I 25.4 Reliability requirements

(See CS 25.1309 and AMC 25.1309)

(a)The occurrence of an ATTCS system failure or a combination of failures in the ATTCS system during the critical time interval which –

(1)Prevents the insertion of the required thrust or power, must be shown to be Improbable;

(2)Results in a significant loss or reduction in thrust or power, must be shown to be Extremely Improbable.

(b)The concurrent existence of an ATTCS system failure and an engine failure during the critical time interval must be shown to be Extremely Improbable.

(c)The inadvertent operation of the ATTCS system must be shown either to be Remote or to have no more than a minor effect.