The following broadly outlines the refit standards adhered to by Starfleet vessels.
Starfleet divides its vessel refits into three classes; minor, standard and major.
The tasks required for a minor refit would normally be performed by a ship's own
crew, often whilst underway. A standard refit would normally be performed with
the support of a starbase, though larger ships can do at least some of the work
themselves. It should be noted that these standards represent the minimum required
by Starfleet; many chief engineers perform the more minor tasks more frequently
than required, and even more major work such as the swapping out of large components
like bridge modules or warp coils can be performed more often than the specifications
demand if a particular ship is judged to be in need of it.
A major refit would require a dedicated spacedock, and can take in excess of a
year to complete. At its most extreme, this procedure is only a short step away
from building a completely new vessel - the rebuild of the Constitution class
is probably the best example of this kind of major rebuild. Long term proposals
for the Galaxy class also include a major rebuild that would involve the addition
of a third nacelle on the engineering hull and a large "phaser lance"
to the underside of the saucer section, though it is uncertain whether this will
Care must of course be taken when applying Starfleet standards to alien designs.
Starfleet intelligence generally tries to classify the refits vessels belonging
to other powers recieve according to the same scale as the Federation's own ships,
but these should be taken as a guideline only.
||Level one diagnostics performed on the warp and impulse propulsion systems, tactical systems, structural integrity and inertial dampened systems, navigational deflector, life support, computer and sensor systems.
Level two diagnostic performed on all other ship systems.
LCARS software updates integrated into the system.
Rebalancing and recalibration of warp field.
||Level one diagnostic performed on all systems.
Replacement of warp coils, warp core, power conduits, phaser emitter crystals, worn hull plating.
LCARS software updates and comprehensive upgrade of computer hardware.
Addition of non-vital modules such as laboratories, recreational areas, etc.
Swapping out of vital modules such as bridge.
|Can be completed underway, but would generally require starbase support.
||Replacement / rebuild of hull structure - may significantly alter vessel's appearance.
Replacement / reconfiguration of nacelles - may include addition of extra nacelle(s).
General rebuild of systems.
|Requires spacedock support.