Zie: http://ad.easa.europa.eu/ad/2012-0181Corroded and cracked elevator control road in the vertical fin on a Grob G 109B
powered sailplane has been reported.
The technical investigation revealed that water had soaked into the elevator
control rod through a control bore hole and resulted in corrosion damage and,
in case of water freeze between the external control rod and the internal mass
balance, in crack of the elevator control rod in the vertical fin.
This condition, if not detected and corrected, could lead to failure of the elevator
control rod, possibly resulting in loss of control of the sailplane.
To address this unsafe condition, Grob Aircraft AG published Service Bulletin
(MSB) 817-64 providing instructions for elevator control rod inspection and
replacement.
For the reasons described above, this AD requires accomplishment of
inspections of the elevator control rod in the vertical fin and, depending on
finding, its replacement with a serviceable part, as well as a revision of powered
sailplane Aircraft Maintenance Manual (AMM).
