2011-12 · NASA ASRS report 986285
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. The Master Caution was caused by a previous MEL deferral of an inoperative low level Annunciator System for the left fuel Collector tank on a Beechcraft 1900 aircraft.
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.
A Beech 1900 aircraft was brought to the hangar due to a log writeup for persistent Master Caution illumination caused by MEL 28-6. I then instructed the mechanics to begin troubleshooting the MEL [deferral]. At XB:00 pm troubleshooting was narrowed down to a connection of a Printed Circuit (PC) board under the cabin floor. Maintenance Control then called and said they needed the aircraft no later than XB:30 pm or they would begin to take cancellations. I instructed the mechanics to then close everything up; but mentioned to Maintenance Control that we still didn't clear the log item. The Maintenance Controller and I (as Maintenance Supervisor) both concluded that with the cannon plug disconnected; no other system would be affected by following the Wiring Diagram Manual. We then documented on the log page and on the Work Card that the [cannon] plug had been disconnected and secured. We then returned the aircraft to service. It was brought to my intention the following day by the Director of Quality Control (DQC) and Director of Maintenance (DOM) that there was no specific manual procedure for removing the cannon plug for this circumstance.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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