I was told by a friend who was involved very early on with the DC10 that Douglas had designed a DLC system for it but found it was not required during flight testing so deleted it before the aircraft went into service. He claimed there were diagrams of it in his training notes which the course was told to discard (thankfully according to him as it looked a hideous mechnical arrangement).
I have to agree with cirrus01 earlier about the L1011's maintenance and reliability. The following is something I wrote for a Tristar thread over a year ago but never posted it.
Unfortunately many of the features that delighted flight crews were the very things that plagued the maintenance people especially in the flight controls/autoflight area. The L1011 was an overly complex aircraft for the job it was meant to do. The complex electronics used analogue computer technology except for a few late model aircraft with digital autopilot boxes. The L1011 never achieved the level of maturity that most aircraft arrive at after a few years in service and many systems required too much tender loving care throughout its life whereas other systems started well and got worse with age! Performance of the autoland system easily beat all its contemporaries but was difficult and time consuming to maintain and troubleshoot especially if operating to Cat 2 or 3. The flight controls were a maintenance nightmare as the aircraft aged with numerous wear, friction & bearing failure issues. I have never known an aircraft that experienced as many partial flap/partial slat landings as the L1011. The TE flap system was mechanically complex, lacked robustness, was a lubrication nightmare (try counting the number of grease nipples; about 900 to 1,000 with many hidden) and was prone to jams. The LE Slats suffered control problems as well as some mechanical issues. The flap load relief system never worked reliably and eventually operators were given the option of deactivating it and limiting landing flap to 33 degrees (approach flap) which most gladly did. The numerous rudder control and limiter pressure switches and solenoid valves installed above No. 2 engine were an access problem for line stations. The air-conditioning was woeful in the hot and humid climate in which we operated. The instrument cooling system was inadequate - with round dial engine instruments the centre panel got red-hot affecting instrument reliability. ?Rain in the plane? in the tropics was another never-ending problem with older aircraft. The pressure hull leaked like a sieve and cargo door seals were a notorious problem being easily damaged or pulled out of their retainers by container impact. The APU was hopeless in hot conditions with insufficient output for proper ground cooling or engine starting (at least it was quick and easy to replace). Pneumatic system valves exhibited poor reliability throughout much of the L1011?s life. The fuselage bilge area corroded too easily in a humid environment and there were numerous structural issues, rear spar fatigue at several locations being one of the big ones. The main landing gear experienced a number of major component failures. The toilet system was a headache especially as it aged. Who in his right mind would put a toilet tank, flush pumps and associated plumbing and waste lines in an avionics compartment and then mount the Indicator Light Control Box that controlled every cockpit annunciator light including switchlight flowbars right under the fwd lavs where it could get wet? The Dynatube hydraulic fittings, which were reputedly designed for rockets/missiles, would have best been left on these single use vehicles and not installed on an aircraft where component replacements often resulted in sealing face damage and subsequent difficult-to-fix leaks.
I could go on but the above list is enough to indicate the maintenance guys? frustrations with the Tristar. Our L1011 fleet required 3 times the man-hours to maintain compared to our 747 classics.
It was certainly an interesting aircraft and it definitely provided job security for the engineering and maintenance people but always needed far too much TLC and manhours.
With regard to its limited success (only 250 built) Lockheed originally intended to produce two completely different models; the L1011-1 for domestic use and a similar sized ?2 with 6 wheel MLG bogies like a 777 for long range use, and publicly disparaged the Douglas approach of designing the DC10-30 as a derivative of the ?10 from the very start claiming a dedicated long range model was more efficient. Perhaps so, but in the end Lockheed could not afford to build the ?2 and the shortened ?500 was a shabby compromise with limited sales.