Technical report | Retrogression and Re-Ageing In-Service Demonstrator Trial: Stage II Component Test Report

Abstract 

Retrogression and Re-ageing (RRA) technology is a two stage heat treatment of 7075-T6 aluminium alloy used to improve corrosion resistance while retaining MIL-HDBK-5J structural properties. This report assesses the compliance of the industrial trial, conducted at Boeing Australia Component Repairs (BACR) on 21st April 2009, with the requirements of the compliance matrices in the Stage II Design Development Plan and, by extension, the Stage II Process Specification for RRA. Of the 35 items in these matrices 31 were given recommended ratings of 'Compliant' while the remaining four received recommended ratings of 'Non-Compliant (Acceptable)'.

Executive Summary

Retrogression and Re-ageing (RRA) technology is a two stage heat treatment of 7075-T6 aluminium alloy used to improve corrosion resistance while retaining MIL-HDBK-5J structural properties.

The certification and acceptance of the RRA technology for application to Australian Defence Force (ADF) aircraft has been undertaken in sequential stages. The first stage was the qualification of the RRA technology under laboratory conditions. The second stage consisted primarily of an industrial trial of the technology on a real aircraft component. The third and final stage deals with the practical issues of transitioning RRA onto ADF aircraft.

An industrial trial of the RRA heat treatment on a C-130 Hercules component was conducted at Boeing Australia Component Repairs (BACR) on 21st April 2009. This report assesses the compliance of this industrial trial with the requirements of the compliance matrices in the Stage II Design Development Plan and, by extension, the Stage II Process Specification for RRA. The Stage II Process Specification proved to be sufficient to conduct an industrial heat treatment satisfying the great majority of the compliance items from the compliance matrices. Of the 35 items in these matrices 31 were given recommended ratings of 'Compliant' while the remaining four received recommended ratings of 'Non-Compliant (Acceptable)'.This report concludes with a set of recommendations for updating the Process Specification. These will be incorporated into the Process Specification during the third and final stage of RRA Certification.