The Automatic Test Rig

"What automatic test rig?" asked the Chief Designer when I told him it was the source of a serious problem uncovered by one of our main customers, BEA/BOAC no less. (Now British Airways, of course). That question told me I had an even bigger problem: The Automatic Test Rig had been the pet concept of my new departmental boss, a man I had never seen: a man reported to be a close friend of the Managing Director, and who had remained shut in his office for all of his six-months in the position and, as far as I could tell, had only been seen by one or two of the old hands in the department.

It looked like a repeat of the RAF Maxaret problems, but with a difference. BEA and BOAC had their own Approved maintenance facility for Dunlop equipment, and as long as I had been there Maxarets of both types serviced by BEA/BOAC had landed on my desk with almost monotonous regularity, a "Failed test" tag attached. The response was always the same. I sent them off for test, and they came back with a clean bill of health. One day I was summoned to the office of the Chief Designer who asked me to accompany the Assistant Chief Designer to BEA Maintenance at Heathrow and find out what was going on. On arrival my friend had his own business to attend to, so I was dropped off at the Maintenance shop and left to deal with the matter. I had with me one of the errant BEA-serviced Maxarets given a clean bill of health by the Dunlop test house. This was handed over and loaded into the Dunlop Portable Test Rig they used there - the first time I had ever seen such a device, about the size of a modern built-in cooker cabinet on wheels. As far as I could see, they all knew what they were doing and I couldn't fault their procedure.  However, the moment the machine was fired up and the brake pedal pressed, the problem became clear to me. The answer lay in the pressure response. The portable test rig performed exactly as intended: BANG! Pressure ON brakes on. Bang! Pressure OFF brakes off. BANG! Pressure ON brakes on. BANG! Pressure OFF brakes off.... and so on, a square-wave response exactly as the designer intended.  The difference between the factory test rigs, gradually loaded up over the years with well-intentioned assorted pressure gauges and monitoring devices was stark. The factory test rigs sighed UUUP and then sighed DOOOWN. They certainly no longer had a square-wave response, and the properties of the springs that controlled the ON/OFF response had gradually been modified unofficially to suit the factory test rigs.

I had learned, by then, to keep my thoughts to myself until the picture was clearer, so I gave a non-committal report of the day to my taxi driver friend from the design department, but hatched a cunning plan to shed more light on the matter.

The following day I took the errant Maxaret to my gliding friend Jim's test house and asked that it be tested on every one of the rigs in use, whatever the fluid they used. We were going to throw away the old seals anyway, so the only requirement was to ensure the device was properly cleaned before moving on to the next rig.  The end of the day produced an interesting result. Every single test rig performed significantly differently, and the worst one of the lot was - you might have guessed it - the new unauthorised automatic test rig designed and funded by my new departmental boss.

I knew then that my time at Dunlop Aviation was coming to an end. Collectively we had achieved our objective in reducing the scrap-rate to an acceptable figure, and it was more than likely that many of us would go, not least because Harold Wilson's White Heat of Technology had begun to blow and Britain's economy was taking a dive. We had already seen a devaluation of the Pound. ("This doesn't mean the pound in your pocket is worth less" he told the nation on television.  "Oh yes it does." we all replied in unison). I was in a quandary. Should I seek an audience with my new boss and tell him I had shopped him, or request to see his friend the MD and tell him the same story? My best bet would have been to ring BEA in London and ask for a job on the basis of knowing where all the bodies were buried, but before I did that, something better turned up, opening the door to a new adventure overseas.

The Beginning of the End

The success with the Rim Maxaret was tempered by a dismal failure very soon after. In retrospect it was a clear set-up, probably best described as a bad joke that might have looked funny from someone else's perspective, but didn't look good for me when the concealed facts were revealed. Typical  big company politics...

 One day an apparently brand-new, unused brake disc landed on my desk with a terse note that it was "Too big". Out came the drawings and, yes, the diameter was 10mm greater than it should have been. The first journey was down to the inspection section where it was shown to be within manufacturing tolerances in every respect apart from its diameter. Several weeks of head scratching interspersed with visits to numerous departments that might be able to throw light on the problem, brought no success. The issue was a complete mystery, and I subsequently wrote my report saying that there was no explanation other than that it had been inexplicably manufactured to that size, for reasons that were a complete mystery. Of course, the moment that the report was published, out came the many other oversize discs that had been carefully hidden from sight, demonstrating that it was not unusual at all, but the usual result of testing items to beyond their elastic limit. What had been unusual about the one I had been given, however, was an astonishingly uniform circularity. All of the other examples were noticeably distorted and heat-stained, lacking the perfection of the one carefully cleaned up and used to put egg on my face. Oh, how we all laughed.

 Apart from occasional glitches such as that, our departmental success had been considerable in the three years I had been there. Machine-Capability tests and changes to the inspection regime had done the trick, and the scrap-rate was falling back to low single-figures. It was inevitable that the massive expansion of the department would eventually be reversed, but I was to uncover one more shocking fact that was to seal my fate....