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

Path	Skill	When to route to it
systems-engineering-safety/arp4754a/systems-planning	ARP4754A systems planning	FDAL/IDAL allocation, certification and development plans
systems-engineering-safety/arp4754a/requirements-traceability	ARP4754A requirements traceability	SRATS to HLR to LLR to code to tests, closure matrix
systems-engineering-safety/arp4754a/requirements-allocation	ARP4754A requirements allocation	allocation to items and functions, allocation coverage, unallocated requirements, double allocation
systems-engineering-safety/arp4754a/validation	ARP4754A validation	validation methods, requirements confirmation, validation scenarios
systems-engineering-safety/arp4761a/safety-assessment	ARP4761A safety assessment	FHA/PSSA/SSA sequence, analysis set selection
systems-engineering-safety/arp4761a/functional-hazard-assessment	ARP4761A functional hazard assessment	failure conditions, severity rating, probability targets, FHA worksheet, A-FHA, S-FHA
systems-engineering-safety/arp4761a/fta-fmea	FTA and FMEA	fault trees, minimal cut sets, failure modes, common cause
systems-engineering-safety/arp4761a/common-cause-analysis	Common cause analysis	common mode failures, zonal analysis, separation, independence
systems-engineering-safety/arp4761a/zonal-safety-analysis	ARP4761A zonal safety analysis	zone identification, zonal hazard severity, separation, containment, zonal hazard checklist, ZSA report
systems-engineering-safety/arp4761a/particular-risk-analysis	Particular risk analysis	single-event risks, rotor burst, bird strike, conditional probability, containment
systems-engineering-safety/arp4761a/operating-support-hazard-analysis	O&SHA	operating and support hazard analysis, maintenance hazards, ground operations, hazard register, risk index
systems-engineering-safety/mbse/systems-engineering	MBSE systems engineering	SysML modeling, function allocation, traceability closure
systems-engineering-safety/mbse/sysml-modeling	SysML modeling	diagram kinds, BDD/IBD, requirement and parametric diagrams, viewpoints, governance
systems-engineering-safety/mbse/state-machine	State machine modeling	SysML state machines, states, transitions, guards, events, reachability, firing trace
systems-engineering-safety/mbse/trade-study-analysis	Trade study analysis	trade study, decision criteria, weighted scoring, Pugh matrix, sensitivity analysis, alternative selection
systems-engineering-safety/arp4761a/markov-analysis	Markov analysis	Markov chain, state probability, transition rate, failure rate, repair rate, availability, MTTF, k-out-of-n
systems-engineering-safety/arp4754a/verification-planning	ARP4754A verification planning	verification methods, test/analysis/demonstration/inspection, verification coverage, derived requirements
systems-engineering-safety/mbse/n2-diagram	N2 interface diagram	N2 diagram, interface matrix, data links, interface count, missing interfaces
systems-engineering-safety/mbse/requirements-modeling	SysML requirements modeling	requirement stereotype, requirements diagram, derive/satisfy/verify links, status roll-up, vague term screening, verifiability
systems-engineering-safety/arp4754a/derived-requirements	ARP4754A derived requirements	derived requirement, derivation rationale, design decision source, implementation constraint, interface resolution, traceability path
systems-engineering-safety/arp4754a/development-assurance-levels	Development assurance levels	FDAL, IDAL, failure condition severity, DAL assignment A-E, independence
systems-engineering-safety/arp4761a/failure-rate-estimation	Failure rate estimation	failure rate, test hours, zero-failure demonstration, chi-square bound, confidence level
systems-engineering-safety/requirements/requirements-elicitation	Requirements elicitation	stakeholder needs, operational scenario, requirements baseline, atomicity, verifiability, weasel words, elicitation log
systems-engineering-safety/certification/certification-basis	Certification basis	certification basis, type certificate, supplemental type certificate, TSO, special conditions, FAR applicability, CS-25, certification program, means of compliance, regulatory path
systems-engineering-safety/arp4761a/preliminary-system-safety-assessment	Preliminary system safety assessment	PSSA, preliminary system safety assessment, safety requirements, FDAL, IDAL, allocation, architecture
systems-engineering-safety/arp4754a/systems-configuration-management	Configuration Management	configuration management, baseline, change control, change request, impact analysis, major change, minor change, safety critical requirement, certification data, interfaces, configuration item, change history, traceability closure.
