From a maintenance point of view, computerizing the whole airplane brings certain disadvantages, like increased software hiccups and other, not reproducable faults. The MD
-11 uses the old DC-10 (DC-3, DC-4....) flight control system running with cables. Once rigged, normaly no problem.
I´ve got to say it is basically a good design, but the MD
-11 suffers from poor workmanship and sloppiness. It could be that the workers at MD
were not really motivated during the last few years and didn´t do their work properly. So there are a lot of problems concerning routing of wires and tubes (parts chafing against each other, causing breaks, shorts and leaks). LH
Cargo had a big problem with this because they got the last MD
-11s, when all workers already had a notice in their pockets, telling them that their jobs would be terminated once the last MD
-11 leaves the factory.
Another thing is the design philosophy. It requires a different mindset than Boeing or Airbus. In the airline I´m working for many mechanics come from Boeing products and refuse to learn the philosophy of MD
. This leads to bad troubleshooting results and delays. Instead they just gripe about the f*cking MD
If you set your mind to this plane, it is really easy to handle. I rarely have maintenance delaysm, because most problems can be fixed by just reseting the right C/B, and even if you have to change something, access on the MD
with the exception of the top of #2 engine is very good, all access panels have quick release fasteners, compared to Boeing, where you usually have to drill out 50 screws with rounded heads.
T/s through the CFDS (Centralised Fault Detection System) is easy as well, once you got the knack.
Concerning the smaller horizontal stabilizer, like most planes today it acts as a trim tank. You don´t need as much (drag increasing) surface, because the Fuel System Controller (FSC) pumps fuel into it for weight and balance purposes.
Another thing is to increase efficiency, the MD
-11 flies almost horizontaly in cruise, not nose up like most other airplanes (causing extra drag).
This makes it a little instable around the pitch axis. To keep it stable it uses a LSAS (Longitudinal Stability Augmentation System) in the Flight Control Computers (FCC), which works like a yaw damper, but around the pitch axis.