FAILURE INVESTIGATION OF PYRO CARTRIDGE FOR DEPLOYMENT OF EMPTY FUEL TANK

This article explains about failure investigation of a pyro cartridge that fails in the proof trials before sentencing lot clearance for the acceptance of hardware. Blow holes, bulging, and cracks around cannullering areas of a pyro-cartridge case were observed. The case was manufactured from brass material. The visual examination, chemical analysis, micro-examination, thickness measurement, and hardness measurement of the pyro-cartridge case was undertaken. Failure investigation plays an important role in the design and development cycle of a pyro cartridge. The novelty in this research is that it was attempted to carry out the failure investigation of a pyro cartridge. This cartridge plays a crucial role in safe and rapid deployment of the fuel tank in an emergency situation from a fighter aircraft. This research paper focuses on failure investigation of a pyro cartridge for dropping empty fuel tank after exhausting of fuel from the fighter aircraft. By applying failure analysis in a systematic way, it is absolutely possible to identify the underlying failure reasons of the pyro cartridge and enhance safety measures to reduce catastrophic failures during empty fuel-tank deployment. After detailed investigation, the major outcomes obtained from the failure analysis highlighted that failures occurred due to higher hardness than specified limits, i.e., 110 VPN at 5 kg load. The other reasons for failures were traditional gas flame annealing that gives uneven heating and cooling, and cartridge case thickness observed low against specified thickness, 0.5 + 0.1 mm. This paper provides investigation of the failure modes of pyro cartridges that explores the methodologies for failure investigation.