While the chances of a fire caused by a lithium battery are very small, fire in the aircraft in general is one of a crewmember’s worst fears. The seemingly specialized nature of a lithium battery fire makes pilots and flight attendants even uneasier, and with good reason.

I wanted to take the opportunity to explain a little about Lithium battery fires and what we teach at Aircare FACTS as part of our emergency procedures training for business aviation pilots and flight attendants.

A lithium ion battery (LIB) is known as a secondary battery because it is reuseable and rechargeable. A typical lithium battery in a laptop contains multiple cells, three to nine, all packaged together, side by side in a single ‘battery pack’. Each cell has three functional sections that are coiled up together and enclosed in a single pressurized casing. These sections are the positive electrode, which is usually made of lithium cobalt oxide; the negative electrode, typically made of carbon; and the separator that keeps the electrodes from touching each other. The cell also contains electrolyte which flows between the three sections and conducts the lithium ions. Lithium ions from the positive electrode (the lithium cobalt oxide) move to the negative electrode (the carbon) during charging and
	A cylindrical Lithium-ion cell
when in use they move back to the lithium. Lithium ion batteries get hot because they are incredibly energetic and the chemical reaction inside converts to electric and heat energy when being charged and discharged.

The battery pack also contains other components such as a temperature sensor, a voltage regulator and even a tiny computer that monitors the charge state. These components draw power from the pack even when the device is shut down.

'Thermal Runway'

The cool thing about LIBs, pun intended, is that they are very small, lightweight and pack a tremendous amount of power in them as compared to those heavy batteries that you use in your flashlight or the TV remote. The not so cool thing about LIBs is that they are much more reactive and volatile than traditional “dry cell” batteries. When exposed to excessive heat or when overcharged they can enter a state called ‘thermal runaway’ and then bad things happen.

I like to think of thermal runaway as my goofy dog chasing his tail. He’s lying there quietly and then some defect, in his case a severe mental short circuit, causes him to notice his tail. This excites him and his tail wags a little more causing him to take even more of an interest. He gets more excited and this causes his body to move and he lunges with his head. The more he moves the faster he chases until he’s running around in circles in an idiotic blur.

The National Transportation Safety Board is carrying out a detailed, microscopic investigation of the battery that caught fire on board a Boeing 787 Dreamliner in Boston earlier this month. All 50 Dreamliners remain grounded around the world.

Normal, properly manufactured LIBs don’t go into thermal runaway and they have several safeguards in the cell design and in the battery pack that are supposed to prevent this. Thermal runaway in an LIB occurs when a defect in the battery, for example a tiny piece of metal inside the cell that was left during manufacturing, suddenly connects or short circuits the positive and negative electrodes internally. This causes the cell to discharge irregularly and overheat. As it overheats the chemical reaction increases and consequently so does the overheating. It gets to a point where it’s out of control. This can occur during charging, using or even storing the device. When the temperature of the cell gets to a certain point the pressure causes the cell to essentially explode causing even higher temperature when the electrolyte ignites (around 1700º F or 927º C). Meanwhile the cell has gotten so hot that it has caused the adjacent cell to also go haywire, and it may also enter a state of thermal runaway. It keeps going this way until all of the cells in the battery have exploded. This may take fifteen minutes or less for all the cells to go off.

Cells erupt violently. When they go they usually take part of the cell casing with it, as well as the battery housing, and the device chassis with it. There is also usually a large flame caused by burning electrolyte that is incredibly hot. It’s not good.

The FAA has done some pretty extensive research on this subject as well as techniques to battle an LIB fire on the aircraft. The results and recommendations can be found on FAA SAFO 09013. At Aircare FACTS Training we teach these procedures combined with additional techniques to business aviation crews. We also developed a product called the Aircare FireSock to help with LIB fires on the plane.

If you see a smoking laptop on the table, be glad

One thing that I tell pilots and flight attendants when they call us is that if you are at FL 35 and you see a smoking laptop on the table, be glad. Well, wait until you are safely on the ground, but when you finally are, be glad that the laptop, phone or tablet wasn’t in the cargo hold and that you didn’t discover the fire because a warning went off on the flight deck. A smoking laptop on the table is a best-case scenario because it’s right there, you can see it happening, you know what’s causing it and you can do something about it immediately.

