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Engine compartment fire extinguisher

170 driver

Well Known Member
With all the talk about fires, I was wondering if anyone has an extinguisher that can be discharged into the cowling while in flight like jets and helicopters do? This seems like a nice safety option if the price is reasonable. I have made my interest in this type of system known to a major manufacturer of these systems and told them there are many of us who may be interested if the price is reasonable. Since this is a non certified experimental market, the cost should be reasonable according to my contact. They are looking into it now.
 
Fire warning

What I was thinking of is a warning system. I have an extra OAT probe and I thought a simple temperature probe in the engine compartment with an alarm set at something other than what normal compartment temperate would be. I have not pursued this since I am still trying to finish the build! This idea would however be fairly low cost to implement. My thinking is putting the probe low in the center of the firewall since all air goes down this way and so if a fire started up high the overall temperature at the exit would rise. A fire loop system would be idea as well but I have not seen one for light airplanes.

Food for thought

Cheers
 
Safecraft

I'm going to put the Safecraft AS5 in my new 7. It is only about 5 lbs. Whether it is 100% effective or not it has to be better than a hand held extinguisher in the cabin when the fire is under the hood!!!

The plan, 2 nozzles in the engine compartment, 1 in the cabin. Also, a couple of yet to be determined fire sensors in the engine compartment.

Here's the Spruce link.http://www.aircraftspruce.com/search/search.php?query=safecraft+as5&searchsubmit=Search&search=1

More specific info at Safecraft.com
 
Elements of fire

Fires require three things, remove any one of them and the fire goes out. Fuel, ignition and oxygen.

All fire extinguishers do is cut the supply of oxygen to the fire. Once the extinguishing agent is used up, the supply of oxygen returns, and the fire potentially re-ignites

The first and most important step is to turn off the supply of gasoline forward of the firewall. With no gasoline, the most flamable substance is now removed.
Now turn off the mags/ei and the electrical system. That will eliminate most sources of ignition, and hopefully prevent re-ignition.
Any remaining or self sustaining fire [burning wires, oil, etc.] can potentially be put out by an extinguishing agent.

It's a great idea, and if the right system is available, I would add one when the time comes. But it's not a one step solution to solve all problems, just another step and added level of protection.
 
There has been alot of research on chemicals since Halon came out,,,there are several other types either available or soon to be available,,,some sound promising for a high airflow environment like inside the cowl. Like a liquid or vaporized powder that coats everything...possibly could put a nozzle or two in the ram air intake area on top of the engine and one behind the acessory case and one under the carb area...
Just some thoughts and some ideas.
 
FWF-fire nozzles

Back in the race car days, we had a fire supression system that discharged both in the cabinn and under the hood (cowl). The cabin system was MANDATORY. I dont know about aircraft, but I do know the the NASCAR supression systems do work.
Maybe its some to look into.
Tom
 
Halon does a fine job of evacuating the oxygen from an area,,,probably not a good thing in an aircraft cabin at altitude,,It may overcome the pilot and then there is a passed out pilot in a plane on fire and some people have said that it is not all that effective in the cowl with a high airflow, it disburses too quickly I suppose...I guess there is no magic bullet just yet,,,but the research is still ongoing I'm sure.
 
What I was thinking of is a warning system. I have an extra OAT probe and I thought a simple temperature probe in the engine compartment with an alarm set at something other than what normal compartment temperate would be.

Would an OAT probe be able to handle those temperatures? I know dynon has room for extra thermocouples, and you can configure those to do what you want, and alarm at temperatures you want.
 
I am installing thermal cutoff fusible links rated at 262F

around my engine compartment in various places...near fuel pump, fuel servo, spider, starter, alternator, filter air box, oil cooler etc. Similiar device used also in sprinkler heads, bank vaults(for the guys that like to use their oxy/acetylene torch), air duct dampers in commercial buildings to cutoff airflow.

I do hvac for a living and have seen these save many homes from burning down. They can be purchased for around $3.00/ea or less depending on qty. They are available in temperature ranges from 262F to 464F. I am starting with the lowest as I will not put them too close to exhaust or cylinder heads. I may decide to use higher cutoff temperature versions later on after test flying. I will install some thermistor temp sensors to measure actual temps during test flying.

