--- title: "Qualification" canonical: "https://anchor.is/the-hysteresis/issue/7/qualification" publication: "The Hysteresis" publisher: "The Hysteresis" language: "en-US" guide: "https://anchor.is/the-hysteresis/llms.txt" permalink: "https://anchor.is/the-hysteresis/issue/7/qualification" issue: 7 section: "qualification" description: "Pack-level requirements, test conditions, and standards by application" authors: ["Ronan Adike"] published: 2026-07-27 updated: 2026-07-25 articles: 19 --- # The Hysteresis > The Hysteresis exists to give a small cross-functional team — strategy, investment, and procurement — a shared weekly instrument for reading the battery supply chain earlier than consensus. Success means the team consistently identifies inflection points in cell pricing, supplier health, and policy enforcement weeks or months before they surface in earnings calls, annual surveys, or trade press. The commercial mechanism is internal-first: the publication proves itself as a decision tool inside the organization, then extends to paid subscribers and a practitioner community as upside. Revenue follows utility — if the team makes better-timed procurement calls and competitive assessments because of what they read here, the publication earned its place. [Read on the website]() ## Issue 7 — Qualification Pack-level requirements, test conditions, and standards by application ### eVTOL Standards Map - [eVTOL / Powered-Lift Pack Qualification Standards Map]() — By [Ronan Adike]() · Published 2026-07-24 · Format: The Standards Map Eleven parameter classes matter for eVTOL propulsion-pack qualification. One is settled. Four have test frameworks but no assigned severity levels. Four more, energy density, C-rate capability, cycle life, calendar life, carry no public threshold at all. Every DVP row in those classes gets closed by the applicant's own engineering analysis, accepted on a program-specific basis by the certifying authority. Not by a standard. This card maps the full layered structure across FAA AC 21.17-4, EASA MOC VTOL.2440, DO-311A, and DO-160G: what each document actually covers, where each one's scope terminates, and where the DVP is working without a net. ### DVP Parameter Cards eVTOL propulsion-pack qualification does not resolve to a single document. The regulatory structure spans jurisdictions and remains partially unfinished. EASA's MOC stack builds propulsion-specific thermal runaway, crash resistance, and inertial load requirements on top of a DO-311A baseline that was never written for these batteries. The FAA's AC 21.17-4 defines aircraft-level energy system objectives and publishes no pack-level test parameters. ASTM F3830-26, active since June 2026, covers light-sport ESS only. Cards below cite the governing document, clause, and threshold where standards are settled. Where no standard exists, the gap is named. C-rate and cycle life, two parameters that appear on every eVTOL DVP, have no governing standard as of July 2026. The void is the content. - **MOC-3 Layers Propulsion Tests Over DO-311A Baseline** — [Source]() — Published 2026-07-24 Tag: Thermal Runaway EASA MOC-3 SC-VTOL Issue 2 (enhanced category). DO-311A §2.4.5.5 containment test was not developed for propulsion batteries; EASA acknowledges this explicitly. Two evidence paths: non-propagation (stabilization at 55°C, ≥8 hr monitoring) or continued-safe-flight containment (≥20% of cells driven into thermal runaway). Test definition requires EASA coordination on a per-program basis. Last verified 2026-07-17. - **Installed ESS Drop: 15.2 m, Non-Deforming Surface** — [Source]() — Published 2026-07-24 Tag: Crash Resistance EASA MOC VTOL.2325(a)(4). Drop height ≥15.2 m onto non-deforming surface, ESS in most critical expected crash condition. Post-drop acceptance: fire or harmful leakage contained ≥15 minutes outside evacuation path. Scope: installed-ESS criterion, not standalone pack