Narrative:

December 2011; a beech 1900 aircraft had an MEL 28-6 (left collector tank low; annunciator system inoperative) item open; and a logbook writeup added: 'captain determined aircraft is unsuitable for continued flight due to persistent master caution illumination caused by MEL 28-6'. I swapped the line of flight to another aircraft and had maintenance taxi the beech 1900 from the terminal to the hangar for further troubleshooting.[maintenance] troubleshooting narrowed the problem down to the connection of the cannon plug P417 and the low level sensor E130 and verified that when disconnected; the master caution would no longer be triggered. The maintenance supervisor and I both concluded that with the cannon plug [P417] disconnected; no other system would be affected by following the manufacturers wiring diagram. We then documented on the log page and on the referenced non-routine work card that the cannon plug had been disconnected and secured. We then returned the aircraft to service. Captain X refused the aircraft as it was at xb:40 pm. Captain Y accepted the aircraft as it was at xc:00 pm. The following day; I was called by the director of maintenance (dom) and told to resecure the cannon plug that had been previously removed before any more flights occurred. I complied and had the line mechanic at ZZZ1 re-install the cannon plug and generate a non-routine card to document [the reinstallation]. The aircraft then departed with a 30-minute delay. The director of quality control (dqc) then informed me of the reasons for the reinstall [of the canon plug] being that there was no specific manual procedure for removing the cannon plug for this circumstance.

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Original NASA ASRS Text

Title: A Maintenance Controller and Maintenance Supervisor were told to have Maintenance re-connect a cannon plug they had authorized to be disconnected to stop a persistent Master Caution illumination; caused by a previous MEL deferral of an inoperative low level Annunciator System for the left fuel Collector tank on a Beechcraft 1900 aircraft.

Narrative: December 2011; a Beech 1900 aircraft had an MEL 28-6 (left collector tank low; Annunciator System inoperative) item open; and a logbook writeup added: 'Captain determined aircraft is unsuitable for continued flight due to persistent Master Caution illumination caused by MEL 28-6'. I swapped the line of flight to another aircraft and had Maintenance taxi the Beech 1900 from the terminal to the hangar for further troubleshooting.[Maintenance] troubleshooting narrowed the problem down to the connection of the cannon plug P417 and the Low Level Sensor E130 and verified that when disconnected; the Master Caution would no longer be triggered. The Maintenance Supervisor and I both concluded that with the cannon plug [P417] disconnected; no other system would be affected by following the Manufacturers wiring diagram. We then documented on the log page and on the referenced Non-Routine Work Card that the cannon plug had been disconnected and secured. We then returned the aircraft to service. Captain X refused the aircraft as it was at XB:40 pm. Captain Y accepted the aircraft as it was at XC:00 pm. The following day; I was called by the Director of Maintenance (DOM) and told to resecure the cannon plug that had been previously removed before any more flights occurred. I complied and had the Line Mechanic at ZZZ1 re-install the cannon plug and generate a Non-Routine Card to document [the reinstallation]. The aircraft then departed with a 30-minute delay. The Director of Quality Control (DQC) then informed me of the reasons for the reinstall [of the canon plug] being that there was no specific manual procedure for removing the cannon plug for this circumstance.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.