Bouy15
The aircraft we are discussing was XW666, you talk with seeming authority, unfortunately, you’re wrong in the detail, and more importantly, wrong in your conclusions.
First the detail. Yes there had been a history over the years of ‘flickering’ lights, but these I believe were Air Start Valve (ASV) indications. It was a short on the engine wiring loom of XW666 which caused an Air Start Valve to open, this was indicated on the flight deck by a warning light. This allowed air to go to the starter motor which ran up under no load. Before it’s design maximum rpm, a retaining nut failed. Now this is the real detail. The retaining nut failed because of hydrogen embrittlement, this failure mode had been identified about 10 to 15 years before, on at least two occasions. A modification programme had been instigated to ensure that all starter motor retaining nuts were replaced. This was nothing to do with flickering ASV lights, it was because starter motors could fail before their design maximum rpm. If they failed, as XW666 showed, the effects could be catastrophic.
Now your conclusions:
why 666 was not modified during it's major is a mystery - it should have been picked up on its pre-major survey
A mystery ? This aircraft had been flying for at least 10 years since the failure mode had been identified, it would have been through at least 2 major cycles. That would be 2 majors, 2 minor stars, 4 minors and 8 primary servicings, minimum, and you talk about pre-major surveys and mystery. I haven’t included engine changes. Following the accident the fleet was checked and others found with similar wiring problems, others too with the pre-mod starter motors fitted. So don’t talk about mystery.
This was a failure of management, it was a failure of the airworthiness and safety management system. In typical fashion, the BOI does not pay proper attention to this.
In my humble opinion, Murphy's Law and Sod's Law creeps into this tragic XV230 incident
Murphy’s Law and Sod’s Law ? what kind of excuses are these ? As so many on here have debated, this situation seems to have been foreseeable. Certainly any reasonably robust safety analysis would have identified the hazards and the risks associated. You’ve even identified some of the failure modes yourself – possible early failure of seals etc due to exposure to excessive ambient temperatures. Yet you still refer to Murphy and Sod.
Please, leave the engineering to engineers !
S_H