Worked with Tristars with RB211 524 in Saudi then with 22B - Every pilot that flew them loved them. To maintain them was a different story - required much more attention than a 747,accessibility was poor,hydraulic fittings a nightmare. The APU was an abortion and did not like high ambient temperatures. Pneumatic ducting was fragile and they required a large spares holding. Did more gear swings (retraction tests) than with any other aircraft - usually after a phase control valve change. A very comfortable aircraft to fly in but why anybody would want to operate them now I do not know. If they do get into service it will not be for long.