However I have come across many different opinions :
- some say always immediately select max. thrust to improve climb performance
- some say leave the thrust as it is, to avoid destabilising the aircraft, and then perhaps add aditional thrust (if required) once the autopilot is on
I suppose these are all acceptable techniques, however some also say :
- don't ever increase thrust if an engine fire (don't add fuel to the fire)
whilst others say
- it's ok to increase thrust (on both engines) even if an engine fire
John, you may be confusing different events or scenarios.
Given a power loss, engine fire, failure, or other problem after V1, in which the airplane is still going flying (given that insufficient room remains to reject the takeoff), one is going to continue using the thrust with which the takeoff has been planned, and briefed.
A reduced thrust takeoff, as others have noted, takes into account performance with an engine loss. The speeds that are calculated are crafted with this in mind, and the performance that remains with an engine lost. The rejection numbers are applied accordingly. Add thrust, and one may very well have a dangerous condition, especially at low speeds during the initial takeoff. The best course of action is to leave everything alone, climb to a minimum safe height, begin to clean up...and during that time one can apply maximum continuous thrust, run checklists, etc.
If one has an engine fire on takeoff without any thrust loss, why on earth would one want to increase thrust or need to do so? That makes no sense.
If an engine fire occurs during the takeoff at a point where stopping is no longer an option, then the same procedure occurs. Climb, get to a safe altitude to configure and run checklists, then handle the emergency. Unless actual control of the aircraft is threatened, then one has a singular priority during the takeoff; maintain control of the airplane, and fly it to a safe altitude. Only after that has been accomplished does one begin changing airplane configuration, power settings, or addressing the emergency.
As always, fly the airplane first.