According to Rudy Opitz: 1. Rocket engines would explode without warning.
Rudy Opitz: engines were reliable and relatively safe and were adjusted so as to shut down in the event of an imbalance in fuel flow. If there was a problem in engine performance, it related to shutdowns, not explosions. The only instances of engines blowing were in early testing of prototypes or when they had been damaged in battle or by accident.
2. Leaking fuel could turn pilots to jelly, particularly if the plane flipped over.
RO: pilots, me included, survived overturned Komets, and an overturned ship would not necessarily leak fuel into the cockpit. When fuel contacted organic material, including skin, it ignited after only a few seconds. Our protective nylon suits would not ignite but were porous, and fuel could sop through to the skin.
Landing accidents tended to be from the pilot coming in too fast, or too hard, damaging the plane... but this would happen to any plane if it came in too fast or touched down too hard (unless it was a carrier launched plane).
Random explosions due to fuel being bumped around is a myth.. it would require the two fuels to mix to react.
-SW