Claude Skills by ashfordeOU

Use when you must compute the multiaxial yield margin of an isotropic metal part: evaluate the von Mises equivalent stress in plane stress sqrt(sx^2 - sx*sy + sy^2 + 3*txy^2) and in full 3D, resolve the plane-stress principal stresses from the Mohr circle, compute the Tresca equivalent stress as the maximum principal stress difference including the zero out-of-plane principal, compute the yield margin yield/equivalent - 1, run the von Mises combined bending-plus-torsion margin for a shaft sec...

Use when you must build the elastic-plastic stress-strain response of a metallic material with the Ramberg-Osgood three-parameter model: compute the total strain at a given stress with strain = stress/E + 0.002*(stress/sigma_0.2)^n, invert the implicit equation by bisection for the stress at a required total strain, and derive the plastic strain, secant modulus, and tangent modulus along the curve. Produces the stress-strain curve points and stiffness values used in metallic structural analys...

Use when you must compute the thermal buckling of restrained aerospace structure from a temperature rise: the elastic buckling stress of a uniformly compressed flat plate, the compressive stress built by a constrained temperature change under uniaxial or biaxial restraint, the critical-temperature-rise that drives a skin panel to its buckling stress, and the critical-temperature-rise of an Euler column between rigid supports. Produces the buckling stress, the compressive stress at a given ris...

Use when a structural member, bonded joint or skin panel is restrained against thermal expansion and must be assessed for thermal load in a stdlib-only environment without FEA software. Compute thermal stress and strain in aerospace structures from a constrained temperature change: free thermal strain alpha*dT, fully constrained thermal stress sigma = E*alpha*dT when free expansion is blocked, the bimetallic strip curvature and per-layer thermal stress balance, and the critical temperature ri...

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-stu...

Use when you must identify, classify, and manage derived requirements per ARP4754A: decide whether a requirement is derived or allocated from its traceability fields, list the required rationale fields (design decision, implementation constraint, interface resolution, architectural choice, environmental assumption) plus the derivation rationale and impact analysis, and run the validation checklist before the requirement enters the requirements baseline. Derived requirements are not directly t...

Use when you must assign development assurance levels per ARP4754A development assurance: rate the failure condition severity into catastrophic, hazardous, major, minor, and no safety effect, map the severity onto the DAL scale A through E, assign the FDAL to each function and the IDAL to each item, and check that no item DAL is lower than its function DAL. Independence between redundant items is evaluated as the alternative to raising the item DAL, and the ARP4761A FHA severity rating feeds ...

Use when you must allocate system requirements to items and functions per ARP4754A development planning: assign each system requirement to a design item or function, check the allocation coverage to find the unallocated requirements, detect a requirement allocated to more than one item, and group the allocated requirements per item for the item development handoff. Produces the allocation register, the unallocated list, and the double allocation verdict that gate the handoff of requirements t...

Use when planning or auditing requirements traceability per ARP4754A: determine closure status across SRATS, high-level requirements (HLR), low-level requirements (LLR), code, and test levels, list traceability gaps for a level, flag derived requirements, and compute the verified-closure ratio of the trace matrix. Bidirectional closure (each level traces down and back up) and open verification items drive the closed/open verdict; all logic is deterministic, offline stdlib. Trigger: traceabili...

Use when managing configuration of aircraft system requirements and design data per ARP4754A: identify configuration items (requirements, design data, verification data, analysis), create and version baselines, run change control (change request, impact analysis, minor vs major classification, approval, implementation, verification), check traceability closure (every requirement mapped to a design element and a verification method, every derived requirement sourced), and record change history...

Use when you must plan aircraft and system development per ARP4754A: allocate FDAL to functions and IDAL to items from failure-condition severity, scope the certification plan and system development plan, and interface development planning with the ARP4761A safety assessment process. An item's IDAL equals the highest FDAL among the functions it implements, and safety assessment depth scales with the development assurance level. Trigger: ARP4754A systems planning, FDAL allocation, IDAL allocat...

Use when you must run requirements validation for an aircraft or system program per ARP4754A: select the validation method, confirm independence is provided where the development assurance level requires it, and score validation closure before the requirements are released to design. Produces the method verdict, the independence flag, and the closure score that gate the validation phase. Trigger: requirements validation, arp4754a, validation method, independent validation, development assuran...

Use when you must plan system level verification per ARP4754A: assign a verification method (test, analysis, demonstration, or inspection) to each requirement, check the method is acceptable for the development assurance level, require independent verification where the level demands it, and score verification coverage, including the derived requirements, against the safety assessment outputs before the evidence is released. Produces the method register, the independence flag, and the coverag...

