Hot Brakes & Wheel Assemblies - PowerPoint Presentation

Hot Brakes & Wheel Assemblies
Hot Brakes & Wheel Assemblies

Hot Brakes & Wheel Assemblies - Description

Randy Krause Port of Seattle Fire Department Fire Chief October 2010 To Promote the Science and Improve the Methods of Aviation Fire Protection and Prevention Dash 80 Video 1954 Command Post Video ID: 135195 Download Presentation


aircraft fire dry wheel fire aircraft wheel dry brakes water chemical assembly cooling brake hot agent gear approach tire extinguishing agents fires

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Hot Brakes & Wheel Assemblies

Randy KrausePort of Seattle Fire DepartmentFire ChiefOctober 2010

“To Promote the


and Improve the Methods

of Aviation Fire Protection and Prevention”Slide2

Dash 80 Video1954Slide3

Command Post Video1973Slide4

747-400 ER Video2002Slide5

787 Brake Test 2010Slide6


Causes of Hot BrakesHazardsExtinguishing agentsApproaching the aircraft?New Technologies (The “science”)Slide7

Causes of Hot Brakes

Aircraft weight –Landing with excess weight (extra fuel) To short of runway for the aircraft weight and sizeLanding speeds

Reverser malfunction

Short runway

Extraordinary braking

Short runway

Reverser malfunction

Refused take - off (RTO)Slide8

New TechnologyWhat is the wheel assembly/brakes made of?

Cera-metallic Aluminum alloyCarbonCompositeNote: Today magnesium and titanium are not being used in the commercial aircraft

wheel assemblies or braking systems.Slide9


Tire failureBlow out due to age or other factors such as FOD, over inflation, or it just wears out. (where does tire fail)Fusible plugsFailing to operate as designed

Disintegration of wheel assembly

Explosive fragmentation due to tire failure or rapid cooling

Has anyone witnessed this? If so, why did it happen?

Danger zone ( Approx. 300 feet )

Outside of a 45 degree angle from gear truck centers forward and aftSlide10

Approaching the Aircraft

Establish communication with pilotLet the flight deck know by radio who you are, what the problem is, where you currently are, and where you want to go

Approach from front or aft or

45° angle


New approach or “old” school?

Type of aircraft

Lower wing aircraft and or engine placement may interfere with proper ARFF placement

Heavier aircraft = more gear trucks, wheels and brake assemblies

Observe tire condition

Are they inflated, deflated, appear larger than others or on fire

Is there smoke or fire ?Slide11

Boeing Recommendation

Approach Main Gear Along Arrows Never Enter Shaded Areas When There Is A Suspect Hot Brake Or Tire. Stay At Least 25 Feet (7.6 meters) Away From Tire Or Rim Until Temperature Returns to Ambient. Slide12

In service, tires should also be treated with care so as to avoid conditions that would damage the tire and wheel assembly or create a dangerous situation for those around the assembly or aircraft.• You should never approach, or allow anyone else to approach, a tire and wheel assembly mounted on an aircraft that has obvious damage until that assembly has been allowed to cool to ambient temperature. This cooling generally requires at least three hours.

Always approach a tire and wheel assembly from an oblique angle, in the direction of the tire’s shoulder.

Michelin Recommended ApproachSlide13

Tire BurstSlide15

NFPA 402 Recommendation

12.4 Hot Brakes and Wheel Fires.12.4.2 In order to avoid endangering ARFF personnel and aircraft occupants and causing unnecessary damage to the aircraft, it is important not to mistake hot brakes of brake fire. Hot Brakes normally cool by themselves and do not require an extinguishing agent.

12.4.4 ARFF personnel should remain clear of the sides of the aircraft wheel assemblies that are involved in fire and

approach only in a fore and aft direction

. Since heat is transferred from the brake to the wheel, extinguishing agent should be applied to the brake area. The primary objective is to prevent the fire from spreading upward into the wheel wells, wings, and fuselage.

12.4.5 Foam, water spray, halogenated agent, and dry chemical are effective agents for direct application on brake fires.

12.4.6 Dry Chemical agents and halogenated agents might extinguish fires involving hydraulic fluids and lubricants, but re-ignition can occur since these agents lack sufficient cooling effect. Halogenated agents are particularly effective in extinguishing undercarriage fires; however, where magnesium wheel components are burning, halogenated agents should not be used.

12.4.7 Effectiveness of any gaseous extinguishing agent can be severely reduced if wind conditions are such that sufficient concentration cannot be maintained to extinguish the fire.

12.4.8 Solid streams of water should be used only as a last resort on wheel fires since the rapid cooling can cause an explosive failure.

However, fires involving magnesium wheels have been successfully extinguished by applying large amounts of water from a distance. This method rapidly reduces the heat to a point below the ignition temperature of the magnesium, and the fire is extinguished,. ARFF personnel should exercise extreme caution when this method of extinguishment is used, as explosive failure of the wheel components is likely. Slide16

5th edition; IFSTA Language pg. 342

Acceptable Methods for cooling hot brakes include the following:Continue to Taxi – will assist in dissipating heat when appropriate; only useful if taxiing can be done without the flight crew applying the brakes; ARFF personnel should monitor this condition until it is determined to be safe.

