Hot Brake and Tyre Failure After a Rejected Take-off
A narrow-body jet rejects a take-off at 100 kt on a 2600 m runway. The calculated V1 was 135 kt, so the reject is well below V1. The aircraft stops with about 900 m of runway remaining. The brakes are carbon, and the brake temperature indicators show 420 degrees C on the left main gear and 380 degrees C on the right main gear immediately after stopping. The tyre pressure monitoring system shows normal pressures. The wind is calm, and the outside air temperature is 32 degrees C. The crew must decide whether to vacate and hold, request a tow, or continue the take-off after a brake check. The airport has a fire service and a run-up area.
1. Assess the brake energy state and explain why the temperatures are below the fuse plug threshold but still significant.
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The brake temperatures of 420 and 380 degrees C are below the typical fuse plug melting range, which is around 600 to 800 degrees C for carbon brakes, but they are well above ambient and indicate significant energy absorption. The reject from 100 kt is a low-energy event compared with a reject near V1, so the temperatures are moderate. However, carbon brakes can continue to heat after the aircraft stops because the heat is conducted into the wheel and tyre. The peak temperature may occur several minutes after stopping, so the crew should not assume the brakes are cool just because the indicator is below the threshold. The significance is that the tyres are at risk if the heat soaks into the wheel. The judgement is to treat the brakes as hot, hold the aircraft in position, and monitor the temperatures rather than immediately continuing.
2. Explain the risk of tyre damage and the correct procedure for cooling and inspection before further flight.
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The risk is that heat from the brakes conducts into the wheel and raises the tyre pressure, and in extreme cases the fuse plug melts to release pressure. At 420 degrees C, the fuse plug is not expected to melt, but the tyre pressure will rise. The tyre pressure monitoring system shows normal pressures, which is reassuring, but the pressure should be rechecked after the brakes cool. The correct procedure is to hold the aircraft in a safe area, keep the brakes off if possible to avoid further heat, and allow a cooling period. The crew should not apply the parking brake, because that concentrates heat in the brakes. After cooling, the crew should inspect the tyres and wheels for damage, check the pressures, and consult the brake temperature chart for the minimum turnaround time. The judgement is to wait for cooling and inspection before continuing, not to depart immediately.
3. Decide whether the crew should continue the take-off after a brake check or return to the gate, and justify the decision.
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The reject occurred at 100 kt, well below V1, so there is no requirement to stop for a failure above V1. The aircraft is on the runway with 900 m remaining, which is enough to vacate. The brakes are hot but below the fuse plug threshold, and the tyres are normal. The decision should be to vacate, hold in the run-up area, and allow the brakes to cool while monitoring the temperatures. Continuing the take-off after a short brake check would be risky because the brakes would be hot for the take-off and the subsequent landing, and the heat soak could affect the tyres. Returning to the gate is not necessary if the brakes cool within a reasonable time. The judgement is to hold, cool, inspect, and then decide whether to continue the flight or return to the gate. The final decision is to hold and cool, not to continue immediately.