Life Limit – 14CFR Part 43.10
– Life-limited part means any part for which a mandatory replacement limit is specified in the type design, the Instructions for Continued Airworthiness, or the maintenance manual. Also, in regards to rotating parts – “An operational service exposure limit characterized by the application of a finite number of flights or flight cycles.”
Life Limited Parts are designated by the manfactuer during the certification of the part
For rotating parts, under FAA guidance material it is equal to the minimum number of flight cycles required to initiate a crack equal to approximately 0.030 inches in length by 0.015 inches in depth. For life-limited pressure-loaded static parts, the life limit may be based on the crack initiation life plus a portion of the residual crack growth life.
Life management. A series of interrelated engineering, manufacturing, and service support activities that ensure that life-limited engine parts are removed from service prior to the development of a hazardous condition.