All you need in addition to these is some 18 ga red wire(heavier gage for durability not amp draw), 1/8" and 1/4" heat shrink to go over solder joints and fusible link to prevent shorts, butt splices if desired, 1 amp fuse or cb, 12vdc 5-terminal relay from auto parts store. 12v power from fuse/cb to a series loop around engine compartment and back to relay coil to energize with master on. Jumper 12v pwr to common terminal of relay. Run ground to led and other relay coil terminal. Connect a 12v+ LED wire to NC terminal which will be keep the LED off as long as fire loop has continuity. Once fire warning led lights up you would want to confirm by other means that you do have a fire and not just a malfunctioning circuit. In the Blackhawk we got nuisance warnings occasionally. We had the luxury of opening the side windows and lean out to look with a harness on. In my RV-10 I will descend and circle tightly and look for smoke trailing behind, higher than normal fuel flow, open front heat vent for a second to smell. Once a fire is confirmed then fuel selector off, mixture pull, master off, etc. Will this give me 1-10 minutes notice- maybe. Will it get me excited even if there really is not a fire-probably. It may add another pound or so to the empty weight.

I think a fire extinguishing system for the engine compartment would only do you good once you were on the ground and airflow was near stopped. I will carry a 5 lb halon on top of the tunnel just for cabin fires or brake/wheel pant fires. I already have smoke hoods and combustible gas leak detector.
Still thinking about some thin stainless under tunnel bottom skin. I'll decide before my next acs order.

P.S. I installed a smoke alarm in every room in my house, crawl space and attic. All interconnected. Every once in awhile when I burn something on the stove they all go off- usually 6am when company is in town. Good wake up call. The military training I guess- Safety First.
 
Fire Suppression System

In the FWIW category:

My neighbor drives a Pro Nitrous dragster. A typical run is 1/8 mile (660 ft) with speeds over 194 mph. Numerous safety features as you'd expect for this sport.

He upgraded the fire suppression system to two 20 lb bottles for the 2011 season. Each bottle has its own firing cable. A manifold links both bottles to the stainless nozzle lines (two for the engine, one for the driver).

Some rules for these cars:
1. FIREWALL: Magnesium, aluminum or composite not allowed. All firewalls must be made of steel or titanium (.024 minimum thickness).
2. FLOORS: Replacing stock floors with .024″ steel or .032″ aluminum allowed. Driver?s side floor pan must be .024″ steel and must be welded in place extending from firewall to back of driver?s seat.
3. FIRE SYSTEM: SFI 17.1 system required. System must contain a minimum of 20 lbs of fluid or gas fire suppression agent. One nozzle required inside driver?s compartment must be directed at driver?s feet. Two or more nozzles must be directed at front of engine and fuel cell.
4. PROTECTIVE CLOTHING:A driver?s suit meeting SFI 3.2A/15, gloves meeting SFI 3.3/15, shoes meeting SFI 3.3/15 and a head sock meeting SFI 3.3 required. A head sock is not required when a helmet manufactured with a skirt meeting SFI 3.3 is used.
5. An external master electrical shut off clearly labeled ?PUSH OFF? is required.

His mental checklist for a fire:
1. Control the car (chute, brakes, etc.)
2. Kill the fuel.
3. Kill the electrical system.
4. Pull the suppression system handles (first #1; if fire continues, pull #2).
5. Get out :cool:
 
What I was thinking of is a warning system.

That is what Firewire systems like this are for: http://www.kiddegraviner.com/Files/KiddeGraviner/Global/US-en/Firewire_Thermal_Sensing_elements.pdf
They offer area heat detection not single point heat detect.

They have these sort of things running around jet engines for exactly this purpose. Have no clue what sort of price tag these have but probably not cheap.
Also don't know how easily it could be interfaced to an Experimental EMS.

Some jet engines have these attached to the engine cowl (hence I assume they must be 'disconnectable') so I guess you could attach one around the inside of an RV cowl half of your choosing.
 
