PART 1 - DESCRIPTIVE
of the seat pan. These units allow the cords to pass
freely down through the unit, but prevent them
passing upwards. Thus on ejection the cords are
pulled downwards through the units pulling the legs
close to the seat pan. The legs are held there until
the safety harness is released. The cords are then
pulled through the calf-strap D-rings and free the
legs. A release button is provided under each
snubbing unit to allow the occupant to adjust the
cords to give comfortable leg movement in the
(c) Mk. 3H seat
The Mk. 3H seat incorporates leg restraint cords and
the 80 ft./sec. ejection gun. No thigh guards are fitted. A
Mk. 9 parachute must be used Mod.295 introduces the
seat pan alternative firing handle. The operation of the
seat is as given in (a) (ii)-(vii) and (b)above.
11. Oxygen system
(a) Oxygen is carried in two Mk.5D cylinders. A Mk. 17
demand regulator (71) controls the supply to the pilot.
Later aircraft may be fitted with a Mk. 18 regulator.
(b) A contents guage (72) is mounted on the right of the
instrument panel. The regulator consists of an on/off
valve which controls the flow of oxygen, an air inlet
NORMAL-100% OXYGEN switch, an emergency three-
position switch and a combined flow and blinker unit.
(c) When the on/off valve is on and the inlet switch is at
NORMAL an air/oxygen mixture is fed to the pilot's
mask, up to a height at which 100% oxygen is automatic-
ally delivered. When the inlet switch is at 100%
OXYGEN, no air is added, irrespective of the height.
This position should be selected if any symptoms of
anoxia are present. The emergency switch when moved
to either right or left admits oxygen under greater
pressure. Normally it should be central but should be
offset if cabin pressure failure occurs.
(d) The mask maybe tested before flight by firmly pressing
in the emergency switch, when in the central position