent that much fouling as it would just start building again the next taxi out, as the engine would be at it's coldest then. I do remember sometimes quite a long idle warming the engine as well after start if it was first flight, as LB said some leaning would help it warm as well as preventing fouling.
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Well I’ve got a question guys. And I hope that it’s okay to put here. How much damage do you do to one of these engines, if you shut it down with the key, rather than with the mixture. I recently have found that when me and my friend go flying, that for short stops, such as fuelling, we turn the engine off with the key. And the longer it stops, so if the plane is gonna be parked all day or if we are going to be moving away from it for a long period of time, we shut it down with a mixture. How much damage is it doing by turning off by the ignition rather than the mixture.
Hey Mr Pinky,
Is there a 'computerised' Flight Manual...??
I mean, today's Aces' wouldn't read a lowly 'manual' would they?
I mean, If its NOT 'computerised' then it simply cannot be 'right'?
P M Sent.....Melly Chlistmas,,,,,
Is there a 'computerised' Flight Manual...??
I mean, today's Aces' wouldn't read a lowly 'manual' would they?
I mean, If its NOT 'computerised' then it simply cannot be 'right'?
P M Sent.....Melly Chlistmas,,,,,
Well I’ve got a question guys. And I hope that it’s okay to put here. How much damage do you do to one of these engines, if you shut it down with the key, rather than with the mixture. I recently have found that when me and my friend go flying, that for short stops, such as fuelling, we turn the engine off with the key. And the longer it stops, so if the plane is gonna be parked all day or if we are going to be moving away from it for a long period of time, we shut it down with a mixture. How much damage is it doing by turning off by the ignition rather than the mixture.
It's actually good practice to occasionally make sure that that the 'OFF' position on an ageing ignition switch in an aircraft with ageing wiring actually grounds both magnetos.
I have to ask, what is the underlying logic of using the key for 'short' stops and the mixture for 'longer' stops? I'm guessing that the engine involved is an injected one that's hard to start when hot?
Not a good idea to shut down using keys with the traditional updraft carby, that will leave residual fuel in the carby venturi and induction area creating a back-fire risk on restart and fire hazard, as well as a kick risk if the prop is manipulated by hand while moving around. So no direct damage risk, but a few other risks that you need to be aware of. Obviously shutting down with mixture ICO will mean every last drop of fuel/air mix in the induction system will be sucked through the engine and most likely burnt as it dies as the spark is still happening.
The same risk of unintentional kick from manipulating the prop is there with fuel injected as well, as turning off the keys just stops ignition, so the fuel system is still charging. Have to remember vapor locks are caused by hot gaseous fuel in the system, not hot air, so residual fuel in the lines is the enemy, not air.
Not a bad rundown on what causes vapor locks and simple remedies, this comment was good;
The only addition I'd make to that is knowing which tank the return line flows to, if you have the other tank selected and the return tank is full you might end up pumping fuel overboard.
The same risk of unintentional kick from manipulating the prop is there with fuel injected as well, as turning off the keys just stops ignition, so the fuel system is still charging. Have to remember vapor locks are caused by hot gaseous fuel in the system, not hot air, so residual fuel in the lines is the enemy, not air.