Use when you must quantify the common-cause contribution to redundant-channel failure: split a component failure rate into the independent rate (1 - beta) * lambda and the shared common-cause rate beta * lambda, compute the common-cause shock probability Q_cc = 1 - exp(-beta * lambda * t), compute the dual-channel failure probability that combines the independent double failure with the common-cause shock by inclusion-exclusion, and compute the CCF enhancement ratio over the independence-only...

Use when you must plan or review common cause analysis for a safety assessment per ARP4761A: score the zonal safety analysis items in a zone, check that the analysis set covers zonal, particular risk, and common mode analysis, and flag zones that need action. Produces the zone score and verdict, and the common cause analysis set completeness check. Trigger: common cause analysis, zonal safety analysis, particular risk analysis, common mode analysis, arp4761a, zsa.

Use when you must run a forward event-tree analysis of the sequences from an initiating event: enumerate every binary branch path through an ordered list of mitigating functions, each with its success probability, roll up each end-state outcome frequency as the initiator frequency times the product of the branch probabilities along the path, rank the end-state paths by frequency, sum the frequency over the paths that reach the failure end state, and screen the ranked sequences against the ARP...

Use when you must quantify and rank the failure modes of an item by their rate-based criticality: split the item failure rate into per-mode rates with the mode ratios, compute the MIL-STD-1629A style criticality number C_m = beta * alpha * lambda_p * t for every mode with its failure-effect probability, sum the per-mode criticalities into the item criticality C_r, and rank the modes by C_m with each mode's share of item criticality and a dominant-mode flag. Produces the per-mode rate split, t...

Use when you must estimate or demonstrate aircraft system failure-rates from test or service data per ARP4761A: compute the point failure-rate estimate from the number of failures and the test-hours, derive the exact poisson chi-square upper-bound on the failure-rate at a stated confidence, apply the zero-failure rule (1.609 million test-hours demonstrate a 1e-6 per hour rate at 80 percent confidence), size the test-hours needed to demonstrate a target rate with allowed failures, and bound th...

Use when you must rank basic events of a fault tree by importance: compute the Birnbaum measure, the Fussell-Vesely measure, the risk achievement worth (RAW) and the risk reduction worth (RRW) of each basic event from the minimal cut sets and the basic-event probabilities, sort the events by each measure, and flag the dominant contributors above a Fussell-Vesely threshold. Produces the per-event measure dict, the sorted rank list and the dominance list that gate risk-reduction prioritization....

Use when you must quantify a fault-tree top event from its minimal cut sets and basic-event probabilities: compute the rare-event approximation (sum of cut-set probabilities), the Esary-Proschan min-cut upper bound, and the exact inclusion-exclusion top probability when 2^n stays tractable; truncate the cut sets below an analyst probability threshold and keep the retained probability share; rank the cut sets by per-cut-set probability share to flag dominant failure combinations. Produces the ...

Use when you must quantify the epistemic uncertainty band around a quantified fault-tree probability: convert each basic-event lognormal error factor to a lognormal sigma with the 90 percent normal quantile, combine the per-event sigmas into the lognormal sigma of the tree probability weighted by the Fussell-Vesely fractions, form the two-sided 90 percent lognormal-confidence-band around the top probability, compute the exceedance-probability of the true value above a target probability, and ...

Use when you must verify the coverage of the failure-mode effect rows over the functional-hazard condition set: map every FMEA row to the failure condition it demonstrates through its condition_id, list the covered and the uncovered condition ids, flag the rows that carry no condition link as orphan rows, and report the coverage ratio of covered over total conditions. Breaks the coverage down per severity class when conditions carry severity, and suggests candidate condition ids for unlinked ...

Use when scoping or executing FTA (fault tree analysis) and FMEA (failure modes and effects analysis) per ARP4761A: compute minimal cut sets from AND/OR gate structures, check cut-set probability sanity against the top event probability, select the analysis set for an assurance level (FTA/FMEA always, CCA at levels A and B), and map FMEA failure-condition severity to development assurance levels. Pairs with ARP4754A development assurance; all logic is deterministic, offline stdlib. Trigger: f...

Use when the safety assessment starts with functional hazard assessment or an FHA worksheet must be produced. Identify and rate the failure conditions of a functional hazard assessment (FHA) per ARP4761A: derive the A-FHA and S-FHA failure conditions from each aircraft or system function, rate severity into the categories catastrophic, hazardous, major, minor, and no safety effect, map each severity to its quantitative probability target (extremely improbable below 1e-9/flight-hour, extremely...

Use when you must roll LRU-level failure rates and repair-task times into a system maintainability prediction: compute the failure-rate-weighted MTTR as the lambda-weighted mean of the per-LRU mean repair times, build the lognormal repair-time model on the failure-rate-weighted median t50, derive the t50 and t95 repair-time percentiles with the Acklam inverse normal quantile, and pass or fail the predicted t95 against the maximum-repair-time requirement with the margin. Produces the weighted ...

