pdf GFA AD 688 Issue 1 Popular
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GFA AD 688 Issue 1.pdf
CORROSION OF CONTROLS AND FITTINGS IN AFT FUSELAGE
An owner of a Schempp-Hirth aircraft identified corrosion on the aft end of the elevator pushrod in the fuselage. On removal of the pushrod, the aft end of the rod broke off completely. Other signs of corrosion were seen on nearby fittings. The cause is likely to be urine from the relief tube or water from water ballast flowing along the underside of the fuselage and being drawn back into the fuselage through the drain hole in front of the tail wheel. The area is difficult to inspect and was found by looking down the fin through the slot for the vertical pushrod in the bottom fin rib. This Airworthiness Directive mandates a visual inspection of all metal pushrods and fittings in the bottom of the fin and aft end of the fuselage for corrosion.