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Gfa 023an

AIRWORTHINESS SAFETY - CABLE TESION IN CONTROL SYSTEMS / UNSECURED BALLAST

A recent accident involving an ES-52 Mk3 Kookaburra highlights the necessity to continue teaching things which are generally regarded as common knowledge. Twenty years or more ago, people involved in gliding were very much aware of the necessity of maintaining correct cable tension in the control systems of their gliders, however, with the event of push rod control systems, much more of this law is becoming forgotten or neglected. The ES 52 Kookaburra has a control system typical of the older generation of gliders. The ES 52 has relatively large chord aileron which are not mass balanced but years of operation has shown with correct tensioned control cables the aircraft is not prone to aileron flutter. Ballast weight is subject to the same acceleration forces as every other item in the glider, the securing means for the ballast must therefore be adequate to resist these forces. Ballast cushions must be secured, usually to the lap strap attachment points for the safety harness, and the securing straps must be adequate to restrain at least eight times the weight of the ballast cushion since if there is any slack in the straps they will not only need to hold the ballast in place but to withstand the impact of stopping relative motion arising from the slack.