True That The B-36 Needs 336 Spark Plugs Changed Every Time It Came In For Service?

A long-running question among aviation enthusiasts—whether every service visit to the Convair B-36 Peacemaker required changing all 336 spark plugs—turns out to be a mix of accurate math and exaggerated claims. The figure is arithmetically correct for the aircraft’s six Pratt & Whitney R-4360 Wasp Major radial engines, each with 28 cylinders arranged in four rows and two spark plugs per cylinder, totaling 336 plugs per airframe. However, Strategic Air Command rules didn’t mandate replacing the entire ignition set after short routine flights. After longer endurance missions of 24 to 40 hours, mechanics often swapped the full set due to lead buildup and heat degradation. Replacement decisions depended on operating conditions rather than a fixed calendar.