drop. Last verified 2026-07-17. - **Five Ultimate Load Factors for Cabin-Installed ESS** — [Source]() — Published 2026-07-24 Tag: Inertial Loads EASA MOC VTOL.2325(a)(4), cabin ESS. Ultimate inertial load factors: 4g upward, 16g forward (18g for CTOL configurations), 8g sideward, 20g downward, 1.5g rearward. These are aircraft-installed criteria under SC-VTOL, not generic pack enclosure structural requirements. Last verified 2026-07-24. - **AC 21.17-4 Sets Aircraft-Level Energy System Objectives** — [Source]() — Published 2026-07-24 Tag: FAA Certification FAA AC 21.17-4 (issued 2025-07-18), PL.2430. Five criteria: energy provision, usable energy display to flightcrew, safe energy removal/isolation, energy retention under likely operating conditions, post-crash hazard minimization. All performance-based, all aircraft-level. No pack-level C-rate, cycle-life, or abuse test matrix published. Last verified 2026-07-24. - **DO-311A Alone Cannot Close Propulsion-Pack Acceptance** — [Source]() — Published 2026-07-24 Tag: EASA Posture MOC-4 SC-VTOL Issue 2 (final, 2025-07-11): accepts DO-311A or ETSO C-179b only when aircraft-level risk assessment and hazard controls are layered on top. MOC-5 Issue 1 remains post-consultation, not final (consultation closed 2025-10-10). Propulsion-pack acceptance requires the full MOC stack, not a single document. Last verified 2026-07-17. - **ASTM F3830-26 Governs Light-Sport ESS Only** — [Source]() — Published 2026-07-24 Tag: Scope Boundary ASTM F3830-26 (active June 2026). FAA accepts it as consensus standard for electrical ESS under Part 22, light-sport category aircraft. It does not govern powered-lift or eVTOL programs certifying under AC 21.17-4 or EASA SC-VTOL. Applying F3830-26 to those programs is a category error. Last verified 2026-07-16. - **No Standard Governs eVTOL C-Rate Requirements** — [Source]() — Published 2026-07-24 Tag: C-Rate Gap Gap. No governing standard exists. Yang et al. (Joule, 2021) provides the most-cited analysis: hover/takeoff 2.5–4.5C, cruise 0.75–1.5C, peak-power bursts 30–120 s. Assumes 200 Wh/kg (gravimetric) pack, battery weight fraction 0.3. C-rates climb at lower specific energy. DVP must derive values from actual vehicle duty cycle. Last verified 2026-07-24. - **Cycle Life Remains Program-Defined, No Standard** — [Source]() — Published 2026-07-24 Tag: Cycle-Life Gap Gap. No governing standard. Yang et al. (Joule, 2021) estimates ~1,600 equivalent full cycles per year at high utilization. The 20% capacity-fade EOL criterion borrowed from EV programs does not transfer: power fade and reserve energy retention govern landing hover and balked-landing margins. DVP must specify EOL criterion, DOD, charge rate, and test temperature independently. Last verified 2026-07-24. ### Research Layer - **Lithium-Ion Battery Power Performance Assessment for the Climb Step of an eVTOL Application** — [Source]() — Published 2026-07-24 ORNL tested commercial cells under a 15C discharge pulse representative of eVTOL takeoff climb. Lithium plating was the dominant degradation mode at propulsion-grade C-rates. Published Feb 2024 in ACS Energy Letters (open access, PMCID: PMC10928709). Tier 3 source. Which DVP gap? No standard governs eVTOL climb-phase C-rate testing. ORNL's 15C pulse protocol is a citable empirical basis for program-defined DVP rows. Why does degradation mode matter? Lithium plating under high-rate pulses drives capacity fade pathways distinct from steady-state cycling, affecting cycle-life acceptance criteria. - **Safety Assessment for Battery Thermal Runaway Propagation for Urban Air Mobility** — [Source]() — Published 2026-07-24 TU Munich applies EASA MOC3 SC-VTOL as the governing TRP compliance framework for manned eVTOL, using fault tree analysis per SAE ARP4761. Cell-to-cell non-propagation alone fails manned safety targets. Thermal barrier mass penalties reach 17.3% of pack mass. Which compliance