MINIMUM EQUIPMENT LIST IN ERROR.

Narrative

THIS PROB AROSE BECAUSE OF AN INACCURATE MEL. WE WERE SCHEDULED TO FLY AN LGT FROM DTW TO MIA; AND WHILE REVIEWING THE ACFT LOGBOOK; NOTICED A DEFERRED ITEM THAT REQUIRED ADDITIONAL RESEARCH. THAT DEFERRED ITEM WAS AN INOP AUX VERT GYRO. WE CHKED THE MEL IN THE LGT MANUAL AND FOUND THAT IT INDICATED; ERRONEOUSLY; THAT 2 GYROS ARE INSTALLED AND REQUIRED FOR FLT. THE FACT IS THAT 3 GYROS ARE INSTALLED; CAPT'S; FO'S AND THE AUX. WE CONTACTED OUR DISPATCHER AND MAINT CTL AND WERE ASSURED THAT ALL THAT WAS REQUIRED WERE 2 GYROS WITH SEPARATE PWR SOURCES; WHICH WE HAD. THE WX WAS GOOD DURING ALL REGIMES OF FLT AND WE ELECTED TO ACCEPT THE ACFT. ACCORDING TO OUR MEL; IF NO MENTION IS MADE OF A COMPONENT; IT IS A REQUIRED; NO-GO ITEM. OBVIOUSLY IN THIS CASE; THE MEL IS IN ERROR BY SHOWING THE INSTALLATION OF ONLY 2 GYROS; WHEN IN FACT 3 ARE INSTALLED; EACH WITH SEPARATE PWR SOURCES. IN OUR JUDGEMENT; THE MEL IS IN ERROR. NO DANGER TO THE FLT EXISTED AND THE FLT COULD AND SHOULD HAVE BEEN CONTINUED. OUR FAA APPROVED; COMPANY WRITTEN MEL SHOULD BE CORRECTED. ALSO; ON THE FOLLOWING DAY; FLT FROM TPA TO MEM; DIFFERENT SHIP; THE EXACT SITUATION RECURRED.