DC-10 Undifferentiated or Other Model
Maintenance Powerplant; Maintenance Airframe
Situational Awareness; Confusion; Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Critical
General Maintenance Action
MEL; Human Factors; Chart Or Publication; Aircraft; Procedure
August 2013; ZZZ Maintenance called in with a Number 2 Flight Control Computer (FCC) faulting the on-side Stick Shaker motor during the Auto Flight System (AFS) Return to Service Check to maintain the Lower Landing Minimums (LLM) status to CAT-3. I talked with the Aircraft Maintenance Technician (AMT) about the fault he was having; and he advised that the Stick Shaker Test passed for the Number 1 FCC. Each FCC will test both stick shakers during their individual AFS tests. He also had an FCC-2 fault; which is deferrable item requiring further troubleshooting and requiring a detailed measurements test for the FCC in question. The Number 2 Autopilot (AP) was placed on MEL 22-10-01 based on the fact that the AFS Test faulted the stick shaker motor during the AFS test only. The FCC was not FAILED; which is a non-deferrable fault. This event developed due to the misinterpretation that the Stick Shaker motor or the FCC was at fault. These items were operational; the stick shakers are tested by both FCC's during the AFS Test. The FCC tests several components that make up the Autopilot and Auto Flight System. If the stick shaker motor was FAILED; then it would not pass the Number 1 FCC AFS Test. If the FCC was FAILED; or the stick shaker motor would not test individually; then using the Autopilot MEL would be incorrect. Maintenance Support. Maintenance Control Manager.
A Maintenance Control Manager explains why an MEL deferral of Number 2 Autopilot on a DC-10 aircraft was allowed with a Number-2 Flight Control Computer (FCC) fault.