A Lead Mechanic with Inspection Authority reports a Eurocopter AS350 hydraulic pressure annunciator pressure switch was replaced without any documentation and no post installation operational check.

Narrative

I was informed that one of our Part 135 Rotorcraft was scheduled for an early departure the next day. The carry-on Aircraft Status Container was still placed in a 'Grounded slot' in our Pilot Briefing room. I questioned why and was told it had been placed there by mistake. I found a previous Flight Log that had a 'canceled flight' with a note another aircraft was used. I called the pilot to find out what happened. He stated that on start-up a 'Hydraulic Pressure' annunciator would not extinguish; so he took another aircraft. He informed the Director of Maintenance. The Shop Supervisor was then directed to check the aircraft and found a faulty Pressure Switch. A part was borrowed from a nearby Rotorcraft Parts Department and installed. There was no discrepancy write-up by the pilot. There was no Maintenance entry for replacing the pressure switch and a post installation Operational Check. A part was ordered by our parts person; only to be given back to the city as a replacement. There is no traceability for the switch that was installed and now our inventory records will show a part requisitioned out to the aircraft that was never installed. Our Part 135 procedures for recording discrepancies were not followed. Our Part 145 Repair Station Procedures for recording Maintenance and issuing parts were not followed. The aircraft that was used to complete the flight had an expired MEL item overdue by six days at the time of occurrence. An 'item inop' sticker was affixed to the instrument panel with the Expiration Date and a duplicate sticker was affixed to the cover of the Aircraft Status Container. Hard to ignore.