A.L.1 PART IV - EMERGENCY HANDLING
Para. 91(a)
contd. (b)(c)
Page 86 when no service is being operated, then hydraulic failure should
be suspected. The red warning light, and the audio warning
when Mod. 327 is fitted, should come on if the pressure falls
below 600 lb./sq. in.
(ii) If the hydraulic supply presuure fails, there may be sufficient
reserves in the power controls accumulators for a maximum of
3½ full reversals of aileron and elevator, the actual reserve
depending on the state of charge of the respective accumulators
at the time of failure. However, even if no control movement is
made, accumulator pressure will not be maintained for a long
period, due to normal hydraulic component seepage. When the
accumulators are exhausted the controls will revert automatically
to Manual.
(iii) A failure in the power controls hydraulic circuit, as distinct from
supply failure, may lead to immediate and automatic Manual
reversion when the prerssure at the locking pawls has fallen well
below that at which the warning light becomes illuminated.
(iv) The wheel brakes accumulators provide sufficient pressure for
brake operation during landing down to an accumulator pressure
reading of 750 lb./sq. in. approximately.
(b) Action in the event of complete hydraulic failure
(i) Complete failure will be indicated by a loss of pressure on the
gauge followed by the red light coming on and by the audio
warning.
(ii) Immediate action should be:-
(1) Reduce speed to 150 knots or, if above 40,000 ft., 0.80M.
(2) Release the aileron trim safety lock and check that the trim
indicator shows zero.
(3) The controls may be left in Power, providing electrical supply
is normal, but when Manual reversion occurs, and in any
case at a safe height before joining the circuit, switch OFF
elevator and aileron Power.
(iii) Lower the undercarriage and flaps on the emergency systems.
(c) Partial hydraulic failure
Partial hydraulic failure can occur due to a type of leak which could
cause complete loss of pressure during the operation of a service, but
which would allow pressure to build again when the operation is
complete. This type of failure can cause the power controls to dis-
engage temporarily and re-engage with the possibility of a false
anchorage.
-----------------------------------------------------------------
(d) Action in the event of partial hydraulic failure
(i) Reduce speed to 250 knots or 0.80M.
(ii) Release aileron trim safety lock and check that trim
indicator shows zero.
(ii) The controls may be left in Power to assist in
manoeuvring, providing electrical supply is normal,
86
|
