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Emergency Smoke System Shut Off. Ideas considered.

Kahuna

Kahuna

Moderatoring
The RV community has many smoke systems installed. Below is an exceprt from Air Shows Magazine. Having made a dead stick landing in my RV during an air show with a smoke system I could not shut off, this work is looking me square in the eye. Feel free to banter your ideas here. We are looking for the best solution. The ACE heading this effort is Georgias own Buck Roetman.
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41773_1656786786_3610_n.jpg

Recent accidents, like the March crash that inflicted serious burn
injuries on Amanda Franklin, have strengthened resolve among
ICAS members to create an easily-retrofitted automatic smoke oil
pump shut-off for piston-powered airplanes.
“The oil is a lightweight, paraffin-based mineral oil that is vaporized
in an environment with little oxygen,” said aerobatic performer
Buck Roetman. He says smoke oil is most dangerous when
an engine fails. The already hot exhaust continues to vaporize
smoke oil during a crash.
“It’s an environment that is very conducive to flash fires,” said
Roetman. “The electric pump continues to pump, and it just feeds
the fire.”
Roetman is spearheading an ICAS effort to design an automatic
shut-off switch for smoke pumps. When the oil pressure in an airplane’s
engine drops, like during an engine failure, an automatic
switch will sense the reduced oil pressure and shut off a relay that
runs to the smoke pump.
“It should be easy to install,” said Roetman, adding that the retrofit
will work on any airplane with an electric smoke pump. “I don’t
see it being more than a couple hours [of work] and it will cost
about $50.”
Roetman knows the real dangers of smoke oil. His engine failed
with the smoke on during a flat spin. He hit the starter after the
smoke pump ran for just a few seconds. “The resulting flash fire
shrunk the tapes on the bottom of the airplane and I could feel
heat on the back of my legs through a nomex suit,” said Roetman.
“If we don’t do this cheaply and simply, it won’t get done,” said
Roetman. “This is about saving our friends.”
 
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I have no oil switch

One of the challenges I face with a modern engine management system is that I do not have an oil pressure switch, only an oil pressure sensor. I let my engine monitor handle alerting me if my oil pressure gets too low.

Adding an oil pressure switch is no problem and cheap, but it has to be weighed against the risk of adding another line and device that has a potential for failure that could result in the loss of oil pressure. Ive noodled on how to resolve this problem in other ways and I have not come up with a simple, effective, near zero additional risk way to solve the problem.
 
At the present time, the issue is being worked by at least one company.

http://www.smokingairplanes.com/doc...CEBULLITEN-11-002-USEOFONCONTINUOUSSWITCH.doc

The "G" switch from an ELT comes to mind. Your oil pressure switch through a relay would work but there is always the possibility of the contacts wielding together from the motor current surge. Will have that issue with anything that stops the motor current flow.
 
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Oil pressure switch

I don't have a smoke system, but I do have an oil pressure switch. Its mounted in to one position of a Van's 3-position VA-168 sender mount. The oil pressure sender is adjacent on the same mount. There is one oil line from the engine, and a short (a few inches) U-tube from the pressure send to the pressure switch.

Nothing is ever failure-proof, but this is about as simple and durable as you can get a I think.
 
Master switch?

Mike, is the oil shut off when the master switch for the airplane is off? If so, make that part of your forced landing procedure. After all, you don't have an automatic off for the fuel!

Since I had that burned fuel line on the hot exhaust in my -10, I have begun drilling my head with "Fuel off..fuel off" ever since and everything electrical as well.

Best,
 
Pierre, Yes you are correct. This would be true in a normal emergency situation if there is such a thing.

Unfortunately in many air show environments, and in many other situations, there is not time for this with hands full, particularly with flight control problems, low altitudes, spectators, other planes near you, and other priorities keeping the pilot busy. This is the reason for the safety feature needs on a forced landing where the pilot has his hands full. My incident, Kyle Franklins, The recent Mustang mid air(was not running smoke but could have been), and other examples, drives the need for this.
 