Your mission in life at this point is to protect yourself, your passengers and to stop thermal runaway from proceeding. Stopping thermal runaway immediately will stop all other bad things that go along with it from happening such as smoke, secondary fire or in a worst case scenario a class D fire. A class D fire is when metals such as magnesium or titanium get hot enough to ignite. Once this happens there is very little that can be done to stop it and there is no fire fighting equipment on board that can put out a class D fire. Because of it’s light weight, many of today’s laptops are made from magnesium alloys. The older Apple Titanium models were actually made out of titanium.

Recommended procedures for Lithium Battery fires in aircraft

Here is what we recommend for procedures for Lithium Battery fires in aircraft:

1. Inform the PIC. Tell them the situation so they can start their checklist.

2. Move passengers away from the device and NEVER attempt to touch it or move it.

This incident is automatically causing a series of things to happen including fire fighting, smoke removal procedures, flight diversion, preparation for emergency landing, and coordinating a planned evacuation. The last thing you want or need is to add a medical emergency to this list or to have a pilot or flight attendant incapacitated. Keep yourself in the game. Move passengers to a safe location. If you have supplemental smoke hoods tell them where they are and have them put them on.

3. Remove power from the device if it is plugged in. Some business aircraft have a dedicated circuit breaker for the 110 VAC outlets in the cabin. If so turn them off. If not, then try to pull the plug. If you need to get close to the device to do this then wait until you’ve gathered your equipment and donned a smoke hood and gloves.

4. Gather your equipment. You’ll want your PBE or smoke hood, gloves, water extinguisher, halon extinguisher and bottles or containers of water or other non-flammable liquids. Ask for help gathering these things if you need it.

5. Don PBE (or smokehood) and gloves. This will not only protect you from toxic smoke but also help protect your hands and face from flying debris or fire. Remember that these don’t make you invincible. Keep your distance.

6. If you see flames use the halon extinguisher to knock down the fire. This could be the device burning or secondary fire caused by the device (papers, upholstery, veneer etc). The Halon extinguisher is not going to stop thermal runaway because it does not cool the device.

7. Begin dousing the device with water. The whole idea here is to cool the device and bring the temperature of the battery cell down so that thermal runway stops (like when I clap my hands to get my dog to stop chasing himself). You can use the water extinguisher to put some distance between the device and yourself. If you’ve never used a water extinguisher before you might be surprised how quickly it empties. Once you’ve expended it, begin dumping bottles of water directly on the device. The FAA says about three 12oz bottles may do the trick but you may need more if the device is closed or in a awkward position.

8. Don’t smother the device! Throwing a blanket, pillow or even a bucket of ice on the device is not going to stop thermal runaway and in most cases it will actually insulate it, further promoting thermal runaway.

9. Once you’ve dumped a decent amount of liquids on the device, keep your eyes on it or have someone watch it for you in case thermal runaway begins again.

This is the point where the FireSock is employed but I’m not going to get into that here.

10. Continue with your checklist of emergency procedures, smoke removal, cabin and passenger preparation for evacuation.

If you’re not already, we also recommend that you become more conscious of where laptops and devices are being stowed. This is especially true if you are deadheading and your laptop is sitting in the cabin. You may decide to change standard operating procedures so that devices are no longer carried in the hold.

A lithium battery fire on an aircraft is not nearly as fun to watch or as concerning as my dog chasing its tail. But a good understanding of what is happening and the fundamentals of how to make it stop may be your second best friend.

Aircare Solutions Group, headquartered in Olympia WA., is comprised of business aviation companies that combined, provide Crewmember Emergency Procedures Training, Tele-medical Assistance, and Quality Crew Staffing to flight departments worldwide: 

www.aircaresolutionsgroup.com

324 West Bay Dr NW

Suite 200

Olympia WA 98502

360.754.9805

©BlueSky Business Aviation News | 31st January 2013 | Issue #209

.

BlueSky - your weekly business and executive aviation news - every Thursday

.