Abstract : �The objective of this research is to evaluate and
improve the mechanical system of MLRP’s failure modes. At first, the analysis of possible failure modes and their effects for individual designed product’s system and sub-system is carried out. The potential causes of failure as well as current design control are also identified. Each design failure mode is rated for its severity of effect,
likely failure rates over design life, and likelihood of detection by current design control, respectively. Once all failure modes are prioritized by corresponding Risk Priority Number (RPN), the failure modes having RPN more than 100 are classified as major failure and thus selected for correction improvement. Recommended Possible
Action (RPA) may be considered for overcoming those particularly major failures. Finally, we re-evaluate above procedure by currently updating system and sub-system of product and repeating RPN calculation to obtain Appropriated Recommended Possible Action (ARPA). The RPN rating lower than 100 is categorized as ARPA.
The research results show that the most vital concerned subsystem is launcher pod (40.5%). The major failure which was prioritized by RPN is (1) Damaged launcher tube caused by improper selection of material, (2) Rocket falls out from the guided rail caused by designed rail size failed to hold guided knob, (3) Peeled guided
rail inside-tube caused by low cohesive force between them, (4)Distortion of launcher tube caused by unable to withstand torque load from rocket spinning not well select from the uncertainty of the thermal load and (5) Damaged guided rail during firing caused by corrosion problem. The result noticeably indicated that the diminished RPN can be achieved by paying more attention on structural design and correctly selecting proper material. Moreover,
the finite element method should be applied during sub-system verification, and live firing test of the prototyping platform will be used as sub-system validation

Author :�Phermsak S., Tosapolporn P. Kraisunate H.