V-T-1 - Common rail ruptures aren't unknown, and when they rupture, it's extremely dangerous. Fuel spraying everywhere, over a hot engine, at 20,000-30,000 psi, is a guaranteed way to start a major fire.
It's often a catastrophic event on ships and construction equipment, resulting in major fires. On a aircraft, it would immediately be life-threatening.
It's not a problem that is going to stop diesels in aircraft, it just needs to be addressed in the design of the fuel injection equipment, if extremely high pressure common-rail injection is planned to be used.