Normal Cooking

– wheel assembly cools on its own in a remote area of the airport designated be ARFF personnel; ARFF personnel should monitor this situation until it is determined to be safe.

Water mist of fog pattern

– cools wheel assembly; water mist or fog pattern in a continuous flow is a suitable alternative and safer than using fans in most cases.


– air cools wheel assembly; suitable method to

expedite normal cooling

; most ARFF departments use portable fans, and this used places firefighters close to the hazard zone.

Wheel Fires pg 343.

If the wheel assembly is on fire, the safest approach is to use large amounts of water from a distance using turrets. This application keeps the firefighters out of the hazard zone and allows for extinguishment and rapid cooling. Once the fire is out, cooling efforts should be maintained to minimize damage to other components.


can be used in place of turrets as long as the

firefighters approach from a fore or aft position.

If water is not available, any suitable agent should be used to extinguish the wheel fire.

The use of combustible metals in the wheel assemblies is declining due to the increased weight of the metals and their tendency to accumulate rust.

New generation brake and wheel assemblies are constructed of


, aluminum alloy, and carbon posing less of a hazard than older generation assemblies, which contained small amounts of magnesium or titanium in their construction. These metals are rarely found in today’s commercial and military aircraft.

These changes should be taken into consideration when addressing department policy in handling these types of emergencies.


ICAO Language

12.2.3 Hot brakes and wheel fires. The heating of aircraft wheels and tires presents a potential explosion hazard, greatly increased when fire is present. In order not to endanger the members of the airport rescue and fire fighting service needlessly, it is important to distinguish between hot brakes and brake fires.

Hot brakes will normally cool by themselves without the use of an extinguishing agent.

Most aircraft operating manuals for propeller driven aircraft recommend that flight crew members keep the propeller forward of the fire turning fast enough to provide an ample cooling airflow. Most wheels of jet aircraft have fusible plugs which will melt at about

177°C and deflate the tire before dangerous pressures are reached.

When responding to a wheel fire, airport rescue and fire fighting members should approach the wheels with extreme caution in a fore or aft direction

, never from the side in line with the axle


“Since the heat is transferred to the wheel from the brake it is essential that the extinguishing agent be applied to this area. If further


is desired after extinguishment of the fire, the agent should be directed at the brake area only.Slide18

ICAO Language12.2.4 Too rapid cooling of a hot wheel, especially if localized,

may cause explosive failure of the wheel (is this a true statement). Solid streams of water should not be used except as a last resort. Water fog can be used but intermittent application of short bursts of 5 to 10 seconds eve:y

30 seconds is recommended.

Dry chemical has limited cooling capacity but is an effective extinguishing agent. Once the tires are deflated, any extinguishing agent may be safely used as there is no further danger of explosion.Slide19

Extinguishing Agents

Dry chemical Dry powder WaterPlentiful, available, cheap and environmentally friendlyFoamDual agentSlide20


Use of ABC Dry Chemical Fire Extinguishers on Aircraft FiresThe basic component of the extinguishing agent contained in an ABC fire extinguisher is mono-ammonium phosphate (sometimes referred to as MAP). The agent is very efficient at extinguishing Class A type fires because it “melts” and forms a crust on the surface of the burning material, creating an oxygen barrier. When used on an aircraft fire the agent can flow into minute structural cracks common in the aircraft’s stressed aluminum surfaces


There it can combine with moisture to form phosphoric acid, a chemical that is highly corrosive to aluminum. The residue is extremely difficult to clean up and failure to completely clean the agent from the aircraft will, over time, result in corrosion that could compromise the integrity of the aircraft. For this reason Buckeye Fire Equipment Company does not recommend the use of ABC fire extinguishers on aircraft.Slide21

Boeing Dry Chem Recommendation

SUGGESTED OPERATOR ACTION:Boeing recommends that operators and airplane maintenance providers take positive actions toprevent the use of dry chemical fire extinguishes in and around airplanes. This action should

include airlines and maintenance providers coordinating with airport authorities, maintenance,

fueling service providers, ground service providers, and airport fire services. Operator personnel,

maintenance and service providers, airport authorities and airport fire service personnel should be

advised through formal training programs or other appropriate means on the potential damage

that can be caused by the use of dry chemical fire extinguishers on airplane fires. Steps should be

taken to replace dry chemical extinguishers that are located near parked airplanes and installed on

airplane ground service equipment. The dry chemical extinguishers should be replaced as

appropriate with suitably rated water, carbon dioxide, aqueous film-forming foam (AFFF), and




replacement type fire extinguishers.

If a dry chemical extinguisher is used on an airplane, the airline should contact their assigned

Boeing Field Service Representative for specific advice and information regarding the removal of

dry chemical extinguishing agents from the affected area of the aircraft.Slide22

Boeing Flight Test

Minor temperatures – Heat waves observed, minor smoke light blue in color.Water or air coolExtreme temperatures – Glowing, open flames, moderate to heavy dark colored smoke

Cool with water

If Fusible Plug fails – Open flames, heavy dark colored smoke, slag dripping temperatures are extreme and a severe hazard exists!

