From Mechwarrior Living Legends Wiki
All Mechs, Vehicles, and Air Assets may be repaired at their associated Hangars. The Vehicles and Mechs must be placed mostly in a Hangar Bay, Aeros must place at least the tip of their nose in the Aero Hangar, and VTOLs must be landed on any part of the VTOL Platform, Battle Armors have self-repair which begins after short period of time after taking last damage.
Once completely stopped in the appropriate place, the player must Power Down the unit (the [p] key), which will initiate Repairs. Cbills will be deducted while repairs are in progress, and repairs will be halted if the unit is Powered Up before repairs are complete, if player runs out of Cbills, or if repairs are finished. Upon successfully repairing the unit, the player may Power Up and exit the Hangar.
Repairing is a cheap way of extending unit lifespan on battlefield, very often more profitable than death. It's especially critical in Test of Strength mode where each Cbill counts more. Note that although repairs cannot restore completely destroyed arms or shoulders (or legs!), Mechs without weaponry in a part can lose that part without having its firepower permanently reduced. For example, the Hollander II A's weaponry consists of a single Heavy Gauss mounted on the right shoulder, so it could suffer the loss of both arms and the left shoulder without its firepower being affected (granted, it will be somewhat easier to destroy without the limbs and shoulder shielding its center torso, and will suffer critical damage to the center torso when hit in the destroyed shoulder).
- Restore Armor values to full (or, as close to full as you can afford)
- Replace lost cockpit or back armor
- Repair a damaged engine (back armor)
- Refill Coolant
- Restore weapons that were disabled, provided the part they were attached to was not completely destroyed
Repairs will not:
- Replace lost arms, shoulders, legs or other Mech parts other than head or back
- Restore components lost when the Mech part they were attached to was destroyed
- Reload ammo-based Weapons; ammunition may be purchased separately while near repair facilities