Use when you must run a quantitative Markov analysis for an aircraft system safety model per ARP4761A: compute continuous time Markov chain state probabilities from the transition rate matrix, evaluate two-state failure and repair availability with steady state limits, derive the non-repairable failure probability and the mean time to failure, sum series failure rates, and estimate redundant configuration reliability with k-out-of-n combinations. Produces the state probability vector, the ava...

Use when you must run or review the operating and support hazard analysis (O&SHA) for an aircraft or system per ARP4761A: identify hazards from operational scenarios and maintenance tasks, score each hazard on the severity by likelihood risk matrix, assign the risk index and acceptability band, and flag safety critical maintenance tasks for the hazard log. Produces the scored hazard register, the acceptability verdict per hazard, and the critical task list that feed the system safety assessme...

Use when you must perform or review a particular risk analysis (PRA) per ARP4761A: quantify the probability of a single-event risk (rotor burst, tire burst, bird strike, fire, lightning), combine it with the conditional probability that the hazard leads to a failure condition, and assess hazard zone containment, separation, and redundant routing mitigations. Produces event-exposure probabilities, combined failure-condition probabilities, and zone verdicts for the safety assessment. Trigger: p...

Use when conducting the preliminary system safety assessment (PSSA) per ARP4761A: derive safety requirements from FHA outcomes, allocate function and item development assurance levels (FDAL/IDAL) to the proposed system architecture, and apportion the quantitative safety target for each failure condition across the contributing channels and functions. The PSSA uses fault tree, failure mode, and common cause analysis style arguments to show that the architecture can meet the quantitative safety...

Use when you must allocate a system reliability requirement down to the design items: flow one top-level failure rate per flight hour, or its MTBF equivalent, into per-item target rates by equal split or by complexity-weighted apportionment from design-team complexity weights, produce the per-item failure-rate and MTBF targets for the item development specifications, verify the series-sum closure of the item budgets against the system rate, and report each item capability margin against its p...

Use when you must analyze aircraft system reliability with a reliability block diagram (RBD) per ARP4761A: evaluate a structure of blocks in series from constant failure-rate components, compute component and system mission reliability R(t) = exp(-lambda t), combine series, active parallel, k-out-of-n voting and cold standby redundancy blocks, derive exact block and system MTBF, convert a non-exponential block to an equivalent failure rate -ln(R)/t, and identify the dominant component whose f...

Use when you must determine whether a system failure rate is improving over development or field test time: fit the Duane growth slope by ordinary least squares of the log cumulative failure rate on log cumulative time, fit the Crow-AMSAA power-law process shape beta by deterministic MLE bisection, and read the growth verdict off the fitted shape against the 1.0 boundary. Produces the duane-growth-slope, the amsaa-shape-beta with the lambda scale, the fitted current-mtbf under both estimators...

Use when planning or conducting the civil-aircraft safety assessment process per ARP4761A: classify failure-condition severity, run the FHA/PSSA/SSA sequence at the right design maturity, and scope the analysis set (FTA, FMEA, CCA) that scales with the development assurance level. Severity propagates into assurance (A = Catastrophic through E = No safety effect), the assessment plan is part of the program planning artifacts, and common-cause analysis covers zonal, particular-risk, and common-...

Use when you must close out the post-implementation safety assessment over the assessed condition set: look up the quantitative probability target per flight hour for the severity class of each assessed condition, compute the per-condition margin of target over predicted with the strict meets verdict, roll the conditions up into the closure-gate verdict with the closed and open counts, the open condition ids and the per-severity-class closure fraction, and roll the safety requirement verifica...

Use when you must perform or review the zonal safety analysis per ARP4761A: identify the physical zones of the aircraft, classify each zonal hazard by severity, assess separation and containment between the zone sources and the protected components, confirm the zonal hazard checklist is complete, and produce the ZSA report for the safety assessment. The zonal safety analysis finds the hazards created by the zone contents and the external threats that enter the zone, and flags the zones that n...

Use when you must determine the applicable certification regulations and the certification path for a civil aircraft or system: map the project type and aircraft category to the governing airworthiness parts (FAR-25 or CS-25 for transport airplanes, Part 23 or CS-23 for normal airplanes, Part 27 and Part 29 for rotorcraft, Part 33 for engines, Part 35 for propellers), identify special conditions when the design has a novel or unusual feature not covered by the regulation, and select the certi...

Use when you must develop an Equivalent Level of Safety (ELOS) finding for a civil aircraft or system certification item that cannot show literal compliance with an applicable airworthiness regulation paragraph: state the regulation intent and its safety objective, quantify or qualify the achieved safety level of the design, list the compensating measures that close the gap, compute the safety margin against the numeric probability target (25.1309 catastrophic 1e-9 per flight hour) when the r...

