Unexplained Control Force After Maintenance
You collect your aircraft after a 100-hour inspection. The maintenance organisation replaced a main landing gear tyre and adjusted the aileron control cables. On the pre-flight you notice the ailerons move freely and return to neutral, but the control wheel feels slightly stiffer than you remember. During the take-off roll at 50 kt the aircraft begins to veer left; you correct with right rudder and it responds normally. At rotation the aircraft lifts off and you notice a small but persistent right-wing-low tendency that needs continuous left aileron to hold wings level. There is no vibration, no abnormal engine indication, and the fuel gauges read normally. The aircraft is otherwise flying normally and you are 400 ft above the aerodrome.
1. Assess the significance of the right-wing-low tendency and state your immediate actions.
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What it means. A persistent wing-low tendency requiring continuous correction is a control-rigging or asymmetry problem until proven otherwise. The maintenance organisation adjusted the aileron cables, and the most likely explanation is that the rigging is not symmetrical, giving a small permanent aileron deflection. Other possibilities include a fuel imbalance, a flap asymmetry, or a bent or mis-rigged component. The absence of vibration does not rule these out.
Immediate actions. At 400 ft you are below a safe manoeuvring height. Fly the aircraft, maintain a positive climb, and do not attempt to troubleshoot at low level. Climb straight ahead to a safe altitude (at least 1,000 ft above the aerodrome, ideally 1,500 ft) and level off. Then check: fuel balance, flap indication, and whether the force is constant or changes with speed and configuration. If the correction required is small and constant, and the aircraft is otherwise controllable, return for a landing. If the force is large, increasing, or accompanied by any other abnormality, land as soon as practicable.
After landing. Do not sign the aircraft back into service on the basis of a 'small' tendency. Refer it back to the maintenance organisation for a rigging check and a duplicate inspection. A persistent out-of-trim condition after control-cable work is a maintenance error until proven otherwise.
2. Explain why the pre-flight feel of the controls was not an adequate check.
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Static versus dynamic. On the ground the ailerons are unloaded and the aircraft is stationary. A cable rigging error of a degree or two produces a control force that is very hard to detect by hand at the wheel, especially when the aircraft is new to you after maintenance and your memory of the 'before' feel is imprecise. The stiffness you noticed could equally have been normal variation, temperature, or expectation bias.
In flight the loads are real. At 50-100 kt the aerodynamic loads on the ailerons are significant, and a small asymmetry becomes a continuous corrective input. That is why the discrepancy only became obvious after rotation. The pre-flight check verifies freedom of movement and correct sense, not symmetry of rigging under load.
Lesson. After any control-system maintenance, the first flight should be treated as a test flight: a cautious climb, a check of control forces and trim in both directions, and a prompt return if anything is asymmetric. The pre-flight is necessary but not sufficient. The correct mental model is that the aircraft has changed and you are the person who will discover how.