Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Human-Machine Interface; Confusion; Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Maintenance Action
Aircraft; Human Factors; Logbook Entry; Procedure
After engine start; as the First Officer ran the Before Taxi Checklist; only eleven of the twelve system lights illuminated during the 'RECALL …CHECK' item. The engine light did not illuminate. We advised Ramp Control that we needed to hold our position while we consulted the MEL. The pertinent MEL states that 11 of 12 System Annunciators are required for dispatch and directs the flight crew to: A. check that associated system indicator lights on associated panel are operative. B. If the MASTER CAUTION light illuminates with none of the system lights illuminated; it can be assured that the system with the placarded light is affected. C. Just prior to descent; check the associated panel for any light indications associated with the inoperative system indicator light. As I observed the Engine Panel in the over-head; I pondered how I could check the associated Engine System indicator lights were actually operational (not just tested). If; for instance; it had been a Hydraulic System six-pack indicator light issue; I could have turned off a hydraulic pump and caused the MASTER CAUTION light; the hydraulic six-pack indicator light and low pressure light on the overhead panel to illuminate; etc. However; to check an Engine System indicator light (i.e. reversers) was operational I would have had to shutdown the engine and deployed the thrust reversers.Since; this was not a part of the operations/procedures; I called Maintenance. Once I described the issue; Maintenance said I needed to return to the gate so they could reset some circuit breakers. Maintenance reset of the circuit breakers (3 times) was unsuccessful. The mechanic did a Lights Test; the six-pack engine light still did not illuminate; however the Engine System panel lights in the overhead (Reversers; Engine Controls) did illuminate. He said that met the requirements for an operational check. Though I voiced concern that steps A and B. above were not met in that an Engine System panel discrete light did not cause the MASTER CAUTION to illuminate; he said it met the requirements; and placarded the engine six-pack inoperative. In addition there had been two previous write-ups and placarding of the six-pack engine system indicator. Also during the Before Landing Checklist; recall; all 12 six-pack system lights illuminated normally. I placed an 'Info to Maintenance' item in the logbook describing the same. The long explanation is to get to this question; did I interpret the MEL language correctly? Or; is a Lights Test sufficient to meet the wording of MEL 33-15 to check the associated system indicator light(s) on associated panel is operative? I believe MEL 33-15 should also have a (M) Procedures since the flight crew cannot check all the associated panels (for the 12 Six Pack System Annunciator Lights) indicator lights are operational.
A B737NG Captain expressed concern about the proper interpretation of an MEL regarding malfunctioning flight crew alerting systems.