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System Safety Analysis(SSA) for eVTOL aircraft

Aim of SSA is to ensure a safe environment during the all flight phases by proactively identifying risks due to system failures. The identified risks are then to be mitigated by employing suitable system architectural changes and safety analyses involving means of rigorous compliance methods as per FAA/EASA/ARP guidelines.

Towards this safety critical task, following aspects need to be addressed during Design and and development of eVTOL aircraft.

  1. Identification of eVTOL aircraft Faults & Failures, associated severities (Catastrophic, hazardous, major and minor) along with likelihood of their occurrence.

  1. Consider different types of Redundancy Mechanisms; Static, Dynamic and Hybrid types involving TMR, NMR, Duplex, Pair and Spare, Self Checking pairs, Command Monitor systems, Self Purging & SIFT. Formulate Reliability equations for the chosen types of redundant Systems for loss of function and inadvertent operation. Finalize redundant system architectures in an iterative manner and show if the finally chosen system architecture is Fail-op and or Fail-safe under the failure conditions, as per the derived safety requirements. .

  1. Seldom does a single hazard cause an accident. Usually, combination of initiating hazards, contributory hazards coinciding with unhealthy system state of aircraft could lead to harmful event or catastrophe. Conducting Integrated System Hazard Analysis (ISHA) could avert such situations. ISHA involves logical combining of several hazard analyses leading to undesirable event during all flight phases.

  1. Safety Order of Precedences (SOP) comprising Design for Minimum Risk, Implementing Safety measures, Providing of Warning and Alert mechanisms to pilots and Firming up of Operating Procedures and required training to flight crew and maintenance team.

  1. Conduct Functional Hazard Analysis(FHA) at Aircraft level (for Aviate, Navigate, Communicate and Transport functions), System level FHA, Preliminary System Safety Analysis(PSSA), Fault Tree Analysis, introduce Derived Safety Requirements in the initial design phase.

  1. During the development process, conduct System Safety Analysis (SSA) including FMEA and revised System level FTA to Verify that the implemented system satisfies the derived safety requirements. Then proceed with Means of Compliance leading to Certification and airworthiness.

We list the EASA eVTOL Rule for future detailed analysis. For further inquiry, please contact us : contact@aiflyllc.com