Presentation on theme: "Hot Brakes & Wheel Assemblies Randy Krause Port of Seattle Fire Department Fire Chief October 2010 To Promote the Science and Improve the Methods of Aviation."— Presentation transcript:
Hot Brakes & Wheel Assemblies 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 1973
ER Video 2002
787 Brake Test 2010
OBJECTIVES Causes of Hot Brakes Hazards Extinguishing agents Approaching the aircraft? New Technologies (The science)
Causes of Hot Brakes Aircraft weight – –Landing with excess weight (extra fuel) –To short of runway for the aircraft weight and size Landing speeds –Reverser malfunction –Short runway Extraordinary braking –Short runway –Reverser malfunction Refused take - off (RTO)
New Technology What is the wheel assembly/brakes made of? Cera-metallic Aluminum alloy Carbon Composite Note: Today magnesium and titanium are not being used in the commercial aircraft wheel assemblies or braking systems.
Hazards Tire failure –Blow out due to age or other factors such as FOD, over inflation, or it just wears out. (where does tire fail) Fusible plugs –Failing 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 aft
Approaching the Aircraft Establish communication with pilot –Let 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 ?
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.
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 tires shoulder. Michelin Recommended Approach
NFPA 402 Recommendation 12.4 Hot Brakes and Wheel Fires 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 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 Foam, water spray, halogenated agent, and dry chemical are effective agents for direct application on brake fires 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 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 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.
5 th 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. Fans – 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. Handlines 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 cera-metalic, 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 todays commercial and military aircraft. These changes should be taken into consideration when addressing department policy in handling these types of emergencies.
ICAO Language 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 cooling is desired after extinguishment of the fire, the agent should be directed at the brake area only.
ICAO Language 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.
Extinguishing Agents Dry chemical Dry powder Water –Plentiful, available, cheap and environmentally friendly Foam Dual agent
BUCKEYE FIRE EQUIPMENT COMPANY Use of ABC Dry Chemical Fire Extinguishers on Aircraft Fires The 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 aircrafts 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.
Boeing Dry Chem Recommendation SUGGESTED OPERATOR ACTION: Boeing recommends that operators and airplane maintenance providers take positive actions to prevent 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 Halon or Halon 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.
Boeing Flight Test Minor temperatures – Heat waves observed, minor smoke light blue in color. –Water or air cool Extreme 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 reach
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 All-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 monoammonium phosphate are popular has to do with corrosion. Any chemical powder can produce some degree of corrosion or other damage, but monoammonium 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."
Water When using water: As much as available to prevent warping the axle. Use hand line / HRET / turret –Booster reel for hot brakes –Combat line or turret for brake fire Cool entire wheel and brake assembly Be aggressive! –Which means be quick, and careful
Questions? To Promote the Science and Improve the Methods of Aviation Fire Protection and Prevention
Proper Approach – Forward of main gear truck 45 degree angle Full PPE SCBA on 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.
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.
What are we going to do ? Is there fire? –To the brakes –To the strut –To 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 Environment
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 aft 45 degree angle Full PPE Shields if equipped down or goggles on Two person operation The fan should be left unattended after placement
Cera-Metalic/Composite Brakes Standard on all modern aircraft Most (if not all) older Aircraft have changed to them –Will withstand higher temps than steel by absorbing and dissipating heat more efficiently –Less likely to fail due to rapid cooling
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?
Fire If fire is present: Small tire fire - use water Large fire - treat as any aircraft fire –attack with large amounts of water & if fuel cells are compromised use foam!
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 deflated Brakes are already warped! Water will not matter at this point
LANDING GEAR EMERGENCIES AND TIRE FAILURE
NOSE GEAR Tire Failure –Due to FOD –Age of tires –Over inflation Gear Damage –Due to FOD Gear not down and locked in place –Mechanical/Hydraulic failure –Damage caused by FOD Possible Belly Landing WATCH OUT!
Entire nose gear steering assembly failed to lock down in forward and was set for a starboard turn.
The wheel assemblies were ground flat. Damage to the gear assembly extended up into the gear bay and the strut assembly.
Half a wheel left after feet of runway dragging.