ASTM F3338 — Standard Specification for Design of Electric Engines (Electric Propulsion Units) for General Aviation Aircraft establishes minimum design requirements for Electric Propulsion Units (EPUs) including configurations with distributed electric propulsion. It is developed under ASTM F39 and accepted by the FAA as a Means of Compliance for Part 23 (normal category) aircraft type certification.
Scope
F3338 covers the EPU — the electric motor and its associated power electronics, controller, and cooling system — as a discrete airworthiness article. It applies to both single-motor and distributed-propulsion configurations and sets design, performance, and qualification requirements intended to give certifying authorities confidence in EPU airworthiness without requiring novel special conditions on a case-by-case basis.
Battery system relevance
While F3338 is primarily a motor/drive standard, its requirements create important constraints for the battery system:
- EPU voltage and current interface specifications determine the battery pack voltage window and continuous/peak current ratings
- EPU fault behaviour (e.g., shoot-through, regenerative braking limits) defines protection requirements for the battery BMS
- Thermal interface requirements between EPU and thermal management system may be shared with the battery cooling loop
- Distributed propulsion configurations may require multiple independent battery strings for fault tolerance
References
- ASTM F3338-24 Standard Specification for Design of Electric Engines for General Aviation Aircraft, ASTM International
See also: ASTM F3316/F3316M, ASTM F3239, ASTM F3653