Not a bad rundown on what causes vapor locks and simple remedies, this comment was good;
Fred Sweet
Vapor lock also occurs in the fuel control unit and engines mechanical fuel pump. The mechanical fuel pump is easily heat soaked as it is mounted to the case. The electric fuel pump is typically remotely mounted and can still push fuel through the system. You can tell when fuel reaches the injector lines as the fuel flow indicator on many aircraft is located just prior to the fuel distribution block. If you prime the system with fuel mixture and throttle full open, the fuel flow will rise as liquid fuel flow past the fuel flow transducer. Shutting off electric fuel pump immediately after the rise in fuel flow will minimize flooding. At this point starting may still be difficult as the mechanical fuel pump is still heat soaked and can be vapor locked despite getting fuel into distribution lines. Beechcraft have a fuel return line so with the mixture in idle cut off, running the electric fuel pump for 60 seconds, fuel runs through mechanical fuel pump to control unit and back to tank cooling them off. Then a normal start procedure can be used. Many aircraft have a hot start procedure that is effective to the specific model of fuel injected aircraft. In the absence of a specific hot start procedure, if u have flooded engine, try cranking with mixture at idle cut off, throttle full open and gradually bring throttle back till engine fires, then gradually advance mixture. There are many hot start procedures, best is the one in POH if provided
Vapor lock also occurs in the fuel control unit and engines mechanical fuel pump. The mechanical fuel pump is easily heat soaked as it is mounted to the case. The electric fuel pump is typically remotely mounted and can still push fuel through the system. You can tell when fuel reaches the injector lines as the fuel flow indicator on many aircraft is located just prior to the fuel distribution block. If you prime the system with fuel mixture and throttle full open, the fuel flow will rise as liquid fuel flow past the fuel flow transducer. Shutting off electric fuel pump immediately after the rise in fuel flow will minimize flooding. At this point starting may still be difficult as the mechanical fuel pump is still heat soaked and can be vapor locked despite getting fuel into distribution lines. Beechcraft have a fuel return line so with the mixture in idle cut off, running the electric fuel pump for 60 seconds, fuel runs through mechanical fuel pump to control unit and back to tank cooling them off. Then a normal start procedure can be used. Many aircraft have a hot start procedure that is effective to the specific model of fuel injected aircraft. In the absence of a specific hot start procedure, if u have flooded engine, try cranking with mixture at idle cut off, throttle full open and gradually bring throttle back till engine fires, then gradually advance mixture. There are many hot start procedures, best is the one in POH if provided
Last edited by 43Inches; 8th Dec 2021 at 22:58.
Not disagreeing with the substance of what you said, 43, but I do think it’s worthwhile to make the overarching point that this is another circumstance demonstrating why knowledge of the specific systems fitted to the specific aircraft you’re flying is essential. You touch on the reason in what you say about the destination of the return fuel line. Further, this statement from Fred is a bit misleading: “Beechcraft have a fuel return line so with the mixture in idle cut off, running the electric fuel pump for 60 seconds, fuel runs through mechanical fuel pump to control unit and back to tank cooling them off.”
The FCUs on injected TCM engines have a return fuel line. That’s because the mechanical fuel pump is designed to always provide more output than is required for the power setting chosen by the pilot. That applies to FCUs on injected TCM engines whether they are fitted to Beechcraft or any other aircraft brand or model.
Then we have different systems on different serial numbers of the same aircraft type. For example, the return line from the TCM FCUs on some of the early serial number Bonanzas went to only one tank, irrespective of which tank was selected on the fuel selector. That gave rise to the risk you identified. The return line on later serials goes to whichever tank is selected on the fuel selector. That risk is removed on those serial numbers.
Some Bonanzas have a two speed electric aux fuel pump. Some have only one speed. The pressure out of the single speed pump or the two speed pump on ‘HI’ can be sufficient to force fuel through the FCU even with the mixture set to ICO. That results in dangerous puddles of AVGAS when ‘the electric fuel pump’ is run for 60 seconds. I have seen it first hand.
(Research into the specifications for and maintenance instructions for the ‘standard’ FCU on an injected TCM engine showed that the only ICO requirement was that when the FCU is set to ICO on the test bench it lets through less than ’20 drops per minute’ with an input fuel pressure of 10 PSI. The pressure out of the single speed pump or the two speed pump set to ‘HI’ is waay higher than that. Another discovery – which should have been durr obvious but I’m a bit slow – is that the electric aux fuel pump is an airframe component and not an engine component. Why’s that important? Because the engine manufacturers don’t do anything different to e.g. an IO520BA fitted to aircraft X versus aircraft Y, but those aircraft can have different fuel plumbing and electric aux fuel pumps.)
And then there are different kinds of mechanical fuel pumps fitted to the same engine. Some IO520s have an EDP that is connected to the mixture control along with the FCU. Some IO520s have an EDP that has no connection to the mixture control.
