System

{{entity:Kids Remote Control Airplane}} ({{hex:DEEC1058}}) with 176 requirements across 6 documents, 3074 trace links, and 90 VER entries. This session executed Flow D — full V-model verification and validation review. The project reached qc-reviewed status after session 493; this session targeted the validation verdict.

Verification Audit

Ten VER requirements sampled covering all subsystems. Seventy-two of 90 use {{trait:Processes Signals/Logic}} Test method; 10 Inspection, 8 Demonstration — a reasonable distribution. Three specific issues were found and corrected:

VER-REQ-084 criterion mismatch (fixed): {{sys:SYS-REQ-005}} specifies thermal cutoff at 45°C. The acceptance criterion in VER-REQ-084 read “cutoff at <60°C” — 15°C above the specification threshold, meaning a non-compliant charger that cut out at 59°C would have passed the test. The criterion was corrected to ≤45°C with a thermal pad simulation method that achieves a controlled and repeatable battery surface temperature.

VER-REQ-071 method reclassified (fixed): {{ifc:IFC-REQ-021}} is tagged SIL-2 and the VER entry included applying 30 A from a bench supply to confirm PTC fuse rating. Logging the method as Inspection while requiring a live current application is inconsistent with IEC 61508 — the method was reclassified to Test.

Missing trace links (fixed): {{sub:SUB-REQ-001}}, {{sub:SUB-REQ-003}}, and {{sub:SUB-REQ-004}} had no formal “verifies” trace links to their corresponding VER entries (REQ-SEKIDSREMOTECONTROLAIRPLANE-001 through 003) despite explicit textual references in each VER entry. Three trace links added.

Overall VER trace coverage post-fix: SUB 29/29, IFC 22/22, SYS 12/12. STK requirements are covered indirectly through the SYS derivation chain, which is correct V-model practice.

Scenario Validation

flowchart TB
  n0["system Kids Remote Control Airplane"]
  n1["subsystem Airframe Subsystem"]
  n2["subsystem Propulsion Subsystem"]
  n3["subsystem Flight Control Electronics"]
  n4["subsystem Radio Transmitter"]
  n5["subsystem Power System"]
  n6["subsystem Ground Charging System"]
  n10["actor Child Pilot"]
  n0 -->|contains| n1
  n0 -->|contains| n2
  n0 -->|contains| n3
  n0 -->|contains| n4
  n0 -->|contains| n5
  n0 -->|contains| n6
  n5 -->|7.4V power| n2
  n5 -->|5V BEC| n3
  n3 -->|PWM throttle| n2
  n4 -->|2.4GHz control frames| n3
  n3 -->|servo deflection| n1
  n10 -->|stick inputs| n4

Weekend Park Flight: {{stk:STK-REQ-001}} → {{sys:SYS-REQ-009}} → VER-REQ-036 chain complete. User trial with 5 children aged 8–14 is the acceptance method. The 25-minute total session budget is broken down by setup (10 min, SYS-REQ-009) and flight/landing time; coverage is adequate.

Wind Gust Crash: Battery retention, propeller frangibility, and crash structural integrity chains are complete ({{sys:SYS-REQ-008}} → {{sub:SUB-REQ-022}}/028 → VER-080). Gap found and closed: The scenario explicitly identifies battery internal damage not visible externally leading to deferred thermal runaway. No SYS requirement addressed the post-crash user protocol. SYS-REQ-013 added: product documentation SHALL require battery disconnection, swelling inspection, grounding of deformed batteries, and the kit SHALL include a LiPo safety pouch. VER-REQ-095 verifies via documentation inspection and observed parent behaviour in 3-participant post-crash simulation.

Signal Loss Failsafe: {{stk:STK-REQ-006}} → {{sys:SYS-REQ-004}} → {{sub:SUB-REQ-018}}/027 → VER-076/086 chain complete. 500 ms timeout is bench-verified (Test) and a flight demonstration confirms descent within 30 m horizontal. Descent rate ≤3 m/s measured by barometric altimeter during glide.

Charging Fire Emergency: {{stk:STK-REQ-004}} → {{sys:SYS-REQ-005}} → {{sub:SUB-REQ-015}}/016/017 → VER-077/084 chain complete after the VER-084 thermal criterion correction. Cell overvoltage termination and thermal cutoff are both exercised in VER-077.

Routine Maintenance: {{stk:STK-REQ-008}} → VER-088 (30-minute repair trial) covers the primary maintenance scenario. Battery runtime VER-048 and LVC chain cover the capacity degradation trigger for battery replacement.

Mode Coverage

Six operating modes examined. Pre-flight Check, Normal Flight, Signal Loss Failsafe, and Battery Critical are well-covered. Battery Charging mode has complete VER coverage for the charger IC behaviour. Post-crash Inspection mode was the only mode without a user-facing procedure requirement — addressed by SYS-REQ-013.

Safety Argument

H-001 (propeller strike): complete — SIL-2, Test verification at rated RPM with quantified yield criterion. H-003 (flyaway): complete — SIL-1, failsafe chain verified by Test and Demonstration. H-004 (uncontrolled descent): complete — mass budget and stability augmentation limits constrain impact energy; failsafe descent rate covers the primary scenario. H-005 (exposed wiring): complete — battery retention and connector polarisation chains verified. H-006 (RF interference): complete — FHSS bind protocol physically prevents cross-binding.

H-002 (thermal runaway): gap closed. The safe state requires battery disconnected and isolated in fireproof container. Pre-session analysis showed no requirement making this safe state reachable by a non-technical user after a crash. SYS-REQ-013 fills this gap.

H-007 (small parts / choking): partially covered. STK-REQ-009 mandates EN 71 Part 1 small-parts compliance testing (VER-089). Age rating labelling is verified. A specific requirement for battery bay screw closure to prevent younger sibling access was not added — this is a gap for a future QC session given it is outside the current decomposition scope.

Gaps Closed

• VER-REQ-084: thermal acceptance criterion corrected (45°C)
• VER-REQ-071: verification method corrected to Test
• 3 missing SUB→VER trace links added (SUB-001/003/004)
• SYS-REQ-013 added for post-crash battery inspection protocol (H-002)
• VER-REQ-095 added to verify SYS-REQ-013
• Trace chain: STK-004 → SYS-013, SYS-008 → SYS-013, SYS-013 → VER-095 established

Verdict

Pass. All five ConOps scenarios are covered by the requirement chain from STK through VER. The one pre-session gap (H-002 post-crash safe state reachability) was closed within this session. SIL-rated requirements all carry Test verification. Baseline VALIDATED-2026-03-24 created. H-007 battery bay closure is a residual partial gap — acceptable at current maturity, flagged for next QC pass.