The GSE mechanic noticed that the carriage was jammed. I don't know if he moved or maybe even jumped a little or if the carriage decided on its own to let loose. Down went the carriage, arm, and mechanic until the carriage ran out of cable slack and there it suddenly stopped — at least the carriage did. The arm failed under the load of its own weight and inertia. The unfortunate GSE mechanic ended up being badly injured but fortunately, survived.
SO WHAT WENT WRONG?
Post mortems were mainly concerned with pointing fingers. The unit was badly designed. The tension brake had been blamed for causing the jamming. It had contributed, but was not the fault. In the end, the lack of care did it in. The lack of enforcement of the safety program allowed a GSE mechanic to be badly injured. Surely there were enough places to point fingers.
Widebody aircraft are difficult to work on due to their height and size. Brand X recognized this and built a facility to do heavy maintenance checks on their L-1011. Pride of place was given to a docking system that lovingly folded itself around the aircraft when hangared. You could climb up and touch the top of the vertical fin easily. It was an excellent unit in most ways.
When aircraft roll into hangars,the wing stands, etc. must be low enough to allow people to work on them. Then, the aircraft is raised up so that it is now out of reach. The answer, of course, is to adjust the stands, which was done by lots of jackscrews. Torque tubes fitted with universal joints powered them. There were lots of these, too. Still, with everyone clear and watching to make sure nothing on the stand hit anything on the aircraft, it was possible to raise and lower the dock system to the optimum position for work.
Like everything else, the dock system depended on regular maintenance, particularly cleaning jackscrews and lubricating them, while not neglecting universals and angle gearboxes. It was also not a good idea to do paint stripping and washing in the dock either. Paint stripper is unbelievably bad for anything except removing paint. It likes to eat rubber protective boots on jackscrews, too. In a perfect company, all this would have been recognized and a stringent cleaning and lube program would have kept everything in tip-top shape.
Brand X was not a perfect company. The expensive dock system withstood the lack of lubrication care for some time. The day finally came when things jammed. The motors applied their torque to raise or lower the dock platforms. The jackscrews, at least some, were not going to move. The torque built up and the torque tube couplings sheared here and there, some jackscrews turned and changed their height, others didn't. They fortunately stopped before it tore itself apart.
Being too expensive to repair, the dock was laboriously set at a compromised position. Like most compromises, it was not optimum and inevitably hurt production.
It's amazing how much damage a GSE person with some integrity to do the job properly and armed only with a grease gun, an oiler and a sharp set of eyes can prevent. And, how much money can be saved too. A million-dollar piece of GSE is junk if it is not maintained. But hey, you knew that already. Right?
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