In relation to residual fuel after shutting down using the ignition switch, my experience and observation is that on a hot engine any residual fuel will quickly boil off or otherwise evaporate. On an IO520, for example, the valve in the manifold (‘spider’) shuts off fuel to the injector lines when the input from the FCU reduces in pressure due to ICO at idle. But then you can physically hear the remaining fuel in the injector lines boiling and hissing in the lines and venting through the vents on the fuel injectors. The carby mounted in the updraft configuration (e.g. on my 0360) quickly ‘heat soaks’ after shut down. (It's the heat soaking of the EDP on the injected TCM engines that is the primary cause of their hot starting problems. The fuel evaporates in them.)
Cold/er engine? I’d be very wary. But we should always treat props as live and deadly, anyway.
(Don’t get me started on ignition system knowledge…)
The FCUs on injected TCM engines have a return fuel line. That’s because the mechanical fuel pump is designed to always provide more output than is required for the power setting chosen by the pilot. That applies to FCUs on injected TCM engines whether they are fitted to Beechcraft or any other aircraft brand or model.
Then we have different systems on different serial numbers of the same aircraft type. For example, the return line from the TCM FCUs on some of the early serial number Bonanzas went to only one tank, irrespective of which tank was selected on the fuel selector. That gave rise to the risk you identified. The return line on later serials goes to whichever tank is selected on the fuel selector. That risk is removed on those serial numbers.
Some Bonanzas have a two speed electric aux fuel pump. Some have only one speed. The pressure out of the single speed pump or the two speed pump on ‘HI’ can be sufficient to force fuel through the FCU even with the mixture set to ICO. That results in dangerous puddles of AVGAS when ‘the electric fuel pump’ is run for 60 seconds. I have seen it first hand.
(Research into the specifications for and maintenance instructions for the ‘standard’ FCU on an injected TCM engine showed that the only ICO requirement was that when the FCU is set to ICO on the test bench it lets through less than ’20 drops per minute’ with an input fuel pressure of 10 PSI. The pressure out of the single speed pump or the two speed pump set to ‘HI’ is waay higher than that. Another discovery – which should have been durr obvious but I’m a bit slow – is that the electric aux fuel pump is an airframe component and not an engine component. Why’s that important? Because the engine manufacturers don’t do anything different to e.g. an IO520BA fitted to aircraft X versus aircraft Y, but those aircraft can have different fuel plumbing and electric aux fuel pumps.)
And then there are different kinds of mechanical fuel pumps fitted to the same engine. Some IO520s have an EDP that is connected to the mixture control along with the FCU. Some IO520s have an EDP that has no connection to the mixture control.
In relation to residual fuel after shutting down using the ignition switch, my experience and observation is that on a hot engine any residual fuel will quickly boil off or otherwise evaporate. On an IO520, for example, the valve in the manifold (‘spider’) shuts off fuel to the injector lines when the input from the FCU reduces in pressure due to ICO at idle. But then you can physically hear the remaining fuel in the injector lines boiling and hissing in the lines and venting through the vents on the fuel injectors. The carby mounted in the updraft configuration (e.g. on my 0360) quickly ‘heat soaks’ after shut down. (It's the heat soaking of the EDP on the injected TCM engines that is the primary cause of their hot starting problems. The fuel evaporates in them.)
Cold/er engine? I’d be very wary. But we should always treat props as live and deadly, anyway.
(Don’t get me started on ignition system knowledge…)
Very aware of the modern EFI/FCU and all that jazz, was just trying to keep it simple from old tech to new, as there was no mention of type. It does get complicated around newer stuff depending on what 'off' does specifically in your system. An old system was just isolating magnetos and that was that, a new system 'off' disengages a variety of things more like a car. The mixture ICO was more for when the systems were completely separate and new systems you have to dig deep to find out what does what when, best just to follow the POH in that regard unless you are prepared to really understand it (which any aircraft owner should to save money and down time).
And yeah any prop should be treated as live. I remember first flying turbo props and have little hairs stand on the back of my neck every time I was rotating the props for damage inspection with the respect ingrained in me from piston flying.
I remember one instructor many years ago was pulling an aircraft forward via the prop from a parked position to avoid blasting into a hangar on start. Started pulling then realised he didn't have the keys, so asked the student via hand signal with a key twisting motion to ask where they were, student took it as 'give it a whirl' and engaged start with his hand still resting on the prop. Instructor had a fat purple fist for a couple of weeks post event, best possible outcome considering he could have easily lost the hand completely.
