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MISCELLANEOUS REPORTED DEFECTS - IS-28B2

1. Ball coupling failure- One reported incident of a ball snapping in the thread just below the head caused loss of divebrakes control during a pilots pre-flight check 2. Wing root locating pins/cracks- Badly machined wing root locating pins have appeared to be cracked. Under magnification and dye check proven to be scores or scratches. If the scoring extends into the radius area at the root of the pin, cracking may develop with time. Pins should be checked at Form 2 inspections. 3. Push rod bending/cracking- Most IS-28B2 end up with a short push rod linking the aileron to the bellcrank measuring 95mm with the ailerons moving through their correct travel. Bending will occur if aileron leading edge is not relieved after adjustment of push rods on some gliders. 4. Rigging of divebrake and wheel brake- An accident involving an overshoot highlighted the possibility of rigging the wheel brake such that it restricts the divebrake travel excessively. (Not all IS-28s have interconnection). The divebrake extension can be restricted 50 mm to achieve good wheel brake operation with some loss of dive brake effectiveness. 5. Poor turnbuckle fork manufacture- A turnbuckle fork was removed from a control cable because of 'necking' of the shaft during manufacture.