The Devil in the detail

Dishwashers, Jets and Taxis

The handle that opens the dishwasher door broke off today. It almost scrapped the machine. If you can’t open the door, it is useless scrap metal.

The internal structures and rotors of the washer fight corrosion and stress throughout its life. Even when it is stopped and not in use: no – ESPECIALLY when it is stopped. That’s corrosion. A lot of engineering effort have gone into these internals and the outer, white-enamelled shell.

It happens time and time again to engineers. The team works hard to get the core of the machine right. At the end, the team leader sighs, ‘Phew!’, she says ‘Well done, guys’. What happens then? Something outside the core goes wrong, that’s what.

In the handle mechanism, there are steel links to take quite high latching loads. On one link is mounted a plastic moulding for the fingers which clearly has some bending in it. It broke; so too much it seems. Or it’s just old-age perhaps.

Anyway, now with strong fingers, you can still move the bare linkage and open the door. With weak fingers though, the door stays locked and you are done for. It is a machine still just working– but getting close to useless.

It happens all the time; sometimes more painfully than when it is on a dishwasher.

trent 900 turbine end
Turbine end of a gas-turbine engine where fire & explosion took place

There was a small component once on a new design of £multi-million aero gas-turbine. It had just gone into service. It was festooned with the good results of testing that had cost many, many more £millions. The component probably cost about 0.001% or less of the cost of the whole engine. One machining process in the part was badly controlled. Cracks appeared. The component failed. Oil leaked out and caught fire in the engine. The turbine exploded in flight and nearly brought down the plane with all its passengers. All the engines – and their aircraft – had to be grounded. The cost was a fortune in treasure and reputation.

The jet engine company survived the cost of the problem but a taxi steering box problem bankrupted its maker.

The London Taxi Company had been struggling with financial losses for some years. Then came a serious problem with the steering box. The detail of the problem was never made public. Now the cost of the steering box is only a very small proportion of the cost of a black taxi compared to the engine and body. It is, though, a vital safety assembly in that it is a link in the steering system.

When the problem was found to be present in taxis on the road, many hundred had to be recalled and repaired at the expense of the London Taxi Company. The financial burden of this process drove the Company into administration and most of the workers lost their jobs. After a few months of suspense and, no doubt, negotiation a Chinese car firm, Geely, bought it out.

The original manufacturer in the UK of the steering box claimed that the problem arose in the box only when it was taken away and out-sourced to, strangely enough, China. When the manufacture was repatriated to the UK [back to him, the original, of course] the problem went away.

The engineering devil is ALWAYS in the detail.

The eternal problem for the engineer is ‘How do I think of what I have not thought of?’

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