Landing Gear Retraction Failure After Takeoff
You are the pilot of a light twin-engine piston aircraft departing from a 1,200 m runway at a sea-level airport. The outside air temperature is 30°C, and the aircraft is at maximum gross weight. After liftoff, you select gear up, but the landing gear indicator shows three green lights (gear down and locked) and you hear no retraction noise. The gear unsafe warning horn does not sound. The aircraft has a hydraulic gear system with an emergency hand pump. The gear selector is in the UP position. You are climbing through 500 ft AGL. The engine gauges show normal oil pressure and temperatures. The ammeter shows a slight discharge, which is normal after gear retraction due to the electric hydraulic pump. You have 3 hours of fuel and are 30 minutes from your destination. The weather is clear.
1. What is the most likely reason the gear did not retract, and what immediate actions would you take?
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The most likely reason is that the gear retraction did not occur because the hydraulic pump did not build enough pressure, or the gear selector linkage failed, or the gear was not fully retracted due to a mechanical obstruction. The three green lights indicate the gear is still down and locked. The absence of retraction noise suggests the hydraulic actuator did not move. The slight ammeter discharge is normal for the electric hydraulic pump, but if the pump ran and the gear did not move, there may be a hydraulic fluid leak or a pump failure. Alternatively, the gear selector may not have engaged the hydraulic valve.
Immediate actions: (1) Maintain aircraft control and climb to a safe altitude. (2) Check the gear selector is fully in the UP position. (3) Check the hydraulic fluid quantity and pressure gauge. If pressure is low, the pump may have failed. (4) Attempt to recycle the gear: select DOWN, then UP again. (5) Check the circuit breaker for the hydraulic pump; if popped, reset it once. (6) If the gear still does not retract, leave the gear down and plan to return for landing.
You should not continue the flight with the gear down, as it increases drag and fuel consumption, and you may exceed the gear extended speed if you climb too fast. You should reduce power and airspeed to stay below VLE (maximum landing gear extended speed). Notify ATC and request a return to the airport.
Before landing, you should consider that the gear is already down and locked, so landing should be normal. However, you should check that the gear is truly down and locked (three green lights) and that the emergency extension is not needed. You should also consider the possibility of a hydraulic leak; if so, you may have limited braking or nosewheel steering.
Given the clear weather and 3 hours of fuel, you have time to troubleshoot, but you should not delay unnecessarily. The key judgement is to recognise that the gear is not retracting and to decide to return rather than continue with the gear down, which would be inefficient and possibly unsafe.
2. If you decide to continue the flight with the gear down, what factors would you consider and how would you manage the flight?
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Continuing with the gear down is possible but has significant penalties: increased drag reduces climb performance, cruise speed, and range. In a light twin at maximum gross weight and high OAT, climb performance may be marginal. You must calculate the new performance: with gear down, the climb rate may be less than 200 ft/min, and the single-engine climb performance may be negative. You should consider the terrain and obstacles along the route.
You would need to reduce speed to VLE, which is typically around 140-160 KIAS for light twins. This reduces true airspeed and increases fuel consumption per mile. You have 3 hours of fuel, but with gear down, range may be reduced by 30-40%. You should recalculate fuel endurance and ensure you have enough to reach destination plus reserves.
You should also consider the possibility of a hydraulic leak causing the gear not to retract. If there is a leak, you may lose hydraulic pressure for braking and nosewheel steering. You should test the brakes and steering before landing.
In flight, you should monitor the gear indication continuously to ensure it remains down and locked. If any green light goes out, you may have a gear unsafe condition.
You should also consider the increased noise and vibration, and the possibility of overheating the hydraulic fluid if the pump is continuously running.
Operationally, you should notify ATC of your status and request a lower altitude if needed for performance. You should plan for a longer flight and possibly a fuel stop.
However, the safer decision is usually to return to the departure airport if the gear cannot be retracted, unless the flight can be completed safely with the gear down and there is a compelling reason to continue (e.g., medical emergency). In this case, with clear weather and a 30-minute flight, returning is prudent. The key judgement is to weigh the risks of continuing with degraded performance against the inconvenience of returning.