L-306 International Review of In-Service Surveillance of Composite Propellant Rocket Motors

This report aims to improve understanding of the current approaches for monitoring the ageing of composite-propellant rocket motors (CPRM). A survey was conducted to collect information on current national in-service surveillance (ISS) activities and the uses of the ISS data collected. A total of 22 responses were received, from both government and industry, representing ten member nations and one non-member nation.

Responses indicated that debonding within the rocket motor and propellant hardening are considered to be the two most safety critical ageing phenomena, and respondents identified mechanical properties of the propellant as the main parameters for assessment. Visual inspection is the most common form of non-destructive inspection conducted across the survey respondents, closely followed by radiography. Rocket motor firings, including post-firing inspections, are conducted as part of ISS for the majority of the survey respondents. The inclusion of accelerated ageing as part of ISS of CPRM is fairly common across the respondents; however, ageing conditions vary across organisations, with a strong dependency on the service life requirements of the rocket motor. Data collected through ISS testing is typically compared to analogous data previously collected during ISS, during energetic material qualification, and/or during batch/lot acceptance.

A clear, uniform, set of sentencing criteria for assessing CPRM does not exist: assessment criteria vary between organisations and munition systems.

Recommendations are presented as to possible areas of future work and opportunities for sharing best practices, which may lead to improvements in safety assessments of CPRM. Specific areas include the generation and improvement of ageing algorithms for CPRM by dedicated testing, improved data collection, and sharing ageing models; standardization of test measurements; and provision of the safety limits by the manufacturer to those conducting life assessments.