My 2 cnets

This might be overly simple, but what about having the smoke pump on a momentary switch that you have to hold down. If something happens, it should be reflex to turn loose of the button?
 
panhandler1956 said:
This might be overly simple, but what about having the smoke pump on a momentary switch that you have to hold down. If something happens, it should be reflex to turn loose of the button?
Click to expand...

Yes this is one option for the pilot just flying by with smoke. It is not a feasible option for anyone that needs to fly their plane precisely while moving the stick and throttle and leaving their smoke on while doing it. If you have seen the large osh formations, or Team RV, or other performers, or other examples, there is just no way to finesse your plane the way it needs to be finessed while holding a button.
 
Kahuna said:
Yes this is one option for the pilot just flying by with smoke. It is not a feasible option for anyone that needs to fly their plane precisely while moving the stick and throttle and leaving their smoke on while doing it. If you have seen the large osh formations, or Team RV, or other performers, or other examples, there is just no way to finesse your plane the way it needs to be finessed while holding a button.
Click to expand...

That makes sense.
 
Kahuna,
What is the amp draw of the smoke oil pump? We are all familiar with the oil pressure switches that are commonly used to run a Hobbs meter. But I question if they could take the current of the pump.
Maybe one of our high tech guys could design you a voice activated system like todays automobiles. I could just see it now..."Hal! I said "smoke off" not radio on!"
The other question is; if your engine fails for whatever reason, unless you have dumped all your oil, or the engine stops turning, you are still going to have oil pressure. So, would an oil pressure safety switch really be the best avenue?
 
jetjok said:
Kahuna,
What is the amp draw of the smoke oil pump? We are all familiar with the oil pressure switches that are commonly used to run a Hobbs meter. But I question if they could take the current of the pump.
Maybe one of our high tech guys could design you a voice activated system like todays automobiles. I could just see it now..."Hal! I said "smoke off" not radio on!"
The other question is; if your engine fails for whatever reason, unless you have dumped all your oil, or the engine stops turning, you are still going to have oil pressure. So, would an oil pressure safety switch really be the best avenue?
Click to expand...

Mark,
The amp draw is not of particular concern since a simple relay can be used , and often is, to deal with that. Amp draw startup is in the 5 amp range, 3amp continuous.

The windmilling prop will likely keep oil pressure numbers and switch open until touchdown or impact as the case may be. We accept that. But when stopped, we want the smoke oil to stop and not fuel any fire that may arise.

The solution would need to be simple, effective, idiot proof, and cheap for adoption to take place.
 
Can this be used/modified?

Fuel Pump Shut-Off Switch (Low Oil Pressure)

A recommended safety feature when using an electric fuel pump, this switch automatically cuts power to the pump when oil pressure is lost to help reduce the fire hazard in case of an accident. Similar switches are installed in some production vehicles as original equipment. Factory setting is 12psi. Installs in a 1/8 NPT thread.
 
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xavierm said:
Fuel Pump Shut-Off Switch (Low Oil Pressure)

A recommended safety feature when using an electric fuel pump, this switch automatically cuts power to the pump when oil pressure is lost to help reduce the fire hazard in case of an accident. Similar switches are installed in some production vehicles as original equipment. Factory setting is 12psi. Installs in a 1/8 NPT thread.
Click to expand...

any oil pressure SWITCH will work fine for cutting smoke oil off. See previous posts as to why this is one solution but we are looking for others for reasons discussed.
And cutting off the electric fuel pump when there is no oil pressure would not work for obvious reasons.
 
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Just thinking here: What about a two switch system; The primary power is activated by hand pressure on the throttle. During smoke system operation you would have to squeeze the throttle handle to activate the circuit to the smoke system, which would then operate as normal. Release the pressure and the system stops.
An alternative would be a smoke system cut off switch that would not allow smoke if the throttle was in the idle position. I realize that there are times when idle is the power setting during aerobatics but there might be a variation of this type of system that would work.
 
