Reliability, Availability, Maintainability and Safety (RAMS) Consulting

Failure rate calculation is quite simple and straightforward for systems with no redundancies and components with a constant failure rate: one can simply sum the components’ failure rates.
In these cases, the Mean Time Between Failures (MTBF) is also easily calculated:


MTBF=1/Failure Rate


However, systems with fault tolerance, redundancies, and components that age (increasing failure rate in time) are harder to model. Additional details that may affect the system reliability model are: operation profile, spare parts logistics, and scheduled inspections and maintenance.


We at BQR have vast experience with reliability modeling of complex systems, using our software tools:

  • Reliability Block Diagram (basic, networks, Markov chain models)
  • Fault Tree Analysis which supports common causes and nested common causes
  • apmOptimizer


BQR also performs Monte Carlo simulations that can be adapted to fit special cases.

BQR’s advanced tools for reliability modelling:

Reliability Block Diagram (Basic)

Used for modelling systems with standard block dependencies (Serial, Parallel, K out of N and Stand-By), with various repair policies (Hot, Cold), and failure distributions.

RAM analysis - Reliability Block Diagram Software
RAM analysis - Reliability Block Diagram Software

Reliability Block Diagram (Network)

Used for modelling systems with nonstandard block dependencies.

RAM analysis - Reliability Block Diagram Software
Network Reliability Block Diagram

Monte Carlo Simulations

Used for plotting the point availability and other time dependent parameters.

Reliability Block Diagram Software - Monte Carlo simulation
Monte Carlo simulation results for two pumps operating in standby model

Markov Chains

Used for modelling load sharing, shared spare parts, and other systems where component failure rate depends on other components.

Reliability Block Diagram Software - Markov Models
Markov model

Fault Tree Analysis

Used mostly for safety analysis, supporting nested common causes.

FTA traditional view
FTA traditional view

Modelling systems with complex logistics

Industry 4.0 IIoT systems