framework? The paper uses EASA MOC3 SC-VTOL over DO-311A, confirming the multi-document regulatory structure for manned eVTOL TRP qualification. What does this mean for pack design? TRP containment is a mandatory pack-level architecture layer; cell-level non-propagation does not close the safety case alone. - **Safety Design of Aviation Propulsion Lithium-Ion Battery Systems Based on Thermal Runaway Explosion Index** — [Source]() — Published 2026-07-24 Civil Aviation University of China proposes a composite Thermal Runaway Explosion Index (TREI) integrating inherent hazard, operational conditions, and protective design. Covers four DVP-relevant environmental stressors: low temperature (to −15°C), low pressure (70 kPa at 3,000 m), high-rate discharge, and vibration. What's the methodology? A single quantitative index linking temperature, altitude pressure, C-rate, and vibration conditions for aviation propulsion pack safety scoring. Where does it apply in a DVP? Supplies rationale for combined-condition test sequencing when multi-stressor scenarios need documented justification. Tier 3 methodology, not a standard. - **Novel Battery Power Capability Assessment for Improved eVTOL Aircraft Landing** — [Source]() — Published 2026-07-24 University of Warwick defines a method for setting the minimum usable SOC threshold below which voltage sag compromises power delivery during eVTOL landing. No governing standard addresses this parameter. The paper provides a documented methodology for a program-defined reserve-energy DVP call. Which DVP gap? Minimum landing-phase SOC floor has no standard home. This methodology gives the documented rationale for that program-defined threshold. How does it fit the broader picture? Addresses the landing power spike, complementing ORNL's climb-phase work to bracket both mission-profile extremes where battery limits bind. ### DO-311A Scope Boundary - [DO-311A is not your eVTOL propulsion pack qualification]() — By [Ronan Adike]() · Published 2026-07-24 EASA says it plainly. DO-311A §2.4.5.5's thermal runaway containment test "was developed for lithium batteries that provide power to other aircraft systems or equipment" — not propulsion batteries ([MOC VTOL.2440 §1](https://www.easa.europa.eu/en/document-library/easy-access-rules/online-publications/easy-access-rules-small-category-vca?page=17)). Citing it alone in a propulsion pack DVP misrepresents the regulatory posture. ### Source Access - **FAA AC 21.17-4: Type Certification Procedures for Powered-Lift Aircraft (July 2025)** — [Source]() — Published 2026-07-24 Sets aircraft-level energy system functional objectives that pack-level DVP test evidence must trace to for U.S. type certification. - **EASA SC-VTOL and Means of Compliance (MOC-4 Issue 2, MOC-5 consultation)** — [Source]() — Published 2026-07-24 Gateway to the MOC document family governing EASA's battery certification layers, including MOC-4 Issue 2 and MOC-5 draft status. - **EASA Easy Access Rules for Small-Category VCA: MOC VTOL.2440 and MOC VTOL.2325(a)(4)** — [Source]() — Published 2026-07-24 Covers the strongest public pack-level parameters: thermal runaway propagation limits, 15.2 m drop test, and installed ESS inertial load factors. - **ASTM F3830-26: Propulsion Battery ESS Qualification for Light Sport Aircraft (June 2026)** — [Source]() — Published 2026-07-24 Newest aviation propulsion-battery standard published, though scoped to light-sport category and not directly applicable to powered-lift eVTOL pathways. - **RTCA DO-311A: MOPS for Aircraft-Installed Rechargeable Lithium Batteries (Dec 2017)** — [Source]() — Published 2026-07-24 Referenced by FAA TSO-C179b and EASA MOC-4 for baseline safety tests, but scope explicitly excludes large propulsion battery systems. ## Other sections in Issue 7 - [Signal]() - [China]() - [Korea]() - [The Log]() - [Defense]() ## More - [Publication guide]() - [Issue archive]()