Service Life

Although service life computations have not been used to determine grounding or airframerestrictions, the Air Force has used service life estimates as a planning tool to anticipate when major aircraft structural events can be expected.
A key issue was the structural service life of the C-130 airframes, which was dependent on mission severity, fatigue, and corrosion factors.

A severity factor accounted for the difference between normal civilian flying and military flying (low level, short-field landings, etc.).
Mission profile determined the severity factor, which was averaged over each aircraft's most recent two year history.
This calculation translated airframe clock hours into equivalent airframedamage hours which would indicate the higher aging rate of the military airframes.
On average, active C-130 aircraft were found to be flying approximately 600 hours per year, while ARC C-130E and C-130H aircraft were flying about 375 hours and 450 hours per year, respectively.