Fault replication increases the screening input level until known faults in the unit being screened are precipitated. These known faults may be recognized manufacturing problems or faults that have been deliberately seeded. As in the case of Method B. use of this method must be approved by the government.
Method C can be used independently to establish a screening level or can be used in conjunction with Method B. In either case, the steps involved are similar to those listed for Method B except that the testing stops at the input level necessary to precipitate the known faults.
A minimum of ten faults should be available for replication to establish an effective screening level. Ideally, the faults should be "hidden" or latent, meaning that they would not be detected during functional tests. Representative faults to be used for seeding are:
- Loose hardware
- Flawed components (transistors, relays, etc.)
- Cold solder joints
- Nicked component mounting legs
- Incorrect bonding
- Removed bonding
- Intermittent switch
- nsufficient solder
- Connector or plug partially unseated
- Nicked wires
- Fractured hardware