Argument A1.2.2.3.3.4.4.3.1.1.1 The guard is simple

• Supports Claim: C1.2.2.3.3.4.4.3.1.1 The guard is adequate to prevent collision

Child nodes:

• Has evidence Evidence: E1.2.2.3.3.4.4.3.1.1.1.2 Guard schematics and assembly drawings
• Has evidence Evidence: E1.2.2.3.3.4.4.3.1.1.1.4 Propeller governor schematics and assembly drawings
• Has evidence Evidence: E1.2.2.3.3.4.4.3.1.1.1.5 Functional test report
• Has evidence Evidence: E1.2.2.3.3.4.4.3.1.1.1.1 Non functional test reports
• Has evidence Evidence: E1.2.2.3.3.4.4.3.1.1.1.3 Design Justification Report (DJR)

It uses a small number of well understood hardware components and no software.

It relies on

1. disconnecting power to the propeller motors controlled by a micro switch (initiator) and a relay.
2. the propeller rotation speed being governed. This is required because excess speed will prevent the guard reacting in time. This is achieved by a simple pulse counter from a hall sensor and magnet (on the propeller shaft) which removes power to the propeller motors if the count rate is exceeded.

100% test coverage has been achieved.

The design is justified in the Design Justification Report (DJR)