STUDENT GUIDE T-39N/G NATOPS
d. Over temp.
e. Over time (pump on longer than 1 minute).
f. Over current.
g. Pressure < 2000 + 100 psi. Only time that the master caution light does not come
on with an annunciator light. Will see in connection w/ speedbrake operation.
3. Hydraulic fail audible warning (on deck ONLY)
a. Weight on wheels and either Engine Master ON.
b. Pressure < 2000 + 100 psi (Horn off when > 2600 + 100 psi).
c. Pump switch OFF&RESET.
d. Pump CB out.
C. Aux hydraulic system
1. Pressure 2800-3600 psi (aux accumulator 1500 + 50 nitrogen pre-charge).
2. Powers speedbrake, wheelbrakes/anti-skid and NWS.
3. AUX SYS switch - select ON just before hydraulics are needed if main system fails.
(allows stored pressure fluid to be used from aux accumulator)
4. Hydraulic pressure will bleed down with each actuation of speedbrakes, wheelbrakes,
and nosewheel steering.
5. Recommend turning anti-skid OFF prior to landing. Recommend not using speedbrake.
D. Landing gear
1. Electrically controlled, hydraulically actuated
a. Steady-red light in handle when one or more gear do not correspond to gear handle
b. Flashing red light in handle when gear is not down & locked and the conditions in
paragraph D.5 are met.
2. 180 KIAS & 0 - 2g = operating limits
3. Landing gear override button
a. Allows gear handle to be raised with weight on wheels and hyd./elec. power available.
(Normally, weight on wheels sensing switch prevents gear handle from being raised with
weight on wheels).
b. Can be used on a single eng climb after take-off with a faulty weight on wheels switch.
4. Emergency T-handle allows gear to freefall. Do not roll out over arresting gear because main
gear doors will be open.
4-2 HYDRAULIC SYSTEMS