Method of starting a gas turbine helicopter engine, a fuel feed circuit for such an engine, and an engine having such a circuit

[0022]In the FIG. 2 fuel feed circuit, there can be seen, as in the circuit of FIG. 1, a pump 30 for taking fuel from a tank (not shown) to be delivered under pressure in a feed pipe 32 having a metering valve 34 mounted therein to control the fuel flow rate.

[0023]A plurality of main injectors 40 are mounted on a wall of a combustion chamber (represented by 42) to inject an air and fuel mixture into the combustion chamber. One 40a of the main injectors 40 is connected directly to the feed pipe 32 via a pipe 35. The other main injectors are connected to the feed pipe 32 via a circuit that comprises in parallel both a rated retaining valve or level valve 36, and an on / off valve 38 mounted in a pipe 39 bypassing the level valve 36, the pipe 35 being connected to the feed pipe 32 upstream from the level valve 36. The level valve 36 imposes a preadjusted head loss, e.g. of 6 bars to 10 bars (0.6 MPa to 1 MPa), e.g. by means of a rating spring. The on / off valve 38 may be electrically con