I could be wrong


Michael Winning

Didn’t the blasted MOD, onordering Boeing Chinnooks, demand that all the working US software be changed to MOD-ordered stuff?

Isn’t that why we don’t have any of the buggers in Afghanistan? Because they take so long to prepare now?

5 comments

  • The Chinooks operated by the Americans don’t seem to have this FADEC problem. If it ain’t broke, don’t fix it would seem to be the order of the day.

    Tony

  • Median-voting multi-channel FADECS would seem to be the optimum choice.

    FADEC Advantages

    * Better fuel efficiency
    * Automatic engine protection against out-of-tolerance operations
    * Safer as the multiple channel FADEC computer provides redundancy in case of failure
    * Care-free engine handling, with guaranteed thrust settings
    * Ability to use single engine type for wide thrust requirements by just reprogramming the FADECs
    * Provides semi-automatic engine starting
    * Better systems integration with engine and aircraft systems
    * Can provide engine long-term health monitoring and diagnostics
    * Number of external and internal parameters used in the control processes increases by one order of magnitude
    * Reduces the number of parameters to be monitored by flight crews
    * Due to the high number of parameters monitored, the FADEC makes possible “Fault Tolerant Systems” (where a system can operate within required reliability and safety limitation with certain fault configurations)
    * Can support automatic aircraft and engine emergency responses (e.g. in case of aircraft stall, engines increase thrust automatically).

    [edit] Disadvantages

    * True full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer. If a total FADEC failure occurs, the engine fails. In the event of a total FADEC failure, pilots have no way of manually controlling the engines for a restart, or to otherwise control the engine. As with any single point of failure, the risk can be mitigated with redundant FADECs.
    * High system complexity compared to hydromechanical, analogue or manual control systems
    * High system development and validation effort due to the complexity

    [edit] Requirements

    * Engineering processes must be used to design, manufacture, install and maintain the sensors which measure and report flight and engine parameters to the control system itself.
    * Software engineering processes must be used in the design, implementation and testing of the software used in these safety-critical control systems. This requirement led to the development and use of specialized software such as SCADE.

    =============================

    Tony

  • For the same sort of reason that the MoD came up with the SA-80 and foisted it upon the luckless army. It was a disaster. The MoD had to pay Heckler & Koch 140 miliion to redesign and retool it. It was intended to replace the SLR which seems a preferable main battle rifle.

    Tony

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