The project

There are several distinct areas that are impacted by the extended life evaluation, Structural evaluation (which includes wear, corrosion and fatigue), in-service evaluation (monitoring trends in in-service aircraft) and systems review.  It is this latter area that WEC has had significant involvement with two commercial aircraft Original Equipment Manufacturers (OEMs).

The review of systems sensitive to life extension is defined by:

• Maintenance actions listed in the Maintenance Review Board Report (MRBR), where based on the original Design Service Goal (DSG), require revalidation via a system specific analysis. The revalidation requires review of the original safety analysis, considering the effects of the change to the DSG, specifically with respect to critical failures and any significant events that contribute to these.
• Validation of the Safety analysis against the impact of extended service life. Validation requires support of the suppliers to revalidate their failure data, alternatively the OEM can provide a failure degradation analysis which informs which items are not suitable for life extension.  Any items that could fail more regularly when operated beyond the original DSG, due to degradation in predicted failure probability, need to be identified and the necessity for replacement established in order to maintain the airworthiness of the aircraft.