Re: A 777 with four engines.

Date:         06 Aug 98 23:22:46 
From:         Pete Mellor <pm@csr.city.ac.uk>
References:   1
Followups:    1
Next article
View raw article
  or MIME structure

On 6 Aug 1998, jchase wrote:
> Is there any record of a double engine failure and subsequent aircraft
> loss on a twin-jet from separate causes? - that is, exclude volcano dust
> or bird ingestions killing both engines, running out of fuel, or other
> events that kill ALL engines regardless of number.

While we are on the topic of multiple engine failures (regardless
of which engine failed first! :-) I would like to raise again a
thorny old topic, i.e., to what extent might the fact that the
engines are controlled by the same FADEC render the A/C prone to
multiple engine failure due to the activation of a latent design
fault in the FADEC?

I have tried to get information on the FADEC on several occasions,
but without too much success. In particular:-

- Who manufactures FADECs? (I know that they come as an integral
  part of the engine, and hence are the responsibility of the engine
  manufacturer, but I presume the engine manufacturers outsource
  FADEC development? If so, to whom?)

- I believe that the FADEC is a dual-channel device, but with
  identical software in both channels. Hence it has a certain
  amount of hardware redundancy, but no design diversity, between
  the channels.

- Are the FADECs used in helicopters in any way similar to those
  used on turbofans? (Same manufacturer? Same hardware? Different
  software?)

I know that the FADEC as a potential source of common-cause failure
is of concern to the certification authorities. (An interesting AD
on the subject was issued several years ago.)

Any information on FADECs would be very welcome.

Pete Mellor, CSR, City University, London

PS: Were those birds participating in the strike independently,
or deliberately flying in close formation? :-)