BazB is right.
I wasn't so much a case of contamination causing the electrical box (indeed 5GC) to fail causing the Wheel N/W STRG Fault ECAM caution.
It was more that on occasion (and without failure message), when the lever was moved and pinned to TOW the microswitch did not function electrically.
As the engines were then started on pushback and hydraulic pressure became available, the NWS would center and break the shear pins in the tow bar.
TFU 32.51.12.005 refers to both issues with the 5GC Electrical Box, both the N/W STRG Fault Ecam and the pressurisations during towing operations.
Last edited by T.R Haychemu; 21st Jan 2013 at 17:20.