EGT cutoff

an EGT cut-off switch. Not as simple as the oil switch as you might have to wire this up yourself but not too hard either.

When the engine stops running the one thing you can be sure of is EGT drops very quickly while oil pressure will be a function of prop RPM.

Put a second egt probe in the exhaust stack(s) with smoke nozzles and wire to an op-amp (though some conditioning). You set the temp at which a normally open relay closes allowing smoke to function. If the temp goes below this value the relay opens and smoke is off. This also helps if ever a cyl goes bad preventing spraying oil all over the place. Additionally you can set the value high enough to ensure the smoke only works when the temp is high enough to burn it properly (higher power). Even at idle, EGTs are in the 800-900's so set the temp at 700 and it'll work.

You'll need the mV/deg data for the probe to know where to set the op-amps differential input and some parts to create a bridge for the probe.

Not as simple as the oil switch but believe it would function better.
 
Simple

If voltage is less than 13.5V (adjust for your electrical system), turn the smoke oil pump off. Obviously, if the alternator isn't working then something is very wrong. This would be a very simple circuit for an electrical engineer. There are probably some usable examples out there somewhere...

This circuit could go directly in-line with the smoke oil pump and would require no additional wiring of any kind.

Of course, this assumes you have an alternator. Are there any aircraft out there with a smoke system but no alternator? Seems unlikely, but...

my $0.02

On second thought... The alternator would likely still be generating power if the prop is windmilling... Maybe not a complete solution, but at least would stop the oil pump at the crash site.
 
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RV8R999 said:
an EGT cut-off switch. Not as simple as the oil switch as you might have to wire this up yourself but not too hard either.

When the engine stops running the one thing you can be sure of is EGT drops very quickly while oil pressure will be a function of prop RPM.

Put a second egt probe in the exhaust stack(s) with smoke nozzles and wire to an op-amp (though some conditioning). You set the temp at which a normally open relay closes allowing smoke to function. If the temp goes below this value the relay opens and smoke is off. This also helps if ever a cyl goes bad preventing spraying oil all over the place. Additionally you can set the value high enough to ensure the smoke only works when the temp is high enough to burn it properly (higher power). Even at idle, EGTs are in the 800-900's so set the temp at 700 and it'll work.

You'll need the mV/deg data for the probe to know where to set the op-amps differential input and some parts to create a bridge for the probe.

Not as simple as the oil switch but believe it would function better.
Click to expand...

OK Ken. WHen you gonna build us a prototype?
 
no need:
http://www.thesensorconnection.net/...ite-pmd-series-mini-meter-pyrometer-peak-hold

wire the relay contact in series with your smoke oil motor and the set the high alarm at about idle EGT. When the engine is on the relay is tripped due to the high set point alarm and you can turn smoke on. Engine quits, EGT falls below the limit and relay is open shutting off the alarm.

$58 buck plus an EGT probe. You don't really need to see the display so mount it out of the way some place.
 
Another Option

Kahuna, what about using a proximity switch or photo eye on the flywheel? Diesel engines use this as a "zero speed" switch to detect engine stoppage. Lots of options are out there for these kinds of switches, some not too expensive. Lastly, I would add the relay as a secondary cutoff for power to the electric pump, that is, in addition to whatever controls currently exist for the pump.

For what its worth....

Michael
 
Why not simply insure the smoke switch is large and easily reached. Then drill into your head immediate action steps for engine failure with smoke off being the first step. Perhaps the switch should be next to the mixture control. It seems to me the bigger problem here was a lack of knowledge of what oil smoke can do if the engine fails. Now that we know that we change the procedures. Tapping into oil lines ect.. to prevent the problem seems to open up engine failure paths that could exceed the problem your trying to correct.

