Maintenance Airframe; Maintenance Powerplant
Troubleshooting; Training / Qualification; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Human Factors
[I received] a gate call [on a DC-10] with an air system fail alert on pre-flight air system test. After getting the MEL to do the logbook entry; the circuit breaker would not reset. I collared [the circuit breaker] to prevent anyone else from trying to reset it. After looking into the System Schematic Manual Chapter 21-26-0; I realized that the breaker just controlled the Number 3 fan. I was trying to prevent any further aircraft problems. It also had no history for that discrepancy. I figured the system was inoperative and [that I was] collaring a breaker that would not reset; [so] I just collared it. I collared the breaker just to prevent anyone else from trying to reset. There was no question about safety of flight. I did the research to make sure the breaker did not affect any other components. I should have contacted Maintenance Control. I will contact Maintenance Control and make sure I go by the MEL to the letter and will not deviate. [I will] collect all information and with Maintenance Control; make a decision. Use my resources. I have seen where they put out maintenance alert about this type of problem in the last couple of day. MEL 21-26-05; is a good [reference] to be used if you have a bad cooling fan that fails an operational check; [but] not if the circuit breaker pops.
The Maintenance Technician attempted to comply with the MEL for an avionics cooling fan fault; but discovered that the circuit breaker would not reset. He utilized the MEL and collared the circuit breaker thinking that is was only affecting that fan. By doing so; he did not comply with the approved MEL procedure.