L-1011 ($2.5 billion in the hole).
If I am remembering correctly a lot of Lockheed's troubles with the 1011 arose when the RB-211 did not work with the composite materials that were planned for the fan blades.
I believe that problem cost RR a bundle, (and perhaps the UK taxpayers ??) and gave Lockheed a big problem.
I spent some time on the L-1011, primarily the -500 and I thought it was probably the aircraft I enjoyed the most in my time. Not just for the flight crew but the cabin layout we had was something I have not seen since. F/C at least.