systems-engineering-safety/arp4761a/reliability-block-diagram	Reliability block diagram	reliability block diagram, RBD, series parallel reliability, k-out-of-n, standby redundancy, MTBF
systems-engineering-safety/certification/means-of-compliance	Means of compliance	means of compliance, MOC-1, MOC-2, MOC-3, MOC-6, compliance matrix, certification item, coverage score
systems-engineering-safety/certification/equivalent-level-of-safety	Equivalent level of safety	ELOS finding, deviation from literal compliance, regulation intent, compensating measure, safety margin, equivalent safety finding
systems-engineering-safety/certification/mmel-development	MMEL development	master minimum equipment list, MMEL, dispatch with inoperative equipment, interval category, O procedure, M maintenance flag, relief verdict
systems-engineering-safety/continued-airworthiness/in-service-safety-assessment	In-service safety assessment	in-service safety assessment, service difficulty report, continued airworthiness, field event rate, observed versus predicted rate, single event rule, service bulletin, airworthiness directive request
systems-engineering-safety/safety-case/goal-structuring-notation	Goal structuring notation	goal structuring notation, GSN, safety argument, safety case, claim decomposition, solution node, away goal, argument validation, support coverage
systems-engineering-safety/continued-airworthiness/msg3-maintenance-analysis	MSG-3 maintenance analysis	MSG-3, maintenance steering group, scheduled maintenance task selection, hidden failure, evident failure, task category, interval determination, maintenance program development
systems-engineering-safety/continued-airworthiness/ica-cmr-ali-classification	ICA/CMR/ALI classification	airworthiness limitation items, ALI, certification maintenance requirements, CMR, airworthiness limitations section, ALS coverage, life-limited part, instructions for continued airworthiness
systems-engineering-safety/continued-airworthiness/airworthiness-directive-compliance	AD compliance	airworthiness directive compliance, directive applicability, affected model and serial range, compliance time remaining, grace band, open due overdue fleet report, directive effectivity
systems-engineering-safety/continued-airworthiness/type-certificate-data-sheet	Type certificate data sheet	type certificate data sheet, TCDS, type design record, approved model list, category airspeed limits, weight block validation, revision diff
systems-engineering-safety/arp4761a/fault-tree-importance-measures	Fault tree importance measures	fault tree importance measures, Birnbaum importance, Fussell-Vesely importance, risk achievement worth, risk reduction worth, basic event ranking, top event sensitivity
systems-engineering-safety/arp4761a/failure-mode-criticality	Failure mode criticality	failure mode criticality, FMECA criticality number, mode ratio, failure effect probability, item criticality, rate based ranking
systems-engineering-safety/arp4761a/beta-factor-analysis	Beta factor analysis	beta factor analysis, common cause fraction, CCF probability, common cause model, redundant channel common cause
systems-engineering-safety/arp4761a/fault-tree-uncertainty-analysis	Fault tree uncertainty analysis	fault tree uncertainty, lognormal error factor, lognormal confidence band, exceedance probability, uncertainty variance share
systems-engineering-safety/arp4761a/ssa-closure	SSA closure	ssa closure, system safety assessment close-out, closure gate, predicted probability margin, requirement closure
systems-engineering-safety/arp4761a/fmes-coverage-analysis	FMES coverage analysis	FMES coverage, FMEA to FHA coverage, uncovered failure condition, orphan row, coverage score
systems-engineering-safety/arp4761a/event-tree-analysis	Event tree analysis	event tree analysis, initiating event, mitigating function, branch path enumeration, end state frequency, dominant sequence
systems-engineering-safety/arp4761a/reliability-growth-analysis	Reliability growth analysis	reliability growth analysis, Duane growth slope, Crow-AMSAA shape beta, current MTBF, projected MTBF, growth verdict
systems-engineering-safety/arp4761a/maintainability-prediction	Maintainability prediction	maintainability prediction, failure rate weighted MTTR, mean time to repair, lognormal repair time percentile, t95 repair time
systems-engineering-safety/arp4761a/fault-tree-quantification	Fault tree quantification	top-event probability from minimal cut sets, rare-event approximation, min-cut upper bound, cut-set truncation
systems-engineering-safety/arp4761a/reliability-allocation	Reliability allocation	failure-rate and MTBF budget flow-down, equal-split and complexity-weighted apportionment, series-sum closure

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.