What material is generally used in the construction of aircraft engine firewalls?

• A. Aluminum alloy
• B. Stainless steel
• C. Carbon fiber composite
• D. Titanium nickel alloy

Answer: (D)

When a firewall is built, the primary job is to stop heat and flames from reaching the cabin. That means the material must keep its strength and not react badly under high temperatures for a sustained period. Stainless steel fits this need well because it maintains structural integrity at the elevated temperatures encountered during an engine fire and resists oxidation. Aluminum would lose strength and could fail or melt under those conditions, while carbon fiber composites, though light and strong, can degrade or ignite unless extensive protective measures are used, which adds weight. Titanium-nickel alloys are not typical for firewall use due to cost and their fire resistance characteristics not being as favorable for this specific role. So stainless steel is the practical and reliable choice for engine firewall construction.