How do I calculate the mean time between failure of an RF system from component level reliability data?

The system-level MTBF is calculated from the individual component failure rates using the series reliability model (assuming any single component failure causes a system failure): (1) Series reliability model: for a system with N components, each with failure rate λ_i (failures per hour): system failure rate: λ_system = Σ λ_i (sum of all component failure rates). System MTBF = 1 / λ_system. This assumes: all components must work for the system to function (series model), component failures are independent (no common-cause failures), and failure rates are constant (exponential distribution: the bathtub curve is in the flat "useful life" region). (2) Component failure rate sources: MIL-HDBK-217F: provides base failure rates for electronic components, adjusted by stress factors (temperature, voltage, environment). Example base failure rates (at 25°C, ground benign): resistor (film): λ = 0.001 × 10^-6 per hour (1 FIT). Capacitor (ceramic): λ = 0.01 × 10^-6 per hour (10 FIT). MMIC amplifier: λ = 0.1-1.0 × 10^-6 per hour (100-1000 FIT). Connector (RF): λ = 0.05 × 10^-6 per hour (50 FIT). Telcordia SR-332: used for telecom reliability prediction (generally more optimistic than MIL-HDBK-217F). FIDES: European reliability prediction standard (newer, more nuanced than MIL-HDBK-217F). (3) Environmental stress factors: the base failure rate is multiplied by stress factors for: temperature (π_T): increases exponentially with junction temperature (Arrhenius model). Electrical stress (π_S): increases with the ratio of applied voltage/power to the rated value. Environment (π_E): multiplier for the operating environment: ground benign (laboratory): π_E = 1.0, ground fixed (outdoor shelter): π_E = 4.0, airborne inhabited (cargo bay): π_E = 8.0, and missile launch: π_E = 120. (4) Example: RF receiver with 50 components: 2 MMIC amplifiers: λ = 2 × 500 FIT = 1000 FIT. 1 mixer: λ = 500 FIT. 20 capacitors: λ = 20 × 10 FIT = 200 FIT. 15 resistors: λ = 15 × 1 FIT = 15 FIT. 5 connectors: λ = 5 × 50 FIT = 250 FIT. 4 filters: λ = 4 × 100 FIT = 400 FIT. 3 ICs: λ = 3 × 200 FIT = 600 FIT. Total: λ_system = 2965 FIT = 2.965 × 10^-6 per hour. MTBF = 1 / 2.965 × 10^-6 = 337,268 hours ≈ 38.5 years. Apply environment factor (airborne inhabited, π_E = 8): λ_adjusted = 2965 × 8 = 23,720 FIT. MTBF_airborne = 42,158 hours ≈ 4.8 years.