Life-Support Reliability Demonstration Test

Test Plan

Target reliability R 99.0%

Confidence level C 90%

True unit reliability (hidden truth) 99.5%

Required test units n

Allowable failures r

Awaiting test campaign…

Live Results

Units tested

0 / 0

Failures so far

Demonstrated reliability

—

Lower conf. bound

—

How it works

Flight hardware for a life-support system (a CO₂ scrubber cartridge, a valve, a filter) is certified with a zero-failure reliability demonstration test: run n identical units through an accelerated environmental stress cycle (thermal-vacuum + vibration), and if r or fewer fail, the hardware is qualified to reliability R at confidence C.

C = 1 - Σ(k=0..r) C(n,k)·(1-R)^k·R^(n-k)

For r = 0 (zero-failure plan):
  n = ceil( ln(1-C) / ln(R) )

Each qual cycle draws a Bernoulli outcome per test unit using the hidden true reliability you set (the unknown real quality of the hardware) — that is what the certification process is trying to estimate without knowing it in advance. The chamber array lights green for a pass, red for a fail, and shakes visibly during its vibration phase.

The demonstrated reliability is the raw pass rate observed so far; the lower confidence bound uses the Clopper–Pearson exact bound at your chosen confidence level — the number regulators actually sign off on, since raw pass rate alone overstates reliability for small sample sizes.

Target reliability / confidence — sets the certification requirement (n, r) via the binomial test-plan formula above.
True unit reliability — the real (unobserved) failure rate of the hardware being qualified; move it below the target to see a qual campaign correctly fail.
Run one qual cycle — tests the next unit in the chamber array and updates the verdict once all n units have been tested.

This is the same statistical logic behind NASA-STD-8729.1 and ECSS-Q-ST-30 hardware qualification: certification is a sample-size problem, not a single pass/fail switch.

Passed unit Failed unit Under test Awaiting test

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.