L-SYS has worked with many of the leading electric Vertical Takeoff and Landing (eVTOL) manufacturers and manufacturers that have developed Electric Propulsion Units (EPUs) for electric and hybrid-electirc powertrains e.g. MagniX, Ampaire, ZeroAvia and Zunum. The following system architectures are generic and not representative of these EPUs:
Example 1
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Example 2
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Example 3
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Example 4
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Example 5
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Example 6
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Loss of Vertical Thrust from Winding 1
Loss of thrust from EPU winding 1:
Fault Tree Analysis: Loss of Vertical Thrust from Winding 2
Loss of thrust from EPU winding 2:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Example 7
System Architecture
Fault Tree Analysis: Loss of Vertical Thrust
Total loss of thrust from both EPU windings:
Fault Tree Analysis: Loss of Vertical Thrust from Winding 1
Loss of thrust from EPU winding 1:
Fault Tree Analysis: Loss of Vertical Thrust from Winding 2
Loss of thrust from EPU winding 2:
Fault Tree Analysis: Uncommanded Thrust
Uncommanded thrust from 1 of 2 EPU windings:
Results Propulsion Unit Level Analysis
| Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 | |
| Loss of thrust | 0.0001 | 0.0001 | 0.000102 | 7.501E-9 | 2.007E-6 | 2.31E-8 | 9.118E-8 |
| Uncommanded thrust | 1e-6 | 2E-6 | 2.874E-9 | 2E-6 | 2.874E-9 | 5.749E-9 | 5.749E-9 |
AIR7130 and EASA Single Fault Tolerance and LOPC in Electric Engines
The concept of Single Fault Ratings (SFR) can be combined with the Fault Tree Analysis (FTA) completed for system architecture examples 1 – 7. Example 6 and 7 have been designed for a 50% Emergency Continuous Duration Power (ECDP) and a 50%+ Emergency Short Duration Power (ESDP) 50%+ degraded mode of operation SFR. This approach to demonstrating compliance to CS/FAR 23.2410 is described in detail by AIR7130 and EASA Single Fault Tolerance and LOPC in Electric Engines.
Generally, the approach states that an engine operating at a SFR such as ESDP/ ECDP will allow for the aircraft to perform a Continued Safe Flight and Landing and demonstrate compliance with CS/FAR 23.2410.
Also, the system architectures represented by example 6 and 7 satisfy “the essentially single fault tolerance of the engine control system to electrical and electronic failures leading to LOPC/ LOTC” that is historically applied to turbine engines.