Servo transparency

[2][3] The effect, if not promptly recognised by the pilot, can be hazardous as it can lead to partial or total loss of control, which, if encountered at low altitude, could result in impact with terrain.

The maximum force that such servos can impart is set, and depends primarily on the design service pressure delivered by the aircraft's hydraulic system.

[2] However, if a helicopters encounters servo transparency while in a turn towards the blades' retreating side, there is the risk that the bank angle could significantly increase and lead to loss of control, before an unsuspecting pilot has a chance to recognise the phenomenon and take corrective action.

[6]: 41 When encountering servo transparency conditions, pilots are advised to immediately reduce the severity of the manoeuvre by following the controls movements, which allows the collective pitch to decrease naturally, thus lowering the rotor loading.

[8][9] In a widely circulated 2003 service letter on the subject, Eurocopter (now Airbus Helicopters) explains that servo transparency could be regarded as a consequence of the self-limiting structural design of the AS350.