With all the talk about fires, I was wondering if anyone has an extinguisher that can be discharged into the cowling while in flight like jets and helicopters do? This seems like a nice safety option if the price is reasonable. I have made my interest in this type of system known to a major manufacturer of these systems and told them there are many of us who may be interested if the price is reasonable. Since this is a non certified experimental market, the cost should be reasonable according to my contact. They are looking into it now.
The tricky part is ensuring that the extinguishing agent is distributed in the correct amounts at the right places so the concentration of the agent is enough to put out the fire, no matter where it is. Manufacturers of transport category aircraft do quite a bit of testing to get the fire extinguisher agent nozzle sizes and locations correct. In my experience working with one major manufacturer, it usually takes them several iterations to get the system tweaked so the agent concentration is high enough everywhere to do the job, and the guys who did the initial design would have the knowledge of what worked on previous aircraft models.

The airflow patterns under our cowlings are pretty hard to predict. The odds that some random guy who has never done this before getting the nozzle size and locations correct on his first attempt is pretty low. So, go down this road if you want, but you'll never know whether it works until the day you need it.
 
The odds that some random guy who has never done this before getting the nozzle size and locations correct on his first attempt is pretty low. So, go down this road if you want, but you'll never know whether it works until the day you need it.[/QUOTE]

Kinda like a parachute....great if it works, not so great if it doesn't.
 
170 driver said:
Kevin Horton said:
The odds that some random guy who has never done this before getting the nozzle size and locations correct on his first attempt is pretty low. So, go down this road if you want, but you'll never know whether it works until the day you need it.


Kinda like a parachute....great if it works, not so great if it doesn't.
Not really. If you buy a parachute from an established manufacturer you can be quite confident that it will work. Cobbling together an engine fire extinguisher system would be like someone who had never seen a parachute, nor had any idea how they were packed nor how a parachute harness was built, designing, fabricating and packing his own parachute because he was worried about his wings folding up. Maybe it would work, but there is a good chance it wouldn't. The effort put into designing his own parachute would be better spent in ensuring the wings don't fold up.

The effort put into cobbling together an engine fire extinguisher system that may or may not work would be better spent on ensuring a fire never starts in the first place. Use the best possible design practices and materials, have the installation critiqued by multiple qualified people, inspect it often in service, and replace flexible hoses at the recommended intervals.
 
Engine compartment Fire extinguisher

A friend forwarded me this discussion and I thought I would share my thoughts and system. I routinely use my RV7 for work travel to Stratford, CT and West Palm Beach, FL to conduct flight test. I normally cruise at FL 170 up to 190 taking advantage of the low fuel flow while running LOP. That said, the thought of having a fire at those altitude left me with no options other than finding the nearest CB, putting the plane into a spin, and hoping the the cloud would snuff the fire (this was actually NATOPS procedure for inadvertent IMC back in old days). The system I installed is designed for race cars, its a 3lb Halon bottle, 15 sec discharge time through 3 nozzles spraying at an angle of 150 degrees. I mounted two nozzles over the cylinder banks and the other one aft of the baffling over the engine accessories. I'll save the hand held for the cabin. The EP procedure following detection would be, pull nose up sharply, fuel shut off, mixture ICO, fire bottle prior to stall. My hope is to minimize airflow through cowl. This installation was done for about 400.00 dollars and is mainly peace of mind. If anyone need pictures tell me how to post them or shoot me an email.
Blue Skies,
Carey

CW3 Carey T. Mills
Experimental Test Pilot
U.S. Army Aviation Flight Test Directorate
Redstone Arsenal, AL
[email protected]
 
I installed a halon bottle in my fwd baggage compartment with two nozzles directing the halon in 150 deg pattern each centered on the most likely locations for a fire - fuel and oil hose connections most of which are above the lower deck of the engine and behind the accessory case in which little air flow exists. No idea if it works but the volume is small, air flow low, and halon is a proven fire suppressant. In addition to regular and proper inspections and maintenance its yet another tool in the arsenal.
 
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