Emergency Smoke System Shut Off. Ideas considered.

[RV8iator]

Originally Posted by C-FAH Q

Would one switch control both fuel and smoke oil pumps?
Some more information on device details and installation tips would be good.

The switch is wired into the ground wires of both pumps so it shuts off both immediately if it is tripped.

[phobos_49]

What a Thread. I have mine on the Throttle. Not hard to keep on and not hard to let go of.

[Kahuna]

Originally Posted by C-FAH Q

Would one switch control both fuel and smoke oil pumps?
Some more information on device details and installation tips would be good.

Gary good questions.
It could have been placed on either the + or - side of the circuit. And we have installed them both ways. In my case, I have relays on both the fuel and smoke pumps. It was a simple matter in my case to control the ground side of the relay circuit coil with light weight 22ga wire to the inertia switch. But it matters not which side of the circuit you put the device in since its simply a mechanical switch. Manufacturer says the switch is good for 10amps at 12v. Our smoke and fuel pumps combined draw in the 7amps range steady state so the + side is just fine as well. I ran a 15amp light on it for a couple days both + and - sides of the circuit and it was not visibly damaged nor did it stop functioning as designed.

It can be mounted any which a way on anything, although the manufacturer says on a firm, rigid surface. Mine is on my baggage wall. Any convenient place is fine behins the FW.

Here is what it looks like.

2 mounting ears, 2 wires. Put in it line with any number of devices. Has a resetable button for inadvertant trips. I smashed my 8 into landings as hard as I dared and was never able to trip it. You can play with it in your hand and trip and reset it. You will be surprised how little impact in yout hand trips it but I could not trip it with hard landings nor +6 -2 g's on my plane.

Another neat thing is you do not have to hook it to anything to try it. When you push the button in you can feel if it is resetting or not. You can also just check continuity across the wires to test as well.
So you can just mount it to something, go play and try and trip it, and return to test it.

Some of our pilots mounted it in a place under/behind the panel where they could reach it in the case of an inadvertent trip. I did not. I figure if i trip it, I probably have bigger issues to worry about.

Feel free to ask any other questions. Good discussion.

[B25Flyer]

Kahuna,

I have a strong interest in this, for two reasons, the first is below, but my new interest is that I am now the chairman of the ICAS Safety Committee.

When I got the call from Kyle and he told me that Amanda burned up in a smoke oil fire, I almost threw up... I was sitting at my desk looking at an ELT activation switch that I bought from a company Inertia Switch company.
http://www.inertiaswitch.com/inertia.html

Steve Oliver and I have discussed this for years so several years ago I bought two of these switches from them and tried to find someone to build a small box that could be easily retrofitted to accomplish this purpose.

These switches are open and close when they sense an impact and I envisioned, and roughed out a crowbar circuit that could be installed in the Master solenoid circuit, (either hot or ground) that would use a C/B switch as a master switch and trip that switch when an impact occurred taking out the entire system.

The buggabo in my circuit is, depending on the system, if the engine continued to run, the alternator could keep the buss hot even when the master C/B switch was tripped.

WE DESPERATELY need to find a manufacturer that is trusted in the Airshow community to build these kits. I went to Bill Bainbridge (before Amanda's accident) and asked him to build them but he said the market was too small and he was too busy. I have neither the facilities or the credibility to build the kits, but I will support and sell them for who ever will do it.

Tailwinds,
Doug Rozendaal
Chairman ICAS Safety Committee

[Kahuna]

Doug,
What is it about this inertia switch solution that you feel does not address the problem?

This switch could easily be placed in-line of the master solenoid circuit and would kill the master. I would not be comfortable with this until it receives more aviation field testing. In our world of electrically dependent systems (my dual EI as an example), it would take additional consideration for me to install it in this way.

Worse case now is, if the switch fails, trips, or otherwise goes TU, the worse I loose is electric fuel pump and smoke. With the mechanical fuel pump, Im comfortable with this risk.

This inertia switch is a very good first step unless or until another alternative is available. We wanted to take action now. Do something good before our memories fail us.

Oh and congrats on the new role. Well deserved.

[N941WR]

Kahuna and Doug,

My only thought on the inertia switch is that you could have a catastrophic engine failure and fire and your smoke oil pump will keep on pumping, feeding the fire.

The idea of turning off the smoke system (and electric fuel pump) based on the oil pressure seems to be the best, in my humble, no airshow experience, opinion.

[B25Flyer]

Originally Posted by Kahuna

Doug,
What is it about this inertia switch solution that you feel does not address the problem?

The +10/-6 guys think they can trip the automotive inertia switch it in flight. The ELT switch only senses fwd impact and it is really hard to stop an airplane quickly without hitting something. And the accidents that happen tail first, or in the y axis are moot because they aren't survivable anyway.

For the RV crowd, I think your solution is great. I recommend killing the entire electrical system including the big fat starter wire in front of the firewall that is often the ignition source....

Tailwinds,
Doug Rozendaal

[vlittle]

Originally Posted by N941WR

Kahuna and Doug,

My only thought on the inertia switch is that you could have a catastrophic engine failure and fire and your smoke oil pump will keep on pumping, feeding the fire.

The idea of turning off the smoke system (and electric fuel pump) based on the oil pressure seems to be the best, in my humble, no airshow experience, opinion.

...So an engine failure in flight, leads to low oil pressure, which turns off the fuel pump, so you can't do a re-start. It's the law of unintended consequences.

Whatevery system is employed needs a bypass or manual mode. In my opinion, automatic control of the critical aircraft systems leads to stall/spin accidents from 35,000 feet into the Carribean ocean.

V

[Flying EMT]

The full sized ford cars have a inertia switch usually located in the left trunk wall that is wired into the car's fuel pump to shut it off in a crash from any direction. I'll check into one tuesday at work to see if it is wired heavy enough for a smoke pump. If not heavey enough for the pump directly, you could wire a rely into it. FWIW. - Ben

[C-FAH Q]

That answered my questions perfectly.
Thx

Originally Posted by Kahuna

Gary good questions.
It could have been placed on either the + or - side of the circuit. And we have installed them both ways. In my case, I have relays on both the fuel and smoke pumps. It was a simple matter in my case to control the ground side of the relay circuit coil with light weight 22ga wire to the inertia switch. But it matters not which side of the circuit you put the device in since its simply a mechanical switch. Manufacturer says the switch is good for 10amps at 12v. Our smoke and fuel pumps combined draw in the 7amps range steady state so the + side is just fine as well. I ran a 15amp light on it for a couple days both + and - sides of the circuit and it was not visibly damaged nor did it stop functioning as designed.

It can be mounted any which a way on anything, although the manufacturer says on a firm, rigid surface. Mine is on my baggage wall. Any convenient place is fine behins the FW.

Here is what it looks like.

2 mounting ears, 2 wires. Put in it line with any number of devices. Has a resetable button for inadvertant trips. I smashed my 8 into landings as hard as I dared and was never able to trip it. You can play with it in your hand and trip and reset it. You will be surprised how little impact in yout hand trips it but I could not trip it with hard landings nor +6 -2 g's on my plane.

Another neat thing is you do not have to hook it to anything to try it. When you push the button in you can feel if it is resetting or not. You can also just check continuity across the wires to test as well.
So you can just mount it to something, go play and try and trip it, and return to test it.

Some of our pilots mounted it in a place under/behind the panel where they could reach it in the case of an inadvertent trip. I did not. I figure if i trip it, I probably have bigger issues to worry about.

Feel free to ask any other questions. Good discussion.