Type Certificate Data Sheet

Type Certificate Data Sheet (systems-engineering-safety/continued-airworthiness/type-certificate-data-sheet)

Use when a type certificate data sheet style type design record must be compiled, validated or revised: checking the required section set, the weight block, the category airspeed limitations and the approved engine and propeller configuration, then summarizing counts or diffing two revisions for a type certificate amendment or an STC integration review. This leaf implements the TCDS record checks in pure Python, stdlib only: every check is a small deterministic function over a plain dict record. It pairs with the certification-basis leaf in this family, which decides the regulation set and approval route that the certification_basis section of the record then quotes, and with the airworthiness-limitation leaf in this pack, which reads type-certificate limitation data as an input to maintenance-program checks.

Domain quick reference

• Record shape: a dict with a "category" key plus the required sections REQUIRED_SECTIONS = (models, type_design, engine_models, propeller_models, weights, certification_basis, operating_limitations, noise_standards). The models, engine_models and propeller_models sections are lists, weights is a dict holding max_ramp, max_takeoff and max_landing, and operating_limitations is a dict of named limits.
• Section presence: missing_sections returns the REQUIRED_SECTIONS keys absent from the record. Content checks inside sections that exist are separate: a missing section is reported once by missing_sections.
• Weight block rules: every weight is positive; max_ramp at or above max_takeoff (ramp below takeoff is an error, the fuel for start and taxi is not yet burned); max_landing at or below max_takeoff (landing weight is limited to the takeoff certified value).
• Category airspeed rules (CATEGORY_AIRSPEED_KEYS): transport requires VMO or MMO, any one key present and positive satisfies the rule; normal, utility and acrobatic categories require VNE. These follow the Part 25 transport limit philosophy (VMO/MMO envelope) versus the legacy Part 23 category rule set (VNE placard), handled here as data.
• Approved configuration: a TCDS lists the approved engine and propeller models, so engine_models and propeller_models must be non-empty; operating_limitations may carry an optional "engines" list of engine model references and each reference must appear in engine_models.
• Revision diff: tcds_revision_diff maps each section key to unchanged, added, removed or modified, reports the per-model change of the models section as models_added and models_removed, and the weight changes as "_delta" floats such as max_takeoff_delta.
• Units: weights in the worked examples are kg and airspeeds are labeled in the record (ktas for VMO, Mach for MMO); limits keep the units the record declares, values are compared as numbers.
• Regulatory frame: FAR 25 is named only as the transport certification standard the sheet records, with the legacy Part 23 category rules and the FAR 36 noise standards treated as data entries.

Workflow

1. Assemble the draft type design record as a dict with a "category" key and the section keys of the sheet being compiled.
2. Check section presence with missing_sections(record) and fill any REQUIRED_SECTIONS key that is absent.
3. Validate the weight block with weight_errors(record) and correct any missing, non-positive or inconsistent weight entries.
4. Validate the category airspeed limitations with airspeed_errors(record): transport needs VMO or MMO, the smaller categories need VNE.
5. Check the approved configuration with approved_config_errors(record): non-empty engine and propeller model lists and, when present, engine references in operating_limitations that all appear in engine_models.
6. Run the aggregate check validate_tcds(record) and read the missing_sections, weight_errors, airspeed_errors, config_errors lists and the valid flag; valid is True exactly when all four lists are empty.
7. Summarize the record with tcds_summary(record) for the model counts, the max takeoff weight and the sorted airspeed limit list.
8. For a type certificate amendment or STC integration review, diff the old and new revisions with tcds_revision_diff(old, new) and read the per-section statuses, the added and removed models, and the weight deltas.
9. Confirm the deterministic checks with the contract test scripts/test_type-certificate-data-sheet.py.

Worked example

Record A: category "transport", models ["T-100"], type_design "T-100 basic", engine_models ["E-1", "E-2"], propeller_models ["P-1"], weights {max_ramp 80000, max_takeoff 79000, max_landing 70000} (kg), certification_basis ["far-25"], operating_limitations {vmo 340 (ktas), mmo 0.84}, noise_standards ["far-36"].

