So what exactly was u/s?
Fire and Overheat Detection and Extinguishing system for the engines or Smoke Detection and Extinguishing for the cargo compartments?
I guess that it is not really the point of the thread, but anyway, here also the MEL for the Engines fire protection. 
In this case the rectification interval is C, 10 days!
26-12 ENGINE FIRE AND OVERHEAT DETECTION
12-01 Fire Detection System
A) Detection Loop A
C 2 0 Except for ER operations beyond 120
minutes, one may be inoperative on each
engine provided :
1) Associated detection loop B is
operative, and
2) The engine fire test is made before
each flight.
B) Detection Loop B
C 2 0 Except for ER operations beyond 120
minutes, one may be inoperative on each
engine provided the engine fire test is
made before each flight.