ACS was invented for the -500 so they could extend the span without beefing up the wing.
Partially true, ACS was used on the C-5 first and adapted to use on the -500.
I remember having to hand fly it 4 hours from mid artlantic because the overhead panel resembled a 12 volt christmas tree operating on 24 volts.At least 3 of the QRH checks said "hand fly and land at nearest suitable".
What a dirty rotten shame, you actually had to do your job for 4 whole hours!
The 1011 was too clever by half and so complex it was a maintenance man's nightmare.
Only if the maintenance man had less than average skill!
The chief pilot at an operator that flew both the L-1011 and the DC-10 explained the difference between the two this way: It takes a little more effort the get the L-1011 in the air. But once it is in the air I realize that any extra effort was more than worth it.
I am still waiting for Golden Rivit to tell me where the 7075-T6, that has caused the most of the TriStars to be parked, is located.