Safecraft Fire Extinguisher

I'm sure this will create another never ending debate so here goes...

Purchased a Safecraft 3lb halon fire suppression system from Spruce. Component wise it looks to be a very high quality system. It comes with a 3lb halon bottle (full), a bowden type fire T-handle (with FIRE labeled on a red handle), a mounting bracket with two hose clamps, 10ft of 1/4 alum (here we go) tubing, flared hardware (steal) and three nozzles (two for engine compartment and one for cockpit).

The bottle has a discharge head with two discharge ports. It is a one shot all or nothing deal. Pulling the T-handle removes the pin which opens the valve. The pin cannot be replaced (not inflight anyway).

I have several decisions to make:

1. Do I put two nozzles in the engine compartment and one in my electrical bay (which is that weird fwd baggage compartment to the right side - it is covered).

2. If I go with both locations should I put a valve in the ckt to allow me to select the source of the fire (engine or electrical)?

3. Where should I point the nozzles in the engine compartment? The nozzles have a 120 degree dispersal pattern. Since fuel and oil lines are left of centerline it wouldn't make any sense to put halon aimed to the right but rather spray from the right to the left keeping the fire contained at the possible sources. I'm drawing upon my recent completion of Naval Aviation fire fighting school (which is required for us every 4 years) but this is a stretch since the course doesn't cover internal nacelle fires. Maybe one nozzle pointing toward left center and the other covers the firewall from near the top pointing down toward the firewall. I think on this for a bit...

anyone else installed this?

I'm using a dynon EGT thermocouple as a fire detector which will be located at the center of the cowl exit. Not sure what the set point will be - 500-600 degree?

This should be an interesting discussion given the recent activity concerning firewall insulation....

Ken

Interesting

I'm looking a the same system and was wondering some of the same issues. I think a cockpit nozzle is important. Regarding the engine compartment, I think it would matter if the engine was carbureted or not. With fuel injection you've got the fuel spider and lines on top of the engine.

I would be inclined to put one on top and one on the bottom.

Hope you get some other responses. I'll be watching.

I have a carb so all fuel goes from lower left firewall through FF sensor lower centerline (alum tube - firesleeved) then firesleeved flex tube to the engine fuel pump to the left side of the carb. Oil cooler is mounted low on the engine mount on the left side so all oil lines are left of center as well.

I think spraying halon from about mid way up the firewall from right to left makes sense to me.

upon further consideration, I'm going to put all 3 nozzles in the engine compartment as I have another portable for the cockpit. I think I direct two towards the fuel sources as I've described and the third hi on the firewall as blanket protection for the entire firewall.

Its really about piece of mind since the only way to know if it works is in a real fire and then it either does or doesn't.

I won't worry about my children cause they are always bubble wrapped in a shelter to avoid meteorites (response to a comment in another thread)

A good discussion on this here thread

Highlights to me (and other thoughts):

1. Such a system is most likely only effective on the ground i.e. to save the aircraft from (further) damage, but not life saving.
2. If it was to be any use in the air, you'd need to slow the aircraft to the stall, then operate it (even then, airflow through engine area would probably render it fairly ineffective).
3. There is a recommended drill in that thread to survive an in-flight fire - basically dive beyond VNE and get on ground ASAP. This action is 100% opposed to that above, and may also assist in "blowing" out the fire / reducing the temperature.
4. Certified aircraft that have such systems do extensive flow testing to detemrine where to locate items... which we do not have results of.
5. All FF hardware should be SS.
6. Waste of time putting anything on top e.g. near spider in the "cooling flow"... Might be better aft of the baffle area around fuel / oil lines.
7. A single point detector, especially in the cooling exit, unlilely to work. Can you source / fit something like a jet would use i.e. a firewire?

There is not a lot of history v in flight fires to judge this area on. At a guess, I would suggest it as worthwhile to really study your fuel / oil systems layout, and try to reduce the chances of leak / ignition i.e. ensure no fittings up "air" stream of exhaust / electrical area, reduce inspection intervals e.g. to 10 hours, replace components more often (annually?), over maintain engine / treat it gently [the RV-8 fire / fatality seems to have been triggered by engine coming apart]...

Andy

PS And I have been in close formation with a jet with an in-flight fire, at which point the pilot banged out, so I am not saying they do not happen

Aircraft fire safety - parachutes?

Ken,
Your fire suppression system thread is most thought provoking. It comes on the heals of one Dan H. started a while back regarding firewall protection which generated a lot of comments. No doubt fire hazard rates high on every pilot/builders mind. I've started hanging the engine on my "8" and am energized to take any/all actions to maximize crew safety. One could drive one?s self nuts chasing every singe option and still wind up getting killed by a run away port-a-potty truck or some other ignoble way to die.

What to do?

