Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Burkhart GROB Luft-und Raumfahrt GmbH (Grob) Model G 109B gliders. The proposed AD would require inspecting the elevator and trim tab for water and to assure that the necessary drain holes are installed and that the existing drain holes are open. The proposed AD would also require drilling any necessary drain holes and opening any existing drain holes that are closed; and, if a significant amount of water (more than \1/2\ liter) is found in the elevator, assuring that the glider's residual momentum and center of gravity (C.G.) are within the limits specified in the flight manual, and adjusting the residual momentum and C.G., as needed. The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Germany. The actions specified by the proposed AD are intended to prevent water from penetrating the elevator and trim tab because of inadequate drainage, which could result in a delaminated elevator and trim tab structure with consequent elevator imbalance and flutter.