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Verified the actual PDF cover pages: FMD-91 (ADA259655) and NPRD-91 (ADA242083) carry "© 1991, IIT Research Institute. All Rights Reserved" plus a DoD "distribution unlimited" statement. The distribution statement permits obtaining/reading the document, NOT reproducing its tables in a commercial product — treat like DIN/ISO. The earlier P1 docs wrongly labelled them "public domain" (an unverified research claim). - Correct the licence in fmea_data_sources.go note + mil_std_1629a_fmeca.md + fmd91_nprd_failure_modes.md (read-reference only; tables NOT reproduced). - The bp_iace_fmea_kb collection was deleted from Qdrant (the mislabelled doc removed); methodology docs (MIL-STD/NASA, genuine PD) not re-ingested pending review. The Go methodology module (own scales, MIL-STD-anchored) is unaffected and stays. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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2.2 KiB
FMECA methodology — MIL-STD-1629A (US public domain)
Canonical, citable methodology source for the IACE auto-FMEA. Ingested into the
core RAG collection bp_iace_fmea_kb.
Source
- Source: US DoD — MIL-STD-1629A, Procedures for Performing a Failure Mode, Effects and Criticality Analysis (cancelled 1998, still the de-facto FMECA reference)
- License: US Government work — public domain (17 U.S.C. §105)
- Attribution:
Source: MIL-STD-1629A (US DoD), public domain - Retrieved: 2026-06 · Ref: everyspec / Wikipedia FMECA
Procedure (qualitative + quantitative)
- Define the system, indenture levels and ground rules.
- For each item/function: list failure modes → causes → local / next-higher / end effects.
- Assign a severity category (I–IV, below).
- Quantitative path (when failure-rate data exists): compute the modal
criticality
Cm = λp · α · β · t— λp part failure rate, α failure-mode ratio (fraction of part failures in this mode), β conditional probability the mode causes the analysed effect, t operating time. Item criticalityCr = Σ Cm. - Qualitative path (Task 101, no λ data): assign probability-of-occurrence levels A–E (Frequent → Extremely unlikely) instead of Cm.
- Plot items on a severity × criticality matrix — the open analogue of an action-priority ranking (no copyrighted S×O×D RPN table needed).
Severity categories (MIL-STD-1629A / MIL-STD-882 lineage)
| Cat | Name | Meaning |
|---|---|---|
| I | Catastrophic | May cause death or system loss |
| II | Critical | Severe injury / major damage |
| III | Marginal | Minor injury / minor damage |
| IV | Minor (Negligible) | No injury; unscheduled maintenance/repair |
How used in IACE
- The Cm formula and the severity × criticality matrix are the public-domain
criticality backbone (
CriticalityCmin fmea_data_sources.go). - λp/α are informed by FMD-91/NPRD-91 as a READ reference only — those are © IITRI (All Rights Reserved), not reproduced; β and t from the project context.
- Severity resolves through the linked EN ISO 12100 hazard (safety-FMEA bridge).
No AIAG-VDA / SAE J1739 / IEC 60812 content is reproduced.