If the probability of this occurrence meets an individual?s threshold for action I wonder if investing in a couple of seat-back parachutes is the best answer. It is the only one I can think of that gets you away from the fire. Of course there is the "what if you are in the dead-man curve area (to low to bail and to high to exit). My answer to that is the same as we use in aerobatic circles. Keep your exposure to the DMC area at a minimum.

The probability of an in flight fire is low; very low, but we spend a high, very high, amount of anxiety on this issue. So the parachutes likely will just sit there never used but are very good at provided a sense of security.


Don

This whole issue is purely about individual level of risk tolerance and the steps (tradeoffs) we are willing to go to mitigate this risk. For me, this fire suppressant system with good build and maintenance are enough. I'll sleep easy enough.

The area directly behind the accessory case and firewall to the top of the cowl doesn't have much if any flow. So suppressant released from above going downward SHOULD (emphasis intended) be effective in at least protecting the firewall since it is a small space - assuming the fuel has been shutoff. It is only a guess, but for me a reasonable one that will give me piece of mind while I'm flying. Better can be the enemy of good enough.

I'll have a parachute with me when I fly so I agree!

On a side note, a lot of research has been done on fine mist water spray as a fire suppressant with great results. Not sure if adding anti-freeze changes the effectiveness though????

At Speed...Halon is Too

My neighbor runs a serious dragster, equipped with a Halon fire suppression system.

Last year they ran with a 15 lb bottle. Three nozzles (two in the engine compartment, one aimed at the drivers feet/inner firewall. Pulled the handle at speed after a nitrous explosion and resulting fire.

Based on the less than spectacular results, they now run a 25 lb bottle and hope they don't have to yank the handle again.

Okay, it's anecdotal and it's a dragster, not an RV. Having said that, the speeds are the same (dragster top end in the 1/8 mile is the same as normal cruise in a 7/8).

IMHO a 3 lb bottle of Halon sprayed into an engine compartment at speed won't do much.

I'd aim the nozzles at the inner firewall.

Good luck,
Mike

Halon

I see two issues here. First is the engine compartment. Spraying Halon in the path of the cooling air seems to me a waste of time. The extinguishing system pressure depletes in less than 10 seconds and will be blown through the cowling very quickly. In turbine engine installations the extinguishing agent is released in areas surrounding the engine with little airflow. Second, the thought of releasing the Halon in the cockpit has its own problems. The airflow is less, but the Halon is toxic and is intended to displace oxygen. Not a pilot friendly environment. Here is some information on the agent used in the Aircraft Spruce system:

http://en.wikipedia.org/wiki/Bromotrifluoromethane

John Clark ATP, CFI
FAA FAAST Team Member
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA

Fire needs three elements to prosper: fuel, oxygen and heat. The most common extinguishing agents like water, carbon dioxide, dry chemical and foams attack the fire physically to deprive the fire of one or more of the three critical elements needed for propagation. Halon differs in the way it puts out the fire. It offers some of water's cooling effect and some of carbon dioxide's smothering action, but its essential extinguishing technique lies in its capacity to chemically react with the fire's components. It actually interrupts the chain reaction of fire.

Water is very effective on class A fires (common combustibles like wood and paper). Halon is effective on common combustibles (although not as effective as water), but Halon is also effective on class B (flammable liquids), and it does not conduct electricity back to the extinguisher operator (class C).

Halon is similar to CO2 in that it is suitable for use in cold weather and leaves no residue. Unlike CO2, however, Halon does not displace the air out of the area where it is dispensed. Even for the toughest fires, less than an 8% concentration of Halon by volume is required, leaving plenty of air to use in the evacuation process. Also, unlike CO2, there is no danger of "cold shocking" avionics or other sensitive electrical equipment.

Dry chemical fire extinguishers are effective on A, B and C class fires. However, they are highly corrosive, and create billowing clouds of choking dust; dry chemical extinguishers should not be used in an aviation environment.

Foam extinguishers are effective on class A and B fires, and are particularly useful for preventing ignition of flammable liquid spills. However, foams are inferior to Halon in that they do require cleanup and in that they are not for use on electrical fires.

Halon 1211 is a liquefied gas which, when discharged, leaves the nozzle in a stream that is about 85% liquid and 15% gas. This gives the agent a range of 9 to 15 feet and offers significant advantages in fighting fires in large aircraft cabins. Mixtures of Halon 1211 and Halon 1301 have discharge characteristics dependent on the component weight ratio.

Halon Safer than you think

A 'lift' from HCR aviations web page:

Inhaling Halon

One of the issues associated with Halon use, especially in the tight confines of a cockpit, is ensuring adequate ventilation. According to FAA Advisory Circular AC 120- 80, In-Flight Fires, "NTSB investigations of in-flight fires indicate that crewmembers have been hesitant to use Halon extinguishers during flight because of mistaken ideas about adverse effects of Halon." The FAA notes, "The toxic effects of a typical aircraft seat fire, for example, far outweigh the potential toxic effects of discharging a Halon fire extinguisher."

