Class D compartments and Fire Handles

[The500man]

Am I right in thinking a Class D compartment might be a landing gear bay? The definition I have is that it is a compartment inaccessible by crew that has controllable airflow and is lined with fire resistant material. There is no mention of fire detection or suppressor systems. What other type of compartment might it be?

With regards an engine fire. When using the fire handles to extinguish the fire, handle 1 will fire the explosive cartridge to extinguish a fire in the no. 1 engine. Should the fire persist is there a second setting on fire handle 1 to fire the second bottle or would you use fire handle 2 set to engine no. 1? Would this then preclude you from using fire handle 2 for extinguishing a fire in no. engine 2?

If anyone has a link to how aircraft fire systems actually work that would be awesome!

Thanks.

[Piltdown Man]

Class D Compartments. Have you ever used Ask? (http://www.risingup.com/fars/info/part121-221-FAR.shtml)

Fire Handles: Pull the fire handle to isolate fuel, hydraulics and bleed air but also to set the valves for the extinguishing agent. Twist the handle one way to fire the first bottle and the other way to fire the second.

PM

[The500man]

Hmmm, that link is interesting. It says Class A - D are cargo and baggage compartments, but that is not what my text book says.

Class A - Cockpit and passenger cabin
Class B - Accessible cargo and baggage areas
Class C - Engines
Class D - Inaccessible compartment
Class E - Accessible cargo compartments on cargo only aircraft


Other than common sense is there anything preventing you from firing the extinguisher on the incorrect engine?

[Piltdown Man]

If aircraft's fire warning system has detected the fire, the fire handle should be illuminated.

PM