Rejected Takeoff Decision at V1 After an Unannounced Thrust Loss
A four-engine cargo aircraft is cleared for takeoff on a 3 200 m dry runway at a sea-level airport, OAT 32 °C, calm wind. Takeoff weight is 285 000 kg, V1 is 148 kt, VR 156 kt, V2 162 kt. At approximately 140 kt the flight engineer observes the number-three engine's N1 rolling back and EGT rising toward the limit; the master caution has not yet illuminated. The captain, flying, has both hands on the yoke and is calling airspeeds. Acceleration appears normal but slightly reduced. There are 2 600 m of runway remaining. The aircraft is below V1 and below VR.
1. Analyse the decision to reject versus continue, and identify the information the flight engineer must supply immediately.
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Below V1 the takeoff is rejectable, and the decision belongs to the captain; the flight engineer's job is to give the captain the facts fast and unambiguously. The key facts are which engine, what the N1 and EGT are doing, whether there is any fire warning, and the airspeed trend. A simple call such as 'number three rolling back, EGT high, no fire warning' is more useful than a long description. Continuing is only safe if the aircraft can achieve the required climb performance with the engine failed; on a hot day at high weight, second-segment climb gradient with one engine out may be marginal, and the flight engineer should say so. Rejecting from 140 kt on a 3 200 m runway leaves about 2 600 m, which is normally sufficient for a stop, but brake energy and tyre limits must be respected. If the rollback is confirmed and the aircraft is still below V1, the conservative choice is to reject, because continuing commits the crew to an engine-out departure with unknown performance margins.
2. If the captain elects to continue, what performance and handling considerations govern the climb-out?
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With one engine failed, the aircraft must satisfy the second-segment climb gradient requirement (for a four-engine aircraft, historically 3.0 %) at V2 with the gear up, the takeoff flap setting, and the critical engine inoperative. At 32 °C and 285 000 kg that gradient may be the limiting factor, so the flight engineer should verify the engine-out climb capability from the performance data for the actual weight, pressure altitude, and temperature before the aircraft reaches V2. Handling considerations: the yaw from the failed outboard engine must be countered with rudder, and the aircraft should be cleaned up on schedule - gear retracted at a positive rate, flaps retracted at the prescribed speeds - because drag reduction directly improves the gradient. The crew should not attempt to return for landing until the aircraft is at a safe altitude and the appropriate engine-out checklist is complete. The flight engineer monitors N1, EGT, and fuel on the remaining engines and confirms no secondary damage. If the gradient cannot be met, the crew must be prepared to land straight ahead or at the nearest suitable airport.
3. What must be recorded and reported after the event, and which documents drive the maintenance action?
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The event must be entered in the technical log with the time, phase of flight, engine parameters observed, and the action taken. Because an engine parameter exceeded or approached limits, an engine condition-monitoring report should be raised so maintenance can trend the data. If the engine was shut down or a limit was exceeded, the occurrence may meet the definition of a serious incident and must be reported to the authority within the prescribed time; the operator's safety management system also requires an internal occurrence report. The maintenance organisation then uses the approved troubleshooting manual and the engine manufacturer's limits to decide whether borescope inspection, chip detection, or a full shop visit is required. The aircraft cannot be returned to service until the defect is rectified or covered by an MEL entry, and the release to service must be signed by authorised maintenance personnel.