A puff back that is caused by an accumulation of air-oil mixture in the combustion chamber that is ignited either a late spark or the hot refractory material results in what?

• A. smoke
• B. backfire
• C. explosion
• D. fireball

Answer: (C)

Puff back is the rapid ignition of an accumulated air-oil mixture inside the combustion chamber, caused by a late spark or hot refractory. When that trapped mixture ignites, energy is released violently inside the chamber, producing an explosion. This is different from smoke (incomplete combustion) or a backfire (flame moving back toward the fuel supply), and while a fireball can occur, the defining result of puff back is an internal explosion.