Use when you must select the means of compliance for each certification item in a civil aircraft certification program: assign the acceptable MOC class (moc-1 engineering analysis, moc-2 ground test, moc-3 flight test, moc-4 simulation tool, moc-5 similarity, moc-6 safety assessment) from deterministic suitability rules over item kind, severity class, DAL and a novelty screen, gate top-severity systems items on moc-6, and score the compliance matrix coverage per item kind. Produces the per-it...

Use when you must develop the Master Minimum Equipment List (MMEL) proposal for a transport type design from the safety assessment results: screen each candidate equipment item for dispatch relief with the item inoperative, classify it as MMEL-eligible or forbidden from relief, assign the operator repair interval category (A, B, C, or D), attach the (O) operating procedure and (M) maintenance flags, and check the interaction of multiple inoperative items so no combination removes a safety fun...

Use when you must evaluate airworthiness directive compliance: test each aircraft in an operator fleet against the directive effectivity by affected model and serial range, compute the remaining compliance margin in the directive's own basis (flight cycles, flight hours, or calendar months from the effective date), classify each aircraft as open, due, or overdue against the directive grace band, and roll up the per-directive fleet compliance report with applicable, open, due and overdue count...

Use when you must classify certification maintenance items: sort each candidate from certification into airworthiness limitation items (life-limited parts, damage-tolerance inspections, fuel-tank flammability checks), certification maintenance requirements, or routine scheduled maintenance using a fixed certification-driver rule table, then compute the ALS coverage of a maintenance program as matched required items over the total required and check per-item interval compliance against the typ...

Use when you must assess in-service safety data for a civil aircraft fleet against the type-design safety assessment predictions: collect field events from service difficulty reports and airline reliability reports grouped by failure condition, compute the observed event rate over the fleet exposure, compare it with the predicted rate from the safety objective, apply the single-event rule for hazardous or catastrophic events, and decide whether the experience is safety-significant. Produces t...

Use when you must run the MSG-3 maintenance steering group decision logic to develop a scheduled maintenance program for an aircraft system or component: categorize each failure mode by effect visibility (evident to the flight crew or hidden) and consequence (safety-significant or economic-only), select the applicable scheduled maintenance task categories (lubrication, servicing, operational check, visual check, inspection, functional check, restoration, discard), and assign the interval verd...

Use when you must compile and validate a type certificate data sheet: check that every required section is present (models, type design, approved engines and propellers, weights, certification basis, operating limitations, noise standards), validate the weight block consistency (max ramp at or above max takeoff, max landing at or below max takeoff, all positive), validate the category airspeed limitations (transport requires VMO or MMO; normal, utility and acrobatic categories require VNE), c...

Use when you must build or review an N2 interface diagram for an aerospace systems engineering model: derive the NxN interface matrix from the function or component list and the interface pair list, count the interfaces per element from the row and column sums, flag the missing data links against the required interface list, and identify isolated elements with no interfaces. Produces the interface matrix, the per-element interface counts, and the missing link and isolation report that gate th...

Use when you must model system requirements in a SysML requirements diagram for model-based systems engineering: define requirement stereotype attributes (id, text, kind, priority, source), connect requirements with derive, satisfy, verify, refine, and trace relationships, roll up verification status through the requirement tree, and screen requirement text for atomicity, vague terms, and verifiability gaps. Produces the requirement tree with its status rollup, the coverage gaps for unsatisfi...

Use when you must model or verify SysML state machine behavior in an aerospace systems engineering model: build state machines with states, transitions, events, guards, and actions, simulate an event sequence to produce the firing trace, compute the reachable state set from the initial state, and detect unreachable states and transition conflicts where two guards enable the same event. Produces the firing trace, the reachable set, and the conflict list that gate the behavioral model review. T...

Use when you must create or check SysML models for model-based systems engineering in an aerospace program: select the right SysML diagram kind for each modeling purpose (block definition BDD, internal block IBD, parametric, requirement, activity, sequence, state machine, use case), draft block definition and internal block diagrams from the system structure, build requirements diagrams with traceability closure, set up parametric diagrams for constraint-based analysis, and judge model viewpo...

Use when running model-based systems engineering for an aerospace program: sequence the modeling workflow (requirements modeling, functional and logical architecture, allocation, analysis, traceability), check that every function is allocated to a design element, verify traceability closure (full for safety-critical items), and map modeling tasks to open-source toolchains such as Capella, OSATE, and Papyrus. Models are the primary artifacts; the systems engineering process follows the mapped ...

Use when you must run a trade study or alternative selection for an aerospace system or subsystem: set decision criteria with weights that sum to 1.0, score each candidate, build a Pugh matrix with plus/zero/minus marks against a baseline concept, compute weighted scores, judge the selection margin between the best and runner-up alternative, perturb the weights to test sensitivity, and confirm every candidate traces to requirement ids. Produces the ranked alternative list, the Pugh verdict, t...