> ## Documentation Index
> Fetch the complete documentation index at: https://docs.czautoz.co.uk/llms.txt
> Use this file to discover all available pages before exploring further.

# Damage Zones

> 6 independent damage zones per helicopter — each toggleable. Disable all to make the helicopter fully invincible.

Each helicopter has 6 independent damage zones. Each zone can be individually enabled or disabled per helicopter via its JSON config file. **As of v0.2.2 a disabled zone takes no damage from any source** — gunfire, explosions and collisions alike (previously the toggles only blocked collision damage, so a helicopter with its zones off could still be shot to a wreck). Setting all zones to `0` makes that helicopter completely invincible.

See [Repair & Battery](/features/repair-battery) for repair requirements, hold times, and repair settings.

## The 6 Zones

| Zone Setting           | What it covers       | Effect when destroyed                  |
| ---------------------- | -------------------- | -------------------------------------- |
| `damage.zones.body`    | Fuselage / airframe  | Reduced structural integrity           |
| `damage.zones.engine`  | Engine               | Engine failure, forced autorotation    |
| `damage.zones.chassis` | Landing gear / skids | Loss of stable ground contact          |
| `damage.zones.fuel`    | Fuel tank            | Increased fuel leak rate               |
| `damage.zones.rotor1`  | Main rotor           | **Helicopter falls — immediate crash** |
| `damage.zones.rotor2`  | Tail rotor           | **Uncontrolled yaw spin**              |

## Defaults

| Helicopter                 | Chassis | Body | Engine | Fuel | Main Rotor | Tail Rotor |
| -------------------------- | ------- | ---- | ------ | ---- | ---------- | ---------- |
| MD500, MH-6, SA342M, UH-1H | 0       | 1    | 1      | 1    | 1          | 1          |
| MH-60L Blackhawk           | 1       | 1    | 1      | 1    | 1          | 1          |
| AW101 Merlin               | 1       | 1    | 1      | 1    | 1          | 1          |

Skid-equipped helicopters have chassis damage disabled by default. Wheeled helicopters (Blackhawk, Merlin) have it enabled.

## Zone Health Levels & HUD Indicators

Each damage zone progresses through four states, shown as colour-coded indicators on the in-cockpit HUD:

| Level | HUD Colour | Condition                            |
| ----- | ---------- | ------------------------------------ |
| 0     | **White**  | Undamaged                            |
| 1     | **Yellow** | Light damage (\~75% HP remaining)    |
| 2     | **Amber**  | Heavy damage (\~55% HP remaining)    |
| 3     | **Red**    | Critical damage (\~35% HP remaining) |
| 4     | —          | **Destroyed** — zone is inoperable   |

Zone repair is progressive — each repair hold advances the zone one level upward (e.g. Red → Amber). A critically damaged zone requires multiple repair actions to fully restore.

***

## Rotor Damage

### Main Rotor Destroyed

The helicopter immediately loses lift and falls. There is no recovery.

### Tail Rotor Destroyed

The helicopter enters an uncontrolled yaw spin. Spin rate is set by `tailRotorFailure.spinRate` and a forced descent is applied at `tailRotorFailure.descentRate`.

| Setting                        | Default (all helicopters) |
| ------------------------------ | ------------------------- |
| `tailRotorFailure.spinRate`    | 120 deg/s                 |
| `tailRotorFailure.descentRate` | 2.5 m/s²                  |

These are the uniform defaults across all six helicopters and are editable per variant in each helicopter's JSON config.

