User Guide

223
Flight Instruction
222
Flight Instruction
STARTUP
A gas turbine is particularly vul-
nerable to damage during startup,
when there’s a risk of getting a big, hot
fuel fire going before there’s enough
airflow through the engine to handle
its internal cooling needs. When you
crank up a piston engine, you can let
go