PS I would like to know if there are any modern types that do have POH shut down methods of simply turning off the key.
And yeah any prop should be treated as live. I remember first flying turbo props and have little hairs stand on the back of my neck every time I was rotating the props for damage inspection with the respect ingrained in me from piston flying.
I remember one instructor many years ago was pulling an aircraft forward via the prop from a parked position to avoid blasting into a hangar on start. Started pulling then realised he didn't have the keys, so asked the student via hand signal with a key twisting motion to ask where they were, student took it as 'give it a whirl' and engaged start with his hand still resting on the prop. Instructor had a fat purple fist for a couple of weeks post event, best possible outcome considering he could have easily lost the hand completely.
PS I would like to know if there are any modern types that do have POH shut down methods of simply turning off the key.
Last edited by 43Inches; 9th Dec 2021 at 00:30.
I'm trying to get a FlyEFII electronic fuel ignition and injection system working right now, the only way to shut it down correctly is to remove power to the system. In this case with a key. Interestingly you can shut down just the ignition system which should get the same results and turning the mags off on a legacy engine but this leads to a very rough shutdown since the injectors are still metering fuel into the engine very precisely as the prop slows down. The residual heat in the cylinder ignites the fuel / air mixture at random and everything shakes like the dickens. It sure feels like it could damage something.
Which leads me to Griffster94's question. If you are talking about legacy Lycoming and Continental engines with a mixture cutoff control, the way specified by the manufacturers is to shut down with mixture first, then the key once the engine stops. This minimizes the leftover fuel in the intake and cylinders which is ideal for the reasons listed above. It's not that you're going to damage the engine, it's that you're leaving the engine in a more dangerous state than otherwise possible. Some of the older Continental engines don't have a mixture cutoff control and so the only normal way to shut them down is with the ignition key. I've never heard of those engines being damaged from their normal shutdown procedure.
Which leads me to Griffster94's question. If you are talking about legacy Lycoming and Continental engines with a mixture cutoff control, the way specified by the manufacturers is to shut down with mixture first, then the key once the engine stops. This minimizes the leftover fuel in the intake and cylinders which is ideal for the reasons listed above. It's not that you're going to damage the engine, it's that you're leaving the engine in a more dangerous state than otherwise possible. Some of the older Continental engines don't have a mixture cutoff control and so the only normal way to shut them down is with the ignition key. I've never heard of those engines being damaged from their normal shutdown procedure.
What engine are you talking about, here, ahramin, as shaking like dickens?
Is it a 'legacy engine' - which I take to be a 'standard' injected Lycoming or TCM engine - to which you have fitted a FlyEFII system? Or are you talking about a 'standard' injected Lycoming or TCM engine with 'standard' ignition?
I'm trying to get a FlyEFII electronic fuel ignition and injection system working right now, the only way to shut it down correctly is to remove power to the system. In this case with a key. Interestingly you can shut down just the ignition system which should get the same results and turning the mags off on a legacy engine but this leads to a very rough shutdown since the injectors are still metering fuel into the engine very precisely as the prop slows down. The residual heat in the cylinder ignites the fuel / air mixture at random and everything shakes like the dickens. It sure feels like it could damage something.
What engine are you talking about, here, ahramin, as shaking like dickens?Is it a 'legacy engine' - which I take to be a 'standard' injected Lycoming or TCM engine - to which you have fitted a FlyEFII system? Or are you talking about a 'standard' injected Lycoming or TCM engine with 'standard' ignition?
Interesting...
I'm guessing you didn't try shutting it down with the mag switch when the engine it was 'standard'?
Does the system retain the standard injector manifold (the 'spider' with the injector tube 'legs')? You say 'pumps' plural. What pumps are they?
On a standard injected engine at idle, switching the mags off will usually result in a reduction of RPM that reduces the fuel pressure out of the FCU and a consequent shutting off of the valve in the injector manifold and, therefore, no more go juice to the cylinders. Maybe the pressure out of the new pump/s(?) remains quite high in the FlyEFII system.
I'm guessing you didn't try shutting it down with the mag switch when the engine it was 'standard'?
Does the system retain the standard injector manifold (the 'spider' with the injector tube 'legs')? You say 'pumps' plural. What pumps are they?
On a standard injected engine at idle, switching the mags off will usually result in a reduction of RPM that reduces the fuel pressure out of the FCU and a consequent shutting off of the valve in the injector manifold and, therefore, no more go juice to the cylinders. Maybe the pressure out of the new pump/s(?) remains quite high in the FlyEFII system.
This particular engine was never standard but I've flown other IO-375s with standard fuel injection. As you say, shutting one down with ignition rather than fuel is normally a non-event as the fuel mixture becomes initially way too rich and then way too lean followed by cutoff as the RPM decreases. It's possible to get a combustion event or two during the shutdown but normally everything just winds down peacefully. On this fuel system everything is completely replaced from the tank pickups all the way to the injector ports on the cylinders. Fuel pressure is provided by a primary fuel pump with a backup fuel pump in parallel that kicks in if the power to the primary fails or if the fuel pressure drops below 20 psi. It doesn't matter what the fuel pressure is though, the injectors will only deliver fuel on the intake stroke.
During an ignition only shutdown the fuel system is still working at 100% all the way through the shutdown. As the MAP increases and RPM decreases the system is adjusting for this and metering the fuel accordingly so it's much more likely on any given power stroke for a combustion event to happen. This is why the system is normally shut down with the key to kill everything at once, injectors and ignition.
During an ignition only shutdown the fuel system is still working at 100% all the way through the shutdown. As the MAP increases and RPM decreases the system is adjusting for this and metering the fuel accordingly so it's much more likely on any given power stroke for a combustion event to happen. This is why the system is normally shut down with the key to kill everything at once, injectors and ignition.
Well there's the cause of the engine shaking like dickens:
It actually does matter what the fuel pressure is. There's a reason it's called "idle" cut off. If one of your pumps is pushing fuel at 'high' pressure into that standard TCM FCU at idle, some of it will be getting through the FCU into the manifold and the valve in it will never close to provide that 'clean' shutdown. That, presumably, is why you have to switch the 'whole' FlyEFII system to get a 'clean' shut down.
Fuel pressure is provided by a primary fuel pump with a backup fuel pump in parallel that kicks in if the power to the primary fails or if the fuel pressure drops below 20 psi. It doesn't matter what the fuel pressure is though, the injectors will only deliver fuel on the intake stroke.
During an ignition only shutdown the fuel system is still working at 100% all the way through the shutdown.
During an ignition only shutdown the fuel system is still working at 100% all the way through the shutdown.
Last edited by Lead Balloon; 11th Dec 2021 at 05:09.
Yes Lead Balloon, as stated, that's the cause.
I think we're getting confused about what we're talking about. I thought you were asking about the electronic ignition and fuel injection system that I was referring to, but you keep commenting on my statements in relation to a standard Lycoming or Continental fuel injection system. This is not a standard system. There is no idle cut off. In the system I'm talking about, each cylinder has its own electronic injector that meters fuel into that cylinder based on crank timing, manifold pressure, rpm, throttle position, engine temperature, fuel pressure, fuel trim setting, and exhaust O2 ratio. As long as the fuel pressure is between 20 and 40 psi, the system meters correctly. Fuel pressure is regulated at 35 psi from before start until shutdown, and the injectors will do their thing as long as there is power to them. Once power is removed, no fuel goes into the engine regardless of fuel pressure.
The point was to provide one example of a Lycoming or Continental engine that shuts down with the key rather than the mixture in response to a question in this thread. Another example is a C85 which does not have an idle cutoff in the carburetor.
I think we're getting confused about what we're talking about. I thought you were asking about the electronic ignition and fuel injection system that I was referring to, but you keep commenting on my statements in relation to a standard Lycoming or Continental fuel injection system. This is not a standard system. There is no idle cut off. In the system I'm talking about, each cylinder has its own electronic injector that meters fuel into that cylinder based on crank timing, manifold pressure, rpm, throttle position, engine temperature, fuel pressure, fuel trim setting, and exhaust O2 ratio. As long as the fuel pressure is between 20 and 40 psi, the system meters correctly. Fuel pressure is regulated at 35 psi from before start until shutdown, and the injectors will do their thing as long as there is power to them. Once power is removed, no fuel goes into the engine regardless of fuel pressure.
The point was to provide one example of a Lycoming or Continental engine that shuts down with the key rather than the mixture in response to a question in this thread. Another example is a C85 which does not have an idle cutoff in the carburetor.
Just out of interest, what power loss are we talking here? So if you lose the electrical system in the aircraft does the engine fail, or is it more like larger turbines that have an integrated alternator for engine only systems. The turbine not really requiring the alternator to sustain though if the alternator fails, although you do lose some automated control functions. With a spark and fuel injection related piston that would mean total power loss if your electrics were fried, would make lightning strikes possibly interesting. I've never had great trust in aircraft electrical systems, compared to power plants, like boats everything a plane is exposed to is anti wiring and electronics. And talking of IO-360s, the Arrow engine set-up used to blow/drip oil directly into the alternators reducing their life by about 70%.
Yes Lead Balloon, as stated, that's the cause.
I think we're getting confused about what we're talking about. I thought you were asking about the electronic ignition and fuel injection system that I was referring to, but you keep commenting on my statements in relation to a standard Lycoming or Continental fuel injection system. This is not a standard system. There is no idle cut off. In the system I'm talking about, each cylinder has its own electronic injector that meters fuel into that cylinder based on crank timing, manifold pressure, rpm, throttle position, engine temperature, fuel pressure, fuel trim setting, and exhaust O2 ratio. As long as the fuel pressure is between 20 and 40 psi, the system meters correctly. Fuel pressure is regulated at 35 psi from before start until shutdown, and the injectors will do their thing as long as there is power to them. Once power is removed, no fuel goes into the engine regardless of fuel pressure.
The point was to provide one example of a Lycoming or Continental engine that shuts down with the key rather than the mixture in response to a question in this thread. Another example is a C85 which does not have an idle cutoff in the carburetor.
I think we're getting confused about what we're talking about. I thought you were asking about the electronic ignition and fuel injection system that I was referring to, but you keep commenting on my statements in relation to a standard Lycoming or Continental fuel injection system. This is not a standard system. There is no idle cut off. In the system I'm talking about, each cylinder has its own electronic injector that meters fuel into that cylinder based on crank timing, manifold pressure, rpm, throttle position, engine temperature, fuel pressure, fuel trim setting, and exhaust O2 ratio. As long as the fuel pressure is between 20 and 40 psi, the system meters correctly. Fuel pressure is regulated at 35 psi from before start until shutdown, and the injectors will do their thing as long as there is power to them. Once power is removed, no fuel goes into the engine regardless of fuel pressure.
The point was to provide one example of a Lycoming or Continental engine that shuts down with the key rather than the mixture in response to a question in this thread. Another example is a C85 which does not have an idle cutoff in the carburetor.
Just out of interest, what power loss are we talking here? So if you lose the electrical system in the aircraft does the engine fail, or is it more like larger turbines that have an integrated alternator for engine only systems. The turbine not really requiring the alternator to sustain though if the alternator fails, although you do lose some automated control functions. With a spark and fuel injection related piston that would mean total power loss if your electrics were fried, would make lightning strikes possibly interesting. I've never had great trust in aircraft electrical systems, compared to power plants, like boats everything a plane is exposed to is anti wiring and electronics. And talking of IO-360s, the Arrow engine set-up used to blow/drip oil directly into the alternators reducing their life by about 70%.
On the other hand, this aircraft has a very complex engine and electrical system. The electrical system is powered by two batteries and an alternator. There's a fancy bus manager that should isolate a battery or bus fault and also has an emergency switch to directly connect one battery to the engine bus. The engine system has two independent ECUs, each of which is capable of running the engine. Unfortunately, between electrical system and the engine control system is a single 15A breaker so if that breaker fails, the engine quits with no way to recover it. There are a few additional less probable but still worrying single points of failure. Lightning strikes are not really a concern but nevertheless, trust is low.