34 mode in which the main stage 14 operates in lieu of starting stage 18 and a switching piston 36 which upon receiving the appropriate signal from the brmtv 32 strokes to either activate or deactivate the regenerative starting stage 18 by opening or closing off the starting stage flow channel 38 see fig2 an integral part of the present invention is brmtv 32 its structure is best depicted in fig6 as shown therein this valve comprises a chamber 39 with an 34 upper 34 sleeve 40 held in position by a cover 42 an main valve body 44 that slides relative to sleeve 40 and cover 42 within the chamber 39 to selectively open or close a start stage window 46 or a bypass window 48 a spring 50 that rests against shims 52 inside the cover to bias the main body 44 toward its position shown in fig1 and various o rings 54 56 58 60 to provide liquid tight seals fig7 best illustrates the check valve 34 like brmtv 32 this valve includes a main body 62 that slides inside a sleeve 64 and chamber 66 the sleeve is held in fixed position by a cover 68 and a spring 70 inside the cover tends to bias the valve to its closed position shown in fig2 various o rings 72 74 76 provide liquid tight seals the check valve 34 is connected to a reference line with a pair of screens and a damper hole at 78 the damper provides dynamic stability for similar stability there are a pair of screens and a damper hole at 80 associated with the brmtv 32 during operation of the aircraft.