George
 
sailvi767 said:
Why not simply insure the smoke switch is large and easily reached. Then drill into your head immediate action steps for engine failure with smoke off being the first step. Perhaps the switch should be next to the mixture control. It seems to me the bigger problem here was a lack of knowledge of what oil smoke can do if the engine fails. Now that we know that we change the procedures. Tapping into oil lines ect.. to prevent the problem seems to open up engine failure paths that could exceed the problem your trying to correct.

George
Click to expand...

It's not that simple. Doing aerobatics close to the ground leaves little or no time to go through "immediate action steps" if something goes terribly wrong. If I had a flight control failure at 100 feet AGL I would devote 100% of my effort to flying the airplane. If the large red smoke switch was right in front of my face I would ignore it and fly my airplane as far into the crash as possible. We need something that works without pilot input.
 
Lionclaw said:
Will an inertia-activated fuel shutoff switch work?

http://www.smartracingproducts.com/pdfdocs/935100_fuelshutoff.pdf
Click to expand...

Boy I dont see why not. FOr not only the smoke oil, but for an electric fuel pump which we always use at low levels.
I like this simple idea a lot.
Im gonna play with this idea.
At ~$65, its not an expensive solution. And I sure like that non-intrusive method of killing the pump without adding any more oil switch/lines etc.
Many thanks for this great lead. I had no idea these existed.
 
Kahuna what tou want to do can be easily accomplished with a few resistors, a comparitor, and a mosfet. Total cost, about $3.00. You would just hook this circuit right into your oil pressure sensor circuit and it would have no impact on your efis. Need to know the current draw of the pump and the voltage of the pressure sensor at zero oil pressure. Call me I'm at OSH.
 
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As a result of field testing and various bantering of ideas, we have settled on the inertia cut off switch. Thanks to the folks here on the forum for your help in improving safety for all of us.
Press release here.

Pasted text below.

Collaboration Yields Solution to Reduce Risk of Post-Impact Fires for Air Show Performers
(Atlanta, GA) January 12, 2012 ? Aerobatic pilots Buck Roetman of Wild Horse Aviation, and Mike Stewart, Flight Lead for Team RV, announce an important safety solution for professional air show pilots to reduce the risk of a post-impact fire: an inertia activated shut-off switch installed in the ground wire to fuel and smoke oil pumps. Roetman said the easy installation of this inexpensive switch is an "elegant and simple solution that every performer in the air show industry should consider."

Roetman and Stewart sought this solution in response to the forced landing last March of Kyle and Amanda Franklin in which the smoke oil pump fueled a fire that caused fatal burns to Amanda. In the immediate aftermath of the accident, Roetman, who is an International Council of Air Shows (ICAS) ACE (Aerobatic Competency Evaluation) pilot, and ICAS President John Cudahy informally discussed the need to prevent post-impact fires in cases where fuel tanks are not ruptured.

Initial discussions among several pilots included the merits of various shut-off switches such as a GPS switch, EGT switch, and oil pressure switch. Ultimately, Stewart found and suggested the use of the inertia switch which is used in auto racing and acts like a circuit breaker, but is tripped by high g's (10g or higher) associated with impact.

According to Jim Hillyer at Pegasus Auto Racing Supplies, a top supplier of the switch, the product has been used successfully for years on IndyCars and on high-end production cars with fuel injection systems that engage high pressure fuel pumps.

Concerned about inadvertently tripping the switch, Stewart and Roetman installed the device on their aircraft ? Stewart's RV-Super 8 and Roetman's modified Christen Eagle ? and tested high g maneuvers as well as hard landings. The switch did not activate under a +8 g load or -5 g load.

Kyle Franklin is installing this equipment in all of his aircraft, and urges every air show and competition pilot to add this or something similar. The g-meter in his Waco stopped at 11g during his hard landing. "This little switch could save you and your loved ones a lifetime of pain and grief. I truly feel if I had this switch on March 12 my beautiful wife Amanda would still be here," said Franklin.

Stewart reported that all 12 pilots on Team RV have installed the light weight switch as part of pre-season aircraft maintenance procedures. "Air show performers keep safety at the forefront always, and when accidents do happen, they happen to friends in this tight community and not simply to 'someone else.' As a result we take it to task to learn as much as possible from incidents and to find ways to improve safety where possible," said Stewart.

