73-13-05: Aileron

73-13-05 SLINGSBY: Amdt. 39-1672. Applies to Model Glasflugel T.59.D "Kestrel" gliders. NOTE: This AD does not apply to Glasflugel manufactured "Kestrel" Model gliders. To prevent possible wing flutter due to aileron unbalance, accomplish the following, unless already accomplished: (a) Within the next 10 hours' time in service after the effective date of this AD, remove the ailerons from the glider and measure the aileron mass balance hinge Moment in accordance with Section 1 of Slingsby Sailplanes Technical Instructions No. 54, Issue 2, dated February 1973, or an FAA-approved equivalent. (b) If during the inspection required by paragraph (a), it is found that, either the average balance hinge moment of both ailerons exceeds 8.5 lb.-ins. or the balance hinge moment of either aileron exceeds 9.5 lb.-ins., before further flight, install balance weight on the leading edge of both ailerons in accordance with Section 2 of Slingsby Sailplane Technical Instructions No. 54,Issue 2, dated February 1973, or an FAA-approved equivalent such that the balance hinge moment of each aileron does not exceed 8.0 lb.-ins. This amendment is effective upon publication in the Federal Register as to all persons except those persons to whom it was made immediately effective upon receipt of the airmail letter dated May 21, 1973, which contained this amendment.