PART I-DESCRIPTIVE

     (c)  A.C. Supply-post mod. 607

     (i)  When mod. 607 is embodied, separate switches are
          provided for the inverters together with a changeover
          magnetic indicator (38). The magnetic indicator is
          situated on the port instrument panel, the FLIGHT
          INSTRUMENTS EARLY START switch adjacent
          to the starter button on the centre instrument
          panel and the INVERTER RESET switch on the
          starboard shelf aft of the D.M.E. control panel.

    (ii)  Before starting, when the EARLY START switch is
          set ON, No. 2 inverter starts up and supplies A.C.
          The magnetic indicator shows white. When the
          engine is started, auto-changeover to No. 1 inverter
          occurs when engine r.p.m. are at ground idling: the
          magnetic indicator changes to black.

   (iii)  If, during taxying, the magnetic indicator changes to
          white again it shows that auto-change back to No. 2
          inverter has occurred. If this occurs the INVERTER
          RESET switch should be held momentarily to OFF,
          when a black indication should be restored. If the
          indicator remains white, it is an indication that No. 1
          inverter has failed and No. 2 only will he operative.

    (iv)  After take-off, when the nose-wheel door is retracted,
          an override relay ensures an alternative supply
          circuit so that, even if the EARLY START switch
          is inadvertently knocked OFF during flight, contin-
          uity of supply to No. 2 inverter will be available. If
          No. 1 inverter fails in flight, auto-changeover to No.
          2 occurs and the magnetic indicator shows white.

     (v)  A No. 1 INVERTER GROUND TEST switch is
          located in the port side of the nose-wheel hay and is
          for servicing purposes only.

20A