Aircraft safety device

An aircraft safety device for explosion-proofing a fuel tank which stores fuel of an aircraft, the fuel tank comprising a ventilation passage that permits ventilation between an inside of the fuel tank and an outside of the fuel tank, the aircraft safety device comprising:

• a flame propagation blocking part which blocks propagation of a flame from the outside of the fuel tank to the inside of the fuel tank through the ventilation passage;
• and
• a gas supply suppressing part which, suppresses a supply of an inflammable gas containing gas of the fuel to the flame through the ventilation passage when the gas supply suppressing part is heated by the flame,
• wherein the gas supply suppressing part comprises:
• a support which constitutes part of the ventilation passage;
• and
• a thermal expansion part which is provided on the inner periphery of the support and is configured to expand when heated by the flame.