GUys,
Just to add some detail that might be useful. The CVS flight deck tractors were fitted with special demin water tanks that replaced existing ballast weights. The installation also included a pump, hose and nozzle for the water washes described in earlier posts. Water wash was, as many have said here, a standard routine post last flight of the day. However, this really only washed the LP compressor section, as it threw almost all the water out the front nozzles.
The Sea Harrier Pegasus engine (might have applied to all Peggies) was also fitted with an integral water wash system that worked via a connection located under a belly panel. This was used during 'remedial' compressor washes in cases of power loss. A very effective system.
Hope this helps
Best regards as ever to those doing the work on the decks,
Engines