• missing_sections(A) == [], weight_errors(A) == [], airspeed_errors(A) == [] (transport satisfied by vmo 340), approved_config_errors(A) == [].
• validate_tcds(A) valid True with all four error lists empty.
• tcds_summary(A): models 1, engine_models 2, propeller_models 1, max_takeoff_weight 79000.0, airspeed_limits ["mmo=0.84", "vmo=340"].
• Record B: category "normal" with weights {max_ramp 75000, max_takeoff 79000, max_landing 70000} and operating_limitations {}: weight_errors(B) = ["max_ramp below max_takeoff"] and airspeed_errors(B) = ["missing vne for category normal"], so validate_tcds(B) valid False.
• Revision A2 adds model "T-101" and changes max_takeoff to 79400: tcds_revision_diff(A, A2) reports sections models "modified" and weights "modified", models_added ["T-101"], models_removed [], and weight_deltas {"max_takeoff_delta": 400.0}.
• Configuration spot check: operating_limitations with an "engines" list ["E-9"] gives the error "engine reference E-9 not in approved engine models".

Verification

• Confirm missing_sections on a record without propeller_models and noise_standards returns exactly those two, in section order.
• Confirm the weight rules: ramp below takeoff flagged, landing above takeoff flagged, non-positive and zero weights flagged, and a record with no weights section returns no weight errors (section absence is reported by missing_sections).
• Confirm the airspeed truth table across all four categories and that an unknown category is flagged.
• Confirm validate_tcds(A) valid True and validate_tcds(B) valid False with the two content errors of the worked example.
• Confirm the identities: valid equals all four error lists empty, summary counts equal their list lengths, a diff of a record with itself is all "unchanged", and models_added and models_removed are disjoint.
• Confirm ValueError rejection of non-physical inputs: a record without a "category" key, a weights section that is not a dict, an operating_limitations section that is not a dict, and non-numeric weight or airspeed values.
• Confirm the module is deterministic: the same record gives the same validation dict on every run.
• Run the contract test offline: python3 scripts/test_type-certificate-data-sheet.py (35 tests, deterministic).

Related leaves

• systems-engineering-safety/certification/certification-basis: decides the regulation set and approval route that the certification_basis section of the record then quotes.
• systems-engineering-safety/continued-airworthiness/ ica-cmr-ali-classification: downstream in this pack, consumes the type-certificate limitation data when a maintenance program is checked against the airworthiness limitations of the type.
• systems-engineering-safety/continued-airworthiness/ in-service-safety-assessment: the field review that reacts to events on the certified type after it enters service.
• systems-engineering-safety/arp4754a/configuration-management: change control over the type design record when the sheet is amended.

Pitfalls

• Confusing section presence with section content: missing_sections reports only absent REQUIRED_SECTIONS keys, so a record with a weights section whose keys are wrong gets no missing-section entry but does get "missing weight key ..." entries from weight_errors; read both lists from validate_tcds.
• Treating a present but empty section as complete: operating_limitations {} is present, so it never appears in missing_sections, yet the category airspeed rule still fails for it (Record B shows exactly this: no missing sections, but "missing vne for category normal").
• Requiring every airspeed key: the category rule needs any one listed key present and positive, so a transport record with VMO alone is valid without MMO, and MMO alone satisfies it too.
• Checking engine references against an empty approved list: when engine_models is empty the config check reports "no approved engine models listed" and skips the reference comparison, so an "engines" entry does not cascade into duplicate reference errors.
• Ignoring the units declared in the record: the worked example mixes ktas (VMO 340) and Mach (MMO 0.84) inside one operating_limitations dict, and weights in kg; values are compared as numbers with the units treated as labels, so compare like for like.
• Reading a revision diff as a full history: tcds_revision_diff gives the state change between exactly two revisions, not the amendment trail, and a reordering of models inside the list counts as "modified" with empty added and removed lists.

Behavior contract (gate 3)

Run the deterministic contract test (stdlib unittest, offline):

python3 scripts/test_type-certificate-data-sheet.py

The test covers the worked example (record A valid, record B invalid with "max_ramp below max_takeoff" and "missing vne for category normal"), the missing-section lists on partial records, the weight rule truth table (ramp below takeoff, landing above takeoff, non-positive and missing weight keys), the category airspeed truth table across all four categories with the unknown-category flag, the approved configuration checks including engine references, the summary counts and sorted airspeed limits, the revision diff (added and removed models, weight deltas, self-diff all unchanged, disjoint added and removed), the identity valid == all error lists empty, determinism, and ValueError rejection of records without a category, non-dict weights or operating_limitations sections, and non-numeric values.

Compliance

• Standards referenced, not reproduced: FAR 25 frames the transport certification basis that the sheet records and FAR 36 the noise standards entry, while the legacy Part 23 category airspeed rule is carried as data; all are named as context only and the rules above are summary-only per standards-map.yaml.
• compliance: STANDARDS-REF, gated: false.