Hopefully, discharging any extinguisher in a cockpit puts out the fire. But, discharging some extinguishers can create a whole new set of problems. Again, the FAA (from AC 20-42C, Hand Held Fire Extinguishers for Use in Aircraft): "Dry chemical extinguishing agents when discharged in crew compartments of confined areas may cause serious impairment to visibility. In addition, they may cause temporary breathing difficulty during and immediately after discharge." Our testing confirms these two cautions.

Some interesting points above. However,

but are very good at provided a sense of security

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is a common "theme".

Trouble is, a Parachute, or Fire Extinquisher system, might provide "peace of mind", but it is irrelevant, and even counter-productive, unless you have a "drill" on how/when to use them, knowing this will be more effective than another course of action... e.g.:

Parachute Who has got out of an RV successfully? The canopies are rumoured to want to close, and therefore "escape" might not be possible, especially say from the rear of an RV-8. If you lead this on, you might consider a jettisonable canopy system... but that has it's own hazards I fly a(nother) type that says inadvertant loss of the canopy is likely to render the aircraft uncontrollable, and now you need to balance the risk of the one-off jettison system killing you by itself Somebody in this area lost the canopy of a type not a million miles different from an RV-8, and the aircraft, tail damaged but intact, had to be force landed immediately, writing off the aircraft - the pilot said the trim change was such it was "unflyable". RV-8 has a compartively larger canopy / weaker tail, and I suspect loss of an RV-8 canopy = no tail

Fire Extinquisher When / how will you use it? After closing off fuel / ignition? After waiting another 30s for things to cool a bit? After slowing aircraft to the stall? But would all this time be better used just throwing the thing on the ground anyway? As above, "cooling" is an important extinguishing factor... but high IAS is the best cooling mechanism we have...

An interesting debate... answers will be more difficult

Andy

In regards to bailing out..........

You always have to ask yourself, what's the un-controlled aircraft potentially going to hit.

L.Adamson ---- RV6A

It's been done

Canopies have come off of RV-4s with no damage to the tail. At least one pilot bailed out of a -8. Sadly, sans parachute. My plan for an uncontrolable fire is bailout. I bought my chute after reading about the -8 guy and have flown with it every single flight since.

L.Adamson said:

In regards to bailing out..........

You always have to ask yourself, what's the un-controlled aircraft potentially going to hit.

L.Adamson ---- RV6A

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What is it going to hit with my charred body still inside? Certain death vs a chance of hitting something is a simple decision for me. Thousands of objects fall to the earth every day and very few cause damage much less injury/death.

cguarino said:

What is it going to hit with my charred body still inside? Certain death vs a chance of hitting something is a simple decision for me. Thousands of objects fall to the earth every day and very few cause damage much less injury/death.

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For comparison's sake......................if a thousand airplanes fell to the earth every day, it would be a different story.

Of course, if it's over a sparsely populated Texas desert, as well as our Utah deserts, then that's something else altogether.

But personally, if I'm in good enough shape to bailout, I'd do everything possible to prevent an aircraft from going down in any populated area, if I can help it. Even at my expense. At the moment, I wouldn't have a choice anyway, as I don't carry chutes.

Around eleven years ago, a young CFI had to make that choice. A firewall forward fire developed due to a bad exhaust joint (turbo section)on a relatively new certified aircraft. He couldn't make it back to the airport, and dove it in between two home foundations, rather than risk hitting many homes just beyond. At least that's the speculation. What brings it home to me, is that it was right across the street.

Going back farther, I remember looking down over the expanse of wheat fields as I made the crosswind turn on my solo flight. Turns out I was looking exactly where my subdivision is now.

L.Adamson ---- RV6A

What you can do and want to do

L.Adamson said:

But personally, if I'm in good enough shape to bailout, I'd do everything possible to prevent an aircraft from going down in any populated area, if I can help it. Even at my expense.
L.Adamson ---- RV6A

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I come from a military background and I was brought up to believe that if I was going to eject it was because the jet was uncontrolable or on fire and soon to be uncontrolable. The one exception is what we called a controlled bailout and that is done in a specially designated, uninhabited area. Staying with an out of control aircraft just doesn't make sense. You can't avoid houses if the aircraft is uncontroable and if you are on fire, you will be looking for the first open piece of ground you can find. Staying with an airplane that you can't control (for either mechanical or physiological reasons) is just not prudent. Now, go buy a chute.

Install pics of the SafeCraft Halo system I bought:


All I need to do is send the bottle to SafeCraft to have a pick-up tube installed since I mounted the bottle horizontally. I have two nozzles in the engine compartment covering the entire lower half of the firewall as well as all fuel and oil lines. I really hope I never need it. I'll install a thermocouple for a sensor tomorrow.

The T-handle is just forward of the fuel selector making this an easy one hand (left hand) procedure.

Nozzle in engine compartment..