I'd like to know the difference between a firewall and a bulkhead. They both separate segments of an aircraft, so how are they different as it pertains to their design and purpose in aircraft construction?


A bulkhead is any kind of structural panel separating two spaces in a fuselage. Like a solid panel in the tail cone that has only small holes for cables to pass, or the panel that forms the end of the baggage area. Pretty much any solid lateral partition with a structural use. On a large aircraft, any structural partitions separating parts of the cabin, like the flight deck bulkhead, or terminating the pressure hull at each end, the "pressure bulkheads".

A firewall is a firebreak. It's a bulkhead that is fireproof to separate a "hot" area like an engine compartment from adjacent structure, so that if you have an engine fire, you'll have more time to try to land, or if at high altitude, say your prayers. To be a firewall, the material of the bulkhead has to be flame resistant, with a much higher melting point than aluminum.

On GA airplanes, the firewall is usually stainless steel, but can be galvanized steel (antiques and homebuilts), or even special flame proof coatings on a normal bulkhead (some composite homebuilts). On transport airplanes, a firewall will be stainless or titanium.

So in a nutshell, a bulkhead is a structural lateral panel in a fuselage. A firewall is a "fireproof" bulkhead normally separating the engine compartment (or other flame source) from the rest of the plane.

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    $\begingroup$ This is correct. Ships notably have waterproof bulkheads engineered into their design. The Titanic's waterproof bulkheads were famously not tall enough to be effective in that particular disaster. $\endgroup$ May 25 '20 at 22:49
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    $\begingroup$ I would also like to add that firewalls are NOT fireproof but are there to slow the spread of fire and heat until something can be done with it. They can last a really long time, but they are all rated to fail after "a while" $\endgroup$
    – coteyr
    May 26 '20 at 11:06
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    $\begingroup$ Re read the middle paragraph carefully. $\endgroup$
    – John K
    May 26 '20 at 12:49
  • $\begingroup$ @RobertColumbia Both waterproof ones and fireproof ones, to be precise. Every 40 meters is a mandatory main fire zone, with a keel to top fire-resistant bulkhead. Major bulkheads under the main deck are generally waterproof, above it nothing is. Note how a bulkhead can be waterproof, fireproof, both, or neither. $\endgroup$
    – Therac
    May 26 '20 at 19:52

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