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  • #16
    No, because you know that some components will fail and you will even have a rough idea of how reliable they are.
    If the same transistor failed more than once, then you would start looking into what (if any) is the underlying cause.
    If a power supply failed, it would be replaced and, if it failed again, someone would be looking to see what caused the failures.
    With batteries, I have never experienced catastrophic failures that were not caused by external action such as someone connecting it up wrong, dropping their spanner on it etc.
    There are batteries driving radio sites in the Middle East that I installed nearly 20 years ago. None have ever decided to burst into flames.
    On the other hand, a new transmitter/receiver was being introduced on a massive scale by my former employers and they kept failing. One day, a meeting was held to discuss the fix the development people had found and we (about 15 people in UK & US) were asked to agree to support the fix. I refused on the grounds that it was my team that would be lumbered with constant calls from irate customers and short notice trips to Holland, South Korea and the Middle East. When the development people admitted they seemed to have stumbled on something that seems to stop the fault, yet they did not know the cause of the fault, they had to go away and do the job properly. A month later, they had found the 'real' fault and re-designed their fix. Some of the development team later told me they were glad I had stopped the roll out of this fix and forced them to find the root cause. Saved the company millions in support costs and penalties.


    • #17
      Boeing really aren't having a good day just found out LAN 787 was diverted after overheating was detected


      • #18
        A Thomson Airways Boeing 787-800, registration G-TUIC performing flight BY-126 from Manchester,EN (UK) to Orlando Sanford,FL (USA), was enroute at FL390 about 400nm west of Shannon (Ireland) when the crew decided to turn around and return to Manchester maintaining FL390 on the return. The aircraft entered a hold over the Irish Sea for about 3 hours to burn off fuel and landed safely back on Manchester's runway 23R about 5.5 hours after departure.

        The airline said the aircraft returned as a precaution after suffering a technical problem. The passengers have disembarked and are going to board another aircraft.

        Passengers reported that all but 2 lavatories malfunctioned obviously as result of an electrical problem.



        • #19

          Very good approach. I did the same thing in the past. One heavy duty Power supply HP6000 series - 48 V DC 50 Amps - Triac always failed when operating in countries with 230 V 50 Hz.

          HP never do anything about it - they told me it never failed in the USA ( 60 Hz ).

          I did fault analysis - found the power transformer the Triac was driving - designed for 60 Hz Operation. When it operated on 50 Hz, the effective Impedance was lower and it heated up so bad you can toast a piece of bread on it.

          Eventually, the customer dump ALL their HP 6000 Series Power Supply and bought Farnell ( designed to operate om 50 Hz ).
          F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.


          • #20
            Along the same theme; is it possible that the 787 has deeper rooted electrical issues?
            There is a suspicion that the Thomson flight had electrical issues.
            There is gossip trying to point a finger in the Ethiopian case at an overheating coffee machine. I very much doubt that; as the the aircraft had been on the ground, everything switched off and cold for something like 11 hours. If the coffee maker had been the cause, surely it would have been apparent much sooner than 11 hours later.
            Unless something had applied "uncommanded" power to the machine. See the ANA battery problem report where it was found that the difference in voltage between the APU and main batteries caused the strobe and wing tip lights to come on "uncommanded"; ie. they were not switched on.
            Added to all this is the failure of a United 787 at Heathrow on Tuesday. Their flight to Houston was cancelled because of issues with a "message indicator" (United's description.). Unless it was a mechanical semaphore system, I assume this will be an electrical failure too. The same aircraft, on the same route, had to make a diversion to Newark on June 20th due to "low engine oil indicator".
            Something that puzzles me is the range of voltages used on the aircraft (I suppose other aircraft may be the same?).
            The 787 has 235VAC (anywhere between 360Hz & 800Hz), 115VAC (presumably 60Hz), 28VDC and 270 VDC. Why? Why not choose a voltage/frequency and specify all equipment will work at these voltages/frequencies?