Date: 201404
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737-300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Parked
Aircraft component: Powerplant Fire/Overheat Warning
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Human-Machine Interface
Second reporter function: First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action
Contributing factors: Human Factors; Company Policy; Aircraft; Procedure
Primary problem: Procedure

Narrative: While doing the Fire Warning Overheat Test during preflight; we noticed an anomaly during the test. During the fire test while pressing the fire bell horn cutout; the bell silenced and immediately came back on. We silenced the bell and it immediately returned again. We tried the test again with the same results using the bell cutout in the fire handle quadrant. We called Maintenance out. The Mechanic came out and we showed him the test. He said that this was a normal indication for the test. When the First Officer; who was a seasoned Captain from another carrier; and I questioned the Mechanic about this; he said he would call Maintenance Control. One minute later; he came back and said Maintenance Control agreed that nothing was wrong. We left and discussed this enroute and felt we had been misled to take this aircraft. After landing at XXX; I performed the test and could not duplicate the same test results. I personally called Maintenance Control and came away from that conversation that we were indeed misled by the Mechanic. While we could not duplicate the same test results in [our destination]; we feel that airplane should have been looked at in [at our departure airport] instead of discarding our observation chalked up to lack of proper test indications. I firmly believe this Mechanic either lacked basic knowledge of the system or misled us into making us believe we lacked system knowledge so we would take an airplane that otherwise might have been grounded. I will put everything in the book and also call the Chief Pilot on Duty when I face a similar situation in the future.


Second narrative: Both the Captain and I explained that we had conducted this test numerous times before and that we did not think the test result was normal. He again said that we were not conducting a proper test and assured us the fire warning system was operating properly.Direct communication between the pilot in command and Maintenance Control is imperative to ensure that everyone is on the same page and understands all the concerns.


Synopsis: Both pilots of a B737-300 believed the engine fire warning test had been invalid because; although the warning bell would properly cease when the cutout button was pressed; it would come back on immediately upon release of the button. The Mechanic; who felt the test was normal; advised he had contacted Maintenance Control who had agreed with him it was a normal test. The flight crew ultimately agreed to take the aircraft; but in the end; decided Maintenance Control was incorrect and submitted the report.