The aircraft
Fire protection
Fire detection for both engines and the APU, two extinguisher bottles, and a test switch. What starts a fire, and how to put one out.
Both crew stations have the same fire panel on the glareshield, and either can work it. It needs battery power.
| Control | What it does |
|---|---|
| ENG 1, APU, ENG 2 fire handles | Light red when a fire is detected there. Press to arm that handle: it shuts off fuel to the engine or APU (while there is DC power), the handle’s armed light comes on, and that fire’s voice warning and MASTER WARNING stop. Press again to disarm it. |
| PRI and RES | Discharge the primary or reserve extinguisher bottle into whichever area is armed. Each bottle fires once, and its light shows when it has been used. |
| TEST switch | TEST 1 lights every fire and armed light, plays each fire warning, lights MASTER WARNING and shows DECK FIRE. TEST 2 also lights both bottles’ discharge lights. Return it to the centre to end the test. |
What starts a fire
- Battle damage. A heavy hit on a running engine or a running APU can set it alight. Most hits do not.
- Oil starvation. An engine that fails after losing all its oil pressure catches fire more often than not. See Engines and rotor.
A fire shows as ENGINE 1 FIRE, ENGINE 2 FIRE or APU FIRE, with a voice warning, MASTER WARNING, the handle lit red, and smoke and flame from that side of the aircraft. Every second it burns, it damages the engine or APU further.
Putting it out
- Arm the fire handle for the burning engine or APU. This also shuts off its fuel.
- Press PRI to discharge the primary bottle.
- If the fire is still burning, press RES.
A bottle only reaches a fire if that fire’s handle is already armed when the bottle is discharged. Arm first, then discharge: a bottle fired before the handle is armed, or with only another handle armed, is wasted. A bottle that reaches the fire puts it out, unless it fails: each one has a one-in-four chance of failing, which is what the reserve is for.
With the engine or APU shut down, a fire that is not extinguished usually burns itself out within half a minute or so, still doing damage until it does.
While a fire warning is active, the ENG page shows the immediate action steps.
Arm the handle for the burning side. Arming the wrong one shuts down a good engine. Check the lit handle, or the WCA page, before you press.
The full procedure, including what to do next with one engine, is in Emergency procedures.
Recharging the bottles
Discharged bottles are refilled when the aircraft is repaired.