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Mechanical Fault Tree Analysis

Scope and Description

This topic area covers fault tree analysis (FTA) of spacecraft mechanisms. Fault tree analyses provide a graphical, logical representation of the reliability of a system against individual faults. As opposed to a failure mode and effects analysis (FMEA), an FTA is a top-down approach which starts with the higher level system fault and expands downward to identify events or combinations of events that would result in the fault. The logic and events captured in the fault tree can be used to predict the fault probability and identify efficient approaches (e.g., modified designs or operational plans) to reduce the overall probability of a fault. Deployable mechanisms are common in smallsats, and are often custom built for a particular payload. FTA is an intuitive, graphical approach for reliability analysis of these designs.

Resources in this topic area are primarily articles that include FTA case studies and software tools for FTA. Note that FTA is not limited to mechanical systems, so these resources often include electronic and software systems; however, the general approach is consistent and the examples are still useful for mechanical FTA.

Best Practices and Lessons Learned

Last Updated:

Nov. 1, 2021

Compared to failure mode and effects analysis (FMEA), which is a bottom-up approach to reliability analysis, fault tree analysis is less likely to identify all possible initiating faults; however, a basic fault tree analysis is faster and easier to create and can be established earlier in the design process.


Last Updated: Oct. 19, 2021

This these provides detailed information on the programmatic and technical risks associated with student-led ... satellite projects. Section 4.1 introduces and compares various options for failure mode analyses, including fault tree analysis.

Last Updated: Oct. 19, 2021

This paper provides an concise, basic introduction to fault tree analysis (FTA) and the potential value ... it can offer in the design process and during operations for diagnosis of faults. Example fault trees for the HERMES attitude control, communications, and power subsystems are provided in Section 2.

Last Updated: Aug. 26, 2021

This NASA handbook on Fault Tree Analysis (FTA) describes concepts, procedures, tools, and uses for FTA. ... Additionally, it provides detailed guidance on how to implement FTA methods to reduce risk in spacecraft missions.

Last Updated: Aug. 26, 2021

This tool performs probabilistic risk assessments using the Hybrid Causal Logic method. It is arranged ... in three segments: the event sequence diagram, fault tree diagrams, and Bayesian networks. It is currently supported by NASA JPL for system reliability analysis of satellite COTS components.

Last Updated: Oct. 19, 2021

This conference paper presents a fault tree analysis of the DFH-3 satellite solar array. FTA logic is ... used to quantify the reliability of the solar array mechanism, identify the most significant drivers of reliability, and make recommendations for risk mitigation.

Reliability Analysis of SwampSat

Bungo Shiotani

Last Updated: Oct. 19, 2021

This thesis documents the application of reliability analysis techniques to a university cubesat to enable ... identification and mitigation of failure modes. Section 4 documents fault tree analysis of the cubesat, which is use to complement the a failure modes, effects, and criticality analysis (FMECA) by creating fault trees for the most severe failure modes identified in the FMECA.


Software Tool

Last Updated: Oct. 17, 2021

"BlockSim provides a comprehensive platform for system reliability, availability, maintainability and ... related analyses that allows you to model the most complex systems and processes using reliability block diagrams (RBDs), fault tree analysis (FTA), or Markov diagrams."

Last Updated: Oct. 18, 2021

This article discusses the reliability of a non-explosive separation device using Ni-CR wire for small ... satellites. The reliability analysis is performed using a fault tree analysis (FTA) model and the associated risks are categorized and ranked.