Embraer

14 CFR § 39.5 clearly states that an airworthiness directive is issued when an unsafe condition exists in a product and this condition is likely to exist or develop in other products of the same type design. It is important to emphasize that the missing aileron cable guard pin was discovered during a normal C check of an EMB-145 defense aircraft, which is an EMB-145 LR model modified according to Brazilian STC 2003S08-01, operated by the Hellenic Air Force. There is no field report of any event caused by the missing pin. As soon as the problem was identified Embraer performed a test to check the aileron system behavior without the same guard pin in a production aircraft (S/N 145933). This test was made on ground in a much more severe condition, with the tension of the aileron control cables reduced to approximately 5 lbf, when the normal tension would be 110 lbf @ 25 ºC (77 ºF). The aileron system was cycled several times and it was verified that the cables remained in their normal path and the system operated normally. It is not clear that the lack of guard pins leads directly to the aileron jamming but even in the Remote event of having the aileron system jamming in one side, it is possible to disconnect the aileron system and safely operate the aircraft by using the free side. This event is classified as Minor by the system safety assessment. Even in the Extremely Improbable event of having the aileron system jamming in both sides, the aircraft could also be controlled using rudder and differential thrust. This event is classified as Hazardous by the system safety assessment. Based on the information above, Embraer proposes to withdraw this NPRM since there is no unsafe condition caused by the missing aileron cable guard pins.