How many serious airline accidents have been caused by design faults alone? That is, in the chain of events that led to death or injuries in an airline accident, how often has a design fault been solely responsible?

By a design fault I mean a problem such that even if the equipment: 


were maintained and operated to the highest possible standards
flown in ideal conditions 
by pilots who committed no errors
unaffected by manufacturing defects
endured no bad luck


eventually it would still inevitably eventually kill or injure its passengers.

I can think of only two examples: the early Comet's square windows, and the Boeing 737 rudder power control problem.

All the others I can think of include errors of piloting, manufacture, maintenance or just plain bad luck in the chain of causes.

Are there others?
The Douglas DC-10 - The door latching mechanism was not robust and the design of the safety indication was flawed. In the Paris incident Douglas tried to blame the handler who closed the bulk compartment door for using excessive force when latching the door but ultimately the design was at fault.