version: "1.0.0" name: systems-engineering-safety description: "Use when a task concerns aircraft or system-level engineering and safety assurance: guide the router to the systems-engineering-safety pack, covering ARP4754A systems-planning, requirements-traceability, requirements-allocation, verification-planning, and validation, ARP4761A safety-assessment, fta-fmea, common-cause-analysis, particular-risk-analysis, operating-support-hazard-analysis, and markov-analysis, and MBSE systems-engineering, sysml-modeling, state-machine, n2-diagram, and trade-study-analysis. This pack is the systems-level spine above item-level software and hardware assurance. Trigger: systems engineering, systems safety, ARP4754A, ARP4761A, safety assessment, fault tree, FMEA, common cause, particular risk, rotor burst, traceability, validation, allocation, verification planning, O&SHA, state machine, reachability, MBSE, SysML, N2 diagram, interface matrix, FDAL, IDAL, FHA, PSSA, SSA, trade study, Pugh matrix, Markov analysis, availability, MTTF." license: Apache-2.0 compliance: STANDARDS-REF standards:

• id: arp4754a

reference-only: true

• id: arp4761a

reference-only: true gated: false domain: systems-engineering-safety pack: systems-engineering-safety compatibility: "agentskills.io SKILL.md; router/entry point for the systems-engineering-safety domain pack" metadata: domain: systems-engineering-safety tags: [] version: 0.1.0 author: Aero Agent Skills

Systems engineering and safety domain pack (router)

Route here when the task is aircraft or system-level engineering, safety assessment, or model-based systems engineering.

Domain

Systems engineering and safety: development planning and development assurance (ARP4754A), requirements traceability and validation, the safety assessment process (ARP4761A) with fault tree and FMEA analyses, common cause analysis, particular risk analysis, and model-based systems engineering (SysML, digital thread).

Revision note: ARP4754B (2023) supersedes ARP4754A; this pack keys to ARP4754A as the certification-baseline revision (FAA AC 20-174 cites A); see standards-map.yaml arp4754a.revision_decision.

Sub-skills in this pack

Routing guidance

• Development assurance and planning questions route to the ARP4754A

systems-planning sub-skill.

• Traceability and closure questions route to the ARP4754A

requirements-traceability sub-skill; allocating requirements to items and functions, all- Configuration management questions route to the arp4754a configuration-management sub-skill. ocation coverage, and unallocated requirements route to the requirements-allocation sub-skill; validation methods and confirmation questions route to the validation sub-skill.

• Safety assessment questions (severity, FHA/PSSA/SSA, analysis set)

route to the ARP4761A safety-assessment sub-skill.

• Functional hazard assessment questions (failure condition

identification, severity rating into the five categories, probability target mapping, FHA worksheet rows, A-FHA, S-FHA) route to the ARP4761A functional-hazard-assessment sub-skill; the FHA/PSSA/SSA sequence and analysis set selection stay with the safety-assessment sub-skill.

• Fault tree, FMEA, and cut-set questions route to the fta-fmea

sub-skill; common mode and zonal independence questions route to the common-cause-analysis sub-skill.

• Single-event hazard questions (rotor burst, bird strike, tire

burst, fire, conditional probability, containment) route to the particular-risk-analysis sub-skill.

• Zonal safety analysis questions (zone identification, zonal hazard

severity classification, separation and containment verdicts, zonal hazard checklist completeness, ZSA report) route to the zonal-safety-analysis sub-skill; common mode failures and analysis set completeness questions route to the common-cause-analysis sub-skill.

• Operating and support hazard questions (maintenance tasks, ground

operations, hazard register, risk index, acceptability) route to the operating-support-hazard-analysis sub-skill.

• Modeling and digital-thread questions route to the MBSE

sub-skills: system-level engineering to systems-engineering, diagram-specific modeling to sysml-modeling, and state machines with transitions, guards, events, and reachability to state-machine.

• Trade study and alternative-selection questions (decision criteria

weights, Pugh matrix, sensitivity analysis) route to the trade-study-analysis sub-skill.

• Item-level software or hardware questions route to the avionics pack.

