Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Lockheed Model 1329-23 and 1329-25 series airplanes. This proposal would require revising the Airplane Flight Manual (AFM) to include requirements for activation of the airframe pneumatic deicing boots. This proposal is prompted by reports of inflight incidents and an accident that occurred in icing conditions where the airframe pneumatic deicing boots were not activated. The actions specified by the proposed AD are intended to ensure that flightcrews activate the pneumatic wing and tail deicing boots at the first signs of ice accumulation. This action will prevent reduced controllability of the aircraft due to adverse aerodynamic effects of ice adhering to the airplane prior to the first deicing cycle.