A.L.1 PART IV - EMERGENCY HANDLING
Page 85
(iii) Provided that the engine is running correctly and hydraulic
pressure is normal the flying controls may be left in Power. The
magnetic indicators will show white when the batteries are dis-
charged although the controls will remain in Power.
NOTE.-1. If any doubt as to the serviceability of the hydraulic
system exists, select Power OFF before the batteries are
discharged, unless Mod. 502 is incorporated.
2. If it is necessary to descend more rapidly than at normal
gliding speed, 15° flap may be used to increase the rate
of descent, but speed must not exceed 0.9M and the
tailplane incidence must be left at ½° nose-up. Interme-
diate degrees of flap can only be selected while electric
power is available. The pull force needed to reduce speed
to 210 knots will be considerable if in Manual.
(e) Emergency operation of the tailplane and electrical follow-up tail
malfunction
(i) If the normal tailplane motor fails or "runs away", lift the
cover of the standby switch on the port shelf and use that con-
trol. Rate of operation of the latter is about one-third that of
the normal control. If complete electrical failure occurs, control
of the tailplane is impossible. It is important therefore to set the
tailplane to ½° nose-up before the batteries are fully discharged.
(ii) If the follow-up tail malfunctions, either in its capacity as a
flying control or in its trimming action, the standby trim switch
cover must be lifted immediately. The standby actuator can
then be used to obtain satisfactory trim. It is possible that the
malfunction may not affect the main trim actuator with TAIL-
PLANE selected OFF although it might have shown itself
during either normal control movement or trimming with
TAILPLANE ON. After raising the standby trim switch cover,
select TAILPLANE OFF, then reselect the main actuator and
check the normal trimming action. If the malfunction is still
present, revert to the standby actuator and return to base.
(f) Aileron trim malfunction in Manual
(i) When flying in Manual should the aileron trim actuator mal-
function resulting in full trim being applied with subsequent
inability to rectify carry out the following actions:-
Reduce speed below 200 knots.
Select elevator power ON.
If above 5,000 ft. select aileron power ON; if below 5,000 ft.
leave ailerons in Manual (but see (iii) below).
Land as soon as possible.
(ii) If a one-way restriction occurs when reselecting aileron power
clear it in the normal way. If a both-ways restriction occurs
reselect Manual immediately and remain in Manual.
(iii) A landing in Manual with full aileron trim applied will be
hazardous and should only be attempted if conditions are
favourable.
91. Hydraulic system failures
(a) Complete hydraulic failure
(i) Periodic checks of the triple pressure gauge should be made in
flight and the central needle should normally read 2,850±150
lb./sq. in. If the reading drops substantially below this figure
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