Cool with large amounts of water preferably with turrets at maximum reachSlide23

Can I use a dry chemical fire extinguisher rather than Halon?

The best way to answer this question is to cite NFPA Standards and other published documents:NFPA 410 Aircraft Maintenance (Addendum) A-7-3.1All-purpose (ABC) dry chemical-type

extinguishers should not be used in situations where aluminum corrosion is a problem.

NFPA Fire Protection Handbook Chapter-Basics of Fire and Science

Extinguishment with Dry Chemical Agents:

One reason that dry chemical agents other than


phosphate are popular has to do with corrosion. Any chemical powder can produce some degree of corrosion or other damage, but


phosphate is acidic and corrodes more readily than other dry chemicals, which are neutral or mildly alkaline. Furthermore, corrosion by other dry chemicals is stopped by moderately dry atmosphere, while phosphoric acid has such a strong affinity for water that an exceedingly dry atmosphere would be needed to stop corrosion.

Air Transport Newsletter, by Ronald Horn, Nov./Dec.

1983, "Class A-B-C Extinguishers Damage Aircraft"

"The A-B-C extinguishers have excellent fire-fighting capability, but the mono-ammonium-phosphate chemical agent melts and flows when it comes into contact with heat. This is how it gets its Class A rating. This chemical is highly corrosive to aluminum, and once it contacts hot aluminum and flows down into the structural cracks and crevices it cannot be washed out as the B-C dry chemical agents can.

"Once an A-B-C extinguisher is used on an airplane, it is necessary to disassemble the aircraft piece by piece and rivet by rivet to accomplish cleanup. Failure to do so will result in destruction of the aircraft by corrosion."Slide24


When using water:As much as available to prevent warping the axle. Use hand line / HRET / turretBooster reel for hot brakes

Combat line or turret for brake fire

Cool entire wheel and brake assembly

Be aggressive!

Which means be quick, and carefulSlide25


“To Promote the Science and Improve the Methodsof Aviation Fire Protection and Prevention”Slide26

EICAS - Flight Display(Engine Indication Crew Alert System)Slide27

Proper Approach –

Forward of main gear truck

45 degree angle

Full PPE


Shields if equipped down

Nozzle man with backup

The use of a booster line, as in this picture; is only suitable for cooling brakes that have not yet erupted into fire. It is required that a combat line of no less than 1-1/2” be deployed when faced with a full on brake fire.

Work this one and replace. Slide28

Proper Approach –

45° and forward of inside aft gear truck

Full PPE

Shields if equipped down

Nozzle man with backup

The use of a booster line, as in this picture; is only suitable for cooling brakes that have not yet erupted into fire. It is required that a combat line of no less than 1-1/2” be deployed when faced with a full on brake fire.Slide29

What are we going to do ?

Is there fire?To the brakesTo the strutTo the gear bay or under wing structure

Do we need to evacuate the aircraft?

If the gear bay or under-wing structure is involved - YES

Can the aircraft taxi?

Is the aircraft on a hard surface

Are a majority of the main gear truck wheels intact and inflated?

Is the nose gear assembly intact and tires inflated?

What are my exposures?

People, Property the EnvironmentSlide30

Cooling hot brake assemblies with air is acceptable if the aircraft has made it to parking and is still experiencing hot brakes. After placing the fan, personnel should leave the immediate danger area and monitor the process while remaining in contact with the flight deck and in observation of the brake assembly.

Proper Approach –

Forward or


45 degree angle

Full PPE

Shields if equipped down or goggles on

Two person operation

The fan should be left unattended after placement Slide31

Cera-Metalic/Composite Brakes

Standard on all modern aircraftMost (if not all) older Aircraft have changed to themWill withstand higher temps than steel by absorbing and dissipating heat more efficiently

Less likely to fail due to rapid coolingSlide32

Proper Approach –

Forward and at 45°

Full PPE

Shields down

Is this tactically a good use of manpower?

Is this a safe stance to be in for this firefighter if things go bad?

If this was a fire, what is missing from the firefighters arsenal of PPE?

Can this firefighter effectively cool the entire assembly from here?Slide33


If fire is present:Small tire fire - use waterLarge fire - treat as any aircraft fireattack with large amounts of water & if fuel cell’s are compromised use foam!Slide34

Steel Brakes

Concerns surround the use of water on hot metal parts and whether more damage will be created due to the rapid cooling. With aircraft equipped with steel brakes if tires have deflatedBrakes are already warped!Water will not matter at this pointSlide35



Tire FailureDue to FODAge of tiresOver inflation Gear DamageDue to FOD

Gear not down and locked in place

Mechanical/Hydraulic failure

Damage caused by FOD

Possible Belly Landing

WATCH OUT! Slide37

Entire nose gear steering assembly failed to lock down in forward and was set for a starboard turn.Slide38

The wheel assemblies were ground flat. Damage to the gear assembly extended up into the gear bay and the strut assembly.Slide39

Half a wheel left after 1800+ feet of runway dragging.

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