FCOM - Fire warnings
If I were drafting the FCOM chapter on 'Engine Fire in Flight' it would probably look something like this.
As per the QRH as far as 'Confirm Engine Fire'. Then I would add a line that says;
Fire warnings may disappear after selecting EMS to 'idle'. If this occurs suspect hot gas leak. Situation may still be hazardous, LAND AS SOON AS POSSIBLE anywhere nearby suitable for OEI landing using lowest achievable ground speed if surface is unprepared or space limited.
If fire warnings remain illuminated then use the following as guidance. The aircraft commander may do whatever he feels appropriate to protect the lives of his crew and passengers bearing in mind the wide range of possible failure modes he may encounter.
Guidelines for dealing with continuing indications of engine fire.
If circumstances are benign (day, VMC),
1. Confirm appropriate ECL then select it to IDLE, then OFF
2. Arm appropriate fire extinguisher using the 'ARM' button taking care to select correct button.
3. Select FIRE BOTTLE to 'BOTTLE 1', start stopwatch.
4. After 45 seconds if fire warnings persist then select FIRE BOTTLE to 'BOTTLE 2'.
5. If fire warnings remain on there are other indications that a genuine fire exists then LAND IMMEDIATELY.
OR
If fire warnings persist and there are no other indications that a genuine fires exists then LAND AS SOON AS POSSIBLE. Monitor the situation closely for signs that the fire was genuine after all and LAND IMMEDIATELY.
If circumstances are critical (night or IMC with no hope of achieving VMC above the MSA) then consideration must be based on a risk assessment with the commander choosing what he believes to be the course of action with the least risk. His options are;
1. Continue flight and LAND AS SOON AS POSSIBLE at the nearest suitable IFR airport.
2. Descend to achieve VMC and continue to immediate OEI landing if terrain permits or LAND AS SOON AS POSSIBLE at the nearest available and suitable aviation facility.
If after carrying out the fire drill above there are definite signs of fire but the possibility of a safe immediate landing is remote due to the possibility of CFIT then LAND AS SOON AS POSSIBLE at the nearest suitable IFR airport.
If circumstances are severe due to uncontrolled extensive on board conflagration then LAND IMMEDIATELY and attempt to use the navigation facilities available to descend into an area where it may be possible to achieve VMC.
Comments, suggestions welcome.
G.