The US Navy has extended the fatigue life of its 220 Northrop Grumman F-14 Tomcats by re-evaluating the original structural analysis and service life projections of the aircraft. This will ensure that the fighter has a substantial number of available flight hours left after the type is retired from 2003.

A $10 million study by US Naval Air Systems Command has resulted in a 26% increase for the F-14A life and 16% for the later B/D versions. "As a result of the new information, we saved $268 million that would have had to be spent on time compliance requirements [TCRs] and overhauls," says Jim Blackman, F-14 deputy programme manager.

The flight test and fatigue test revalidation were prompted by an anticipated 22% shortfall in the aircraft's fatigue life, based on F-14 data analysed in 1997.

This would have required a structural modification programme to keep the aircraft operational beyond 1999 until the F-14A's planned retirement.

An F-14 was instrumented and test flown through the flight envelope to collect new information on stress in critical areas of the airframe. The testing also took into consideration expansion of the F-14's operational role from being a dedicated air superiority fighter to including strike and reconnaissance missions.

According to Blackman, the F-14A could remain in service for another five years without modification, if needed. Implementing TCRs would have added another three years. The USN's 80 General Electric F110-powered F-14Bs and 50 F-14Ds will have an estimated two years of life remaining after the two versions are retired in 2006 and 2007, respectively.

Source: Flight International