69-19-04 SLINGSBY: Amdt. 39-841. Applies to Model T.53B Gliders.
To ensure that the glider can be trimmed when being aero-towed, within the next 10 hours' time in service after the effective date of this AD, unless already accomplished, check to determine that the tailplane incidence is 1 degree 50' + 20'. If it is incorrect change the incidence of the tailplane to 1 degree 50' + 20' measured from the aircraft datum in accordance with Slingsby Aircraft Company Ltd., Technical Instruction No. 40, dated July 1969 or later ARB issue or an FAA approved equivalent.
This amendment becomes effective September 15, 1969.