Engine Failure After Takeoff with Obstacle
You are flying a light twin-engine piston aircraft from a 1200 m runway at an elevation of 1500 ft. Outside air temperature is 30°C, and the aircraft is loaded to its maximum takeoff mass. During the takeoff roll, just after rotation at 85 KIAS, the right engine fails. The aircraft yaws to the right, and you apply rudder to maintain directional control. The published single-engine climb performance at this mass, altitude, and temperature shows a positive rate of climb of 150 ft/min at VYSE (95 KIAS), but the obstacle clearance gradient required is 2.5%. You are now at 200 ft AGL with the gear still down and the propeller of the failed engine not yet feathered.
1. What immediate actions should you take, and what is the critical decision point?
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The immediate actions are to maintain directional control with rudder, pitch for VYSE, and identify and verify the failed engine. You must feather the propeller of the failed engine to reduce drag and improve single-engine performance. The gear should be retracted as soon as a positive rate of climb is established. The critical decision point is whether the aircraft can meet the required obstacle clearance gradient. At 150 ft/min and 95 KIAS, the climb gradient is approximately 150 ft/min divided by 95 knots times 101.3 ft per knot per minute, which gives about 1.6%. This is below the required 2.5%. Therefore, you cannot guarantee obstacle clearance. The correct decision is to abandon the takeoff, level off, and return to land, rather than attempting to climb over the obstacle. The priority is to maintain control and land safely, accepting the possibility of a forced landing if necessary.
2. How does density altitude affect the single-engine climb performance in this scenario?
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Density altitude is the altitude at which the aircraft would perform as if it were at that altitude in standard conditions. At 1500 ft elevation and 30°C, the density altitude is significantly higher than 1500 ft, perhaps around 3000 ft or more. This reduces engine power output and propeller efficiency, and it increases the true airspeed for a given indicated airspeed. The published single-engine climb rate of 150 ft/min is already at the limit, and the higher density altitude means the actual climb rate may be lower. The climb gradient is also affected because the true airspeed is higher, so the aircraft covers more ground distance per minute for the same rate of climb, reducing the gradient. This reinforces the decision not to attempt obstacle clearance and to land as soon as possible.