A320
Maintenance Airframe; Maintenance Avionics; Maintenance Powerplant
Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Procedure
Fan blower avionics vent 20HQ wiring and associated connector burnt. Connectors 358QF14 and 183QF14 were found burnt along with wiring between said connectors and blower fan control relay 8HQ. Spattered metal and soot found throughout contactor box 107VU126. This is my second aircraft to find this type of damage in the past 2-3 months. I believe this is occurring due to poor manufacture design of vent fan control system. Redesign of system.
Reporter stated this involves A320 aircraft; and it's becoming a widespread issue.  He stated they have now seen 5 aircraft with the same burned wiring; and it appears to him to be under-gauged wire spec from Airbus.
Technician reported burnt wires and evidence of arcing and fire in circuits associated with the Avionics Vent Fan Blower. Reporter further stated he has now seen a total of five aircraft with similar damage.