Wild Horse Aviation specializes in aircraft acquisition, maintenance, fabrication and export.
Team RV is the world's largest precision formation and formation aerobatics air show team.
 
Why not simply run the hose through a simple ball valve or fuel type shut off valve and make it part of your emergency checklist.
 
Great solution

Would one switch control both fuel and smoke oil pumps?
Some more information on device details and installation tips would be good.
 
131RB said:
Why not simply run the hose through a simple ball valve or fuel type shut off valve and make it part of your emergency checklist.
Click to expand...

Kahuna wrote: "As a result of field testing and various bantering of ideas, we have settled on the inertia cut off switch."
That's good enough for me.

But to answer your question I think the main reason is that in a low level problem there is no time to complete the checklist.

Mark
 
131RB said:
Why not simply run the hose through a simple ball valve or fuel type shut off valve and make it part of your emergency checklist.
Click to expand...

Because in instances that this is designed for there is no such thing as " going through an emergency checklist".....when you literally have mere seconds between flying and then being on fire post crash, checklists aren't an option. We spent a lot of time discussing this and just didn't have the time to get it done, so I'm glad someone picked up the ball and completed it. This is meant as one of those last ditch emergency life saving devices that hopefully never is activated, but if it is may make the difference between life and death. In the world that this is intended, sometimes an event/incident has happened before the pilot even knows there is something wrong.

Also, this just isn't physically possible given the way many airshow airplanes are plumbed....

This isn't necessarily a device for the every man's airplane and re-ivention of the wheel isn't needed here if you intend to install in your aircraft. Believe me, there have been many, many discussions with many smart folks on this over the past year with almost every conceivable iteration looked at in detail from every angle. I am of the opinion that this is probably the best all around result without building a space shuttle level device. This is an especially touchy subject and personally emotional for many of the folks involved in it given the reasoning for it's implementation.

My 2 cents as usual.

Stein
 
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Yes it does

C-FAH Q said:
Would one switch control both fuel and smoke oil pumps?
Some more information on device details and installation tips would be good.
Click to expand...

The switch is wired into the ground wires of both pumps so it shuts off both immediately if it is tripped.
 
C-FAH Q said:
Would one switch control both fuel and smoke oil pumps?
Some more information on device details and installation tips would be good.
Click to expand...

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.
1108.JPG


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.
 
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
 
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.
 
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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.
 
Kahuna said:
Doug,
What is it about this inertia switch solution that you feel does not address the problem?
Click to expand...

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
 
N941WR said:
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.
Click to expand...

...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
 
inertia switch

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
 
Thanks

That answered my questions perfectly.
Thx



Kahuna said:
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.
1108.JPG


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.
Click to expand...
 
B25Flyer said:
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
Click to expand...

This did not trip this year on installed high G air show planes this year, other than one did trip on impact as designed. I still say this will work for all and is dirt simple and dirt cheap and is an install and forget device.
 
All pumps and ignition sources

We had a terrible accident involving smoke oil but why not view this directly as an electrical safety issue and trigger the master relay? Inadvertent trigger is not a big issue if an E-bus is part of the original design and it shuts down all possible sources of ignition and fluid pumps.
 
Yes I agree. But we wanted to take baby steps with this in our planes and did not want inadvertent trips. Now that we have a full year of solid data, I agree, in the master circuit it should go.
 
jdeas said:
We had a terrible accident involving smoke oil but why not view this directly as an electrical safety issue and trigger the master relay? Inadvertent trigger is not a big issue if an E-bus is part of the original design and it shuts down all possible sources of ignition and fluid pumps.
Click to expand...
Second this point (or taking out the master contactor)! Seems like a significant gain for a very small risk of inadverntent activation. Or if you're one of these all-electric types (dual elect ign, dual elect fuel pump...), install two in parallel.
 
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