## Rotor Blade Shear

Rotor blades can shear off on contact with geometry (trees, buildings, terrain):

| Setting                    | Default                                        |
| -------------------------- | ---------------------------------------------- |
| `features.rotorBladeShear` | `1` = blades shear on contact · `0` = no shear |

## Rotor Disc Collision & Player Kill

| Setting                           | What it does                                                      | Default |
| --------------------------------- | ----------------------------------------------------------------- | ------- |
| `features.rotorDiscCollision`     | `1` = spinning rotor disc has physical collision                  | `1`     |
| `features.rotorPlayerKillEnabled` | `1` = players entering a spinning rotor disc are instantly killed | `1`     |

<Note>
  Blade shear and the rotor-disc player kill are global toggles under the `features` section of `mod_config.json`, not per-helicopter JSON. The spinning disc is sampled from the rotor's centre and tip memory points rather than the model's collision geometry, making strike detection cheaper and more reliable.
</Note>

## Making a Helicopter Invincible

Set all 6 zone values to `0` inside the `damage.zones` section of the helicopter's JSON config file:

```json theme={null}
"damage": {
  "zones": {
    "chassis": 0,
    "body": 0,
    "engine": 0,
    "fuel": 0,
    "rotor1": 0,
    "rotor2": 0
  }
}
```

## Rotors-Only Damage

Enable **only** the rotor zones and disable the rest — the rotors can be shot or damaged (they degrade and shear) while the **hull stays invulnerable**. This is ideal for servers running AI that fire on helicopters: gunfire knocks out the rotors (costing lift and control) without ever destroying the airframe.

```json theme={null}
"damage": {
  "zones": {
    "chassis": 0,
    "body": 0,
    "engine": 0,
    "fuel": 0,
    "rotor1": 1,
    "rotor2": 1
  }
}
```

Rotor damage never transfers to the airframe's overall health, so a rotors-only helicopter can be forced down but not blown up.

## Ruined Parts Fall Off

When `damage.detachRuinedParts` is enabled, a door (or any attachment) that becomes **ruined detaches and drops off the helicopter** onto the ground, instead of sitting ruined in its slot. Default off.

| Setting                    | What it does                                                                             | Default |
| -------------------------- | ---------------------------------------------------------------------------------------- | ------- |
| `damage.detachRuinedParts` | `1` = ruined doors/attachments fall off the helicopter · `0` = they stay ruined in place | `0`     |

## Impact Damage

| Setting                           | What it does                                                      | Default                                                                                |
| --------------------------------- | ----------------------------------------------------------------- | -------------------------------------------------------------------------------------- |
| `damage.contactCoef`              | Impact damage multiplier — lower = tougher airframe               | Per-helicopter — see [Per-Helicopter Settings](/server-config/per-helicopter-settings) |
| `damage.crashThreshold`           | Impact sensitivity — higher = harder hits needed for heavy damage | Per-helicopter — see [Per-Helicopter Settings](/server-config/per-helicopter-settings) |
| `damage.playerCrashDamageEnabled` | `1` = crew take HP damage on hard impacts (per helicopter)        | `0`                                                                                    |
| `gameplay.playerCrashDamageMax`   | Max HP damage per impact — global setting in `mod_config.json`    | `75`                                                                                   |

<Note>
  Crash and hard water-impact damage now also applies to players **moving in the cabin or standing on the airframe**, not only those buckled into a cockpit or cargo seat.
</Note>

***

## Wreck Fire

When a helicopter is destroyed, it catches fire and burns for a configurable time — a flickering fire light plus a **fire-damage area that hurts players standing too close**. The fire is suppressed underwater, and a destroyed wreck will not re-ignite if shot again.

| Setting                | What it does                                                                      | Default |
| ---------------------- | --------------------------------------------------------------------------------- | ------- |
| `damage.burn.duration` | How long the wreck burns, in seconds. Set to `0` to fully disable the wreck fire. | `120.0` |
| `damage.burn.radius`   | Radius of the fire-damage area, in metres                                         | `8.0`   |

Both keys live in the `damage.burn` section of each helicopter's JSON config, so burn time and area can be tuned per variant.

<Note>
  Setting `damage.burn.duration = 0` **fully disables the wreck fire** — no fire or smoke particle, no fire light, and no area damage. A destroyed helicopter simply becomes a static wreck.
</Note>