B757-200
Maintenance Powerplant; Maintenance Airframe
Maintenance Technician 23
Situational Awareness; Troubleshooting; Communication Breakdown; Distraction
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Logbook Entry; Procedure; MEL; Human Factors
A B757-200 aircraft arrived in ZZZ. A call from the crew about an arming problem at Door-4R (Right).  At that time I was driving up to the gate and saw a Mechanic on his golf cart. I asked him who was working this item and he told me there was a Mechanic onboard.  Door-4R had opened and Mechanic was dusting the door sill and swept off some debris looking like a shell from the sill. Door was closed and time went on for about a minute or so. I called the Mechanic on the radio to see if it was OK; no response from the Mechanic at this time. About two minutes later; the Mechanic got on his cart and drove to me at the back of the aircraft and told me everything was good; but he did have a problem with the door slide light and that the [flight] crew was alright with taking the aircraft. At that time I dropped that plane to go for another aircraft.The Lead had called on the radio to see if he could sign this item off and what fixed the item. My response on the radio was a shell was dusted off the sill and it fixed the problem. The Mechanic was already headed to the [Maintenance] Room at this time and I assumed he would create a Deferral (DF) for this item. It is not normal for a Supervisor to create a Write-up or DF an item; [that is a] job of a Mechanic or Lead. Technical support Maintenance Control had notified me about this problem through a phone call. I contacted this Mechanic and he said he had talked to some Crew member about this problem; which I had no knowledge about what was talked about. In no way would I dispatch an aircraft with am Emergency Slide Light inoperative. Mechanic had expressed after the fact that he left it up to me what to do! Mechanic had already decided what to do upstairs; talking to crew. There are only two options; fix it or DF it.  Mechanic somehow disregarded both options. Why I am filing this report is because I was notified about this problem and I assumed he [Mechanic] raced back to the Maintenance Room to create a DF for this item. The meaning to me was the Flight crew and the [Mechanic had a] conversation about the Crew was OK with taking this aircraft; that the arming was accomplished and all [that] was needed was a sticker for the DF item. I have no knowledge what was said in the conversation in the aircraft.
A Line Maintenance Supervisor describes how assumptions and a lack of clear communications between himself and a Line Mechanic led to a B757-200 aircraft departing with the Emergency Slide Light inoperative at Door-4R.