From RR 250 MM  

Life Limited Parts
Chapter 05-10-00 contains FAA approved life limitations for those engine parts that are life limited.
Life limits of parts are based on total hours or total cycles, which ever occurs first.

Operating hours with respect to maintenance records means the time from the moment an aircraft leaves the surface of the earth until it touches at the next point of landing.

A cycle is defined as a start or start attempt. The operator is assisted in maintaining a cycle count by means of an engine furnished counter which will record the number of times the ignition exciter is energized. (It is considered that the number of times the ignition exciter is energized and lightoff does not occur is negligible.)