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Saville

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Thanks for the input. Everything is on the table at this point.

There were no major problems with the electrical system concerning current draw until after the 8 O2 sensors / heaters were installed.

Until then, normal amp readings were 19 to 24. On all engine runs, taxi tests, and the first few test flights.

After O2 sensor installation, amps were as high as 50.

The aircraft was fully powered on the final flight. All buses powered, essential and main. Even after the crash.

8 O2 sensors with heaters can pull 16 amps. They were wired into the circuit for the ECU. That is a 15 amp breaker.

Do you still have any other device connected to the same breaker as the ECU?

If so, do you intend to keep it that way?
 
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Saville

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At this time, with all 8 O2 sensors and heaters removed, nothing is on the ECU CB, except the MoTeC ECU.
So the G3X is not on the ECU breaker any more? I thought you had several "essentials" on the same CB which included the G3X.

And do you intend that the MoTeC ECU breaker will have nothing else on it?
 

TXFlyGuy

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The ECU and the G3X are on the essential bus. But nothing other the the ECU is on it’s cicuit.
The G3X Touch was never on the ECU cicuit.
 

TFF

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I’m sure if it was insured, it was an insurance total. Easier for insurance to scrap than put a number on fixing a rare homebuilt airplane. The question for owner comes, buy back and fix, or let go?
 

Saville

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The ECU and the G3X are on the essential bus. But nothing other the the ECU is on it’s cicuit.
The G3X Touch was never on the ECU cicuit.

I've found it really difficult to follow your description of your setup. Perhaps I'm just dumb.,

In "Phase One- Safety" post #134 you state:

"This is the essential bus...fuel pumps, ECU, coils, and G3X Touch. Everything to keep the engine running, with engine instruments displayed." And you said you were looking at a second source for power.

Fuel pumps? Coils???

Several of us has stated, repeatedly, that the ECU power should be on it's own circuit breaker. For example, Vigilant1 wrote (in post #164):

"If the wiring to the G3X, the unit itself, or the sensors hooked to it short to ground and can draw enough amperage to pop that breaker that feeds your ECU,, the good news is that you won't need the G3X in order to know your oil pressure or RPM anymore."

and you seem to resist this idea.

But if you resist it that means there were more things on the ECU circuit breaker than just the ECU.

But now you are using the term "circuit" and I have to confess I don't know what you mean by that. Nor what you now mean by "essential bus".
 

TXFlyGuy

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I hired professionals to do all of the wiring.
I can’t show you a diagram, but this is fact.

The ECU is on it’s own CB.
The ECU is powered by the essential bus. During the crash, the essential bus, as well as the main bus, were fully powered. The entire aircraft had electrical power. But, the 15 amp ECU CB tripped.

Essential bus is an airline term, from my 727 days. The only items on it are what is considered essential for flight. Yes, we consider fuel pumps, engine instruments…manifold pressure, rpm, oil temp, fuel quantity, all essential.

I beg your pardon if my explanation has been less than clear.

edit: During the crash flight, all 8 O2 sensors (Bosch) and heaters were on the ECU CB.
 
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gtae07

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8 O2 sensors with heaters can pull 16 amps. They were wired into the circuit for the ECU. That is a 15 amp breaker.
Even everything else aside... did nobody do a basic load analysis?

And eight O2 sensors? Are you running individual fuel trims on each cylinder?
 

wsimpso1

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I've found it really difficult to follow your description of your setup. Perhaps I'm just dumb.,

In "Phase One- Safety" post #134 you state:

"This is the essential bus...fuel pumps, ECU, coils, and G3X Touch. Everything to keep the engine running, with engine instruments displayed." And you said you were looking at a second source for power.

Fuel pumps? Coils???

Several of us has stated, repeatedly, that the ECU power should be on it's own circuit breaker. For example, Vigilant1 wrote (in post #164):

"If the wiring to the G3X, the unit itself, or the sensors hooked to it short to ground and can draw enough amperage to pop that breaker that feeds your ECU,, the good news is that you won't need the G3X in order to know your oil pressure or RPM anymore."

and you seem to resist this idea.

But if you resist it that means there were more things on the ECU circuit breaker than just the ECU.

But now you are using the term "circuit" and I have to confess I don't know what you mean by that. Nor what you now mean by "essential bus".
Careful here. Some knowledge might be in order before assuming more bad things about TEXFlyGuy's bird.

First, The Essential Bus does not preclude powering each of the "must have" items with their own circuit protection. Each item can have its own circuit protection.

The concept of the essential bus is usually for managing an alternator loss - Put a bus bar and fuses or circuit breakers feeding the things that must remain powered (essential) while everything else (non-essential) is powered from other buses that you turn off when the alternator packs up. Also useful when you have two alternators, but one is small and so can only power the essential stuff. Alt packs it up, you turn off the main, lose the stuff you do not absolutely need along with the current draw of the main contactor, fly on to an airport on your battery or standby alternator, then when the airport shows up, pull on the main, get lights or gear or whatever... None of this precludes separate fuses/breakers for each piece of essential hardware.

The concept evolved from Emergency Bus to Essential Bus and Endurance Bus. Then when we all got friendly with using two alternators and automated power cascades, it even evolved into simply a Main and an Always Hot Bus. The Always Hot Bus is connected directly to the battery, has the really essential stuff, (ECU, ignition coils, injectors, sensors, regulators, maybe some Nav and Com), and each item is circuit protected and switched. Some of us have gone so far as to use redundant switches for stuff powered off the Always Hot Bus. Everything else comes up when the main breaker is switched on, coming off the Main Bus. You might even have an Engine Bus that is always hot.

The alternative is to take a task saturated pilot and put them in the position of figuring out what to turn off and what to leave on. Better to allow one switch throw to reduce power use to a pre-determined level, slow the power use from the battery, and allow the pilot to figure out how to get to an airport. If the emergency persists, and all power must go away, you turn off the rest and do the best forced landing you can.

IIRC, there were other folks (not the OP) who suggested other stuff was on the CB for the ECU, and yes I too pushed back against that notion.

TEXFlyGuy has plenty on his plate without sucking up other topics.

Billski
 

Saville

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Careful here. Some knowledge might be in order before assuming more bad things about TEXFlyGuy's bird.

My whole, entire point is that I'm trying to NOT assume anything. Instead, I am asking questions and trying to put historical and present comments together. But the answers confuse me. perhaps I'm the only one confused.
 

wsimpso1

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Even everything else aside... did nobody do a basic load analysis?
Not everyone is a follower of Brother Bob Nuckolls...

And eight O2 sensors? Are you running individual fuel trims on each cylinder?
It is a V8. Each cylinder is likely to have different optimal fuel flows. I know that cars and trucks use only one HEGO per bank and that is probably be OK where an exhaust manifold mixes the feed gases together and dumps them on a catalyst. Doesn't this beast have short pipes?

The differences in induction, combustion chamber volume, and exhaust can be significant. In my vibe work at two car companies I have seen different signatures on all 8 cylinders. Induction and exhaust track lengths vary, combustion chambers vary, and combustion chambers vary along the head. It is common in V engines that use the same head part number for both banks to see the same pattern of most-mid-least in both banks and to see differences between banks. If I can see that in the vibe input, you gotta know those cylinders are breathing differently. So, maybe it will benefit the bird to tune all eight cylinders separately.

Billski
 

TXFlyGuy

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Not everyone is a follower of Brother Bob Nuckolls...


It is a V8. Each cylinder is likely to have different optimal fuel flows. I know that cars and trucks use only one HEGO per bank and that is probably be OK where an exhaust manifold mixes the feed gases together and dumps them on a catalyst. Doesn't this beast have short pipes?

The differences in induction, combustion chamber volume, and exhaust can be significant. In my vibe work at two car companies I have seen different signatures on all 8 cylinders. Induction and exhaust track lengths vary, combustion chambers vary, and combustion chambers vary along the head. It is common in V engines that use the same head part number for both banks to see the same pattern of most-mid-least in both banks and to see differences between banks. If I can see that in the vibe input, you gotta know those cylinders are breathing differently. So, maybe it will benefit the bird to tune all eight cylinders separately.

Billski
P1050789.JPG

P1050786.JPG
 

TerryM76

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What is the purpose for the "8 heaters"? I'm just trying to learn more about this installation and haven't encountered electric heaters except for engine preheater installations.

Thanks.

Terry
 

TFF

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The quality is not the issue here. It’s all tops. But this is about guaranteeing nothing but the ecu should be allowed to kill that circuit. ECU, alternator, battery, wires, it’s CBs, that’s it. Any test items or anything else needed for flight is on its separate alternator, battery and buss system. Connecting the buss for emergency instruments and gear to the engine will be called emergency only. Same with the engine the other direction. It’s not that it can’t be made to work together, but this is a $100,000 overload mistake in wiring an something not going for a world record attempt where failure is part of the game. Can it happen segregated, sure. Bad days can just happen. But that’s where you want to be. If you did everything and bad luck was going to win, that’s all it is. No what ifs. Is installation like this overboard? Yes and it is proving it’s how deep you need to protect something. 8 O2 sensors is an anomaly, but what is being done with regular anomalies. The engine should only quit with its anomalies, not anything else. Overloads from gear or flaps or aircraft systems or test equipment should never kill the engine. It shouldn’t know that stuff exists. Pain in the but to have two alternators. Pain to have two equal batteries, but not this kind of pain. The California crash was engine stopping because it took down all the electrical with engine attached. No time for the switch over. Crunch.

O2 sensors have heaters in them.
 

Mad MAC

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What does the current, electrical load analysis look like?

Its been a while since I done one on a GA aircraft but the last one (15 years ago) on a bog standard GA 2 seat fixed gear trainer with a simple engine and a (very) full instument panel would pretty much max out the full 60 amp if you did circuits. The Avonics & ligths have improved endlessly in that period but you got a lot of other power hunger systems.
 

Kyle Boatright

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What does the current, electrical load analysis look like?

Its been a while since I done one on a GA aircraft but the last one (15 years ago) on a bog standard GA 2 seat fixed gear trainer with a simple engine and a (very) full instument panel would pretty much max out the full 60 amp if you did circuits. The Avonics & ligths have improved endlessly in that period but you got a lot of other power hunger systems.
My Rv-10 has an average load of under 20 amps with all the always on stuff - a G3X, autopilot, and the strobes and nav lights on. The flap motor and fuel pump are intermittent loads. Even with the landing lights and heated pitot on, the load is under 60 amps with all of the intermittent stuff on.
 

TXFlyGuy

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To sum this up, my electrical system has triple redundancy. Dual bus, dual battery system. The essential bus will always be powered. Worst case is at the end of 90 minutes with an alternator failure, the main battery is drained, and the back up battery is nearly drained. But a landing will have been made prior to the 90 minute time limit.

The essential bus powers the Engine Control Unit. The ECU has a dedicated circuit with a CB. Nothing else (nothing!) is on that circuit except the ECU.

A new 60 amp alternator has been purchased. I will have my avionics technician go over everything prior to the first flight after the repairs are made.
 
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