• Markov chain, availability, MTTF, and transition rate questions route to the ARP4761A markov-analysis sub-skill.
• Verification method, verification coverage, and derived-requirement verification questions route to the ARP4754A verification-planning sub-skill.
• N2 diagram and interface matrix questions route to the MBSE n2-diagram sub-skill.
• SysML requirement modeling questions (requirement stereotype attributes, derive/satisfy/verify links, status roll-up, vague term screening, verifiability, atomicity) route to the MBSE requirements-modeling sub-skill.
• Derived requirement classification, derivation rationale, design decision and implementation constraint sources, and derived-requirement traceability questions route to the ARP4754A derived-requirements sub-skill.
• FDAL and IDAL assignment, failure condition severity to DAL mapping, and independence questions route to the ARP4754A development-assurance-levels sub-skill.
• Failure-rate estimation and demonstration from test or service data, zero-failure testing, and chi-square confidence bounds route to the ARP4761A failure-rate-estimation sub-skill.
• Stakeholder needs capture, operational scenarios, elicitation log, and requirement statement quality (atomicity, verifiability, weasel words) questions route to the requirements requirements-elicitation sub-skill.
• Certification regulation applicability, special condition determination, and TC, STC, and TSO path selection route to the certification certification-basis sub-skill.
• PSSA derivation of safety requirements from FHA outcomes, FDAL/IDAL allocation, and quantitative safety target allocation across the architecture routes to the arp4761a preliminary-system-safety-assessment sub-skill.
• MSG-3 scheduled maintenance task selection and hidden-failure exposure questions route to the continued-airworthiness msg3-maintenance-analysis sub-skill.
• top-event probability from minimal cut sets, rare-event approximation, min-cut upper bound, cut-set truncation questions route to the arp4761a fault-tree-quantification sub-skill.
• failure-rate and MTBF budget flow-down, equal-split and complexity-weighted apportionment, series-sum closure questions route to the arp4761a reliability-allocation sub-skill.

Install

To install only this pack, copy or symlink each leaf folder above into your host's skills directory (see README Install for per-host commands).

• RBD series parallel and redundancy reliability questions route to the arp4761a reliability-block-diagram sub-skill.
• Per-certification-item means-of-compliance assignment and matrix coverage questions route to the certification means-of-compliance sub-skill.
• Equivalent-level-of-safety questions (deviation from literal compliance with a regulation, compensating measures, safety margin to the rule intent) route to the certification equivalent-level-of-safety sub-skill.
• MMEL proposal questions (master minimum equipment list, dispatch with an item inoperative, interval category, O and M flags) route to the certification mmel-development sub-skill.
• In-service and continued-airworthiness questions (service difficulty reports, field event rate versus the SSA prediction, service bulletin or AD request) route to the continued-airworthiness in-service-safety-assessment sub-skill.
• GSN safety argument questions (claim decomposition, strategy and solution evidence nodes, away-goal justification, support coverage) route to the safety-case goal-structuring-notation sub-skill.
• Airworthiness-limitation and certification-maintenance-requirement questions (ALI/CMR classification, ALS coverage, life-limited part interval compliance) route to the continued-airworthiness ica-cmr-ali-classification sub-skill.

• AD compliance questions (directive applicability by affected model and serial range, compliance-time remaining in flight cycles, flight hours or calendar months, open due overdue status against the grace band, fleet compliance report) route to the continued-airworthiness airworthiness-directive-compliance sub-skill.
• Type-certificate-data-sheet questions (TCDS section compilation, weight block and category airspeed-limit validation, revision diff for TC amendment or STC review) route to the continued-airworthiness type-certificate-data-sheet sub-skill.
• Fault-tree basic-event ranking questions (Birnbaum and Fussell-Vesely importance, risk-achievement-worth and risk-reduction-worth from the minimal cut sets, dominance thresholds) route to the arp4761a fault-tree-importance-measures sub-skill.
• Rate-based failure-mode criticality questions (FMECA criticality number from the mode ratio and the failure-effect probability over an operating time, item criticality ranking for maintenance and redesign prioritization) route to the arp4761a failure-mode-criticality sub-skill.
• Common-cause quantification questions (beta-factor rate split into the independent and the shared common-cause fraction, dual-channel CCF probability, enhancement over the independence-only assumption) route to the arp4761a beta-factor-analysis sub-skill.

• Fault-tree uncertainty questions (lognormal error-factor propagation to a probability band around the top event, exceedance against a target, per-event uncertainty variance shares) route to the arp4761a fault-tree-uncertainty-analysis sub-skill.

• System safety assessment close-out questions (post-implementation verdict rollup by severity, meet-versus-target margins, open-condition and open-requirement lists, closure gate) route to the arp4761a ssa-closure sub-skill.

• FMES coverage questions (FMEA-row to FHA-failure-condition coverage, uncovered failure conditions, orphan FMEA rows, coverage score) route to the arp4761a fmes-coverage-analysis sub-skill.

• Event-tree questions (forward branching from an initiating event through mitigating-function successes and failures, end-state frequency rollup, dominant-sequence screening against severity targets) route to the arp4761a event-tree-analysis sub-skill.
• Reliability-growth questions (Duane log-log growth slope, Crow-AMSAA power-law process shape by MLE, improving or degrading verdict, current and projected MTBF) route to the arp4761a reliability-growth-analysis sub-skill.
• Maintainability-prediction questions (failure-rate-weighted MTTR rollup, lognormal repair-time t50 and t95 percentiles, verdict against a maximum-repair-time requirement) route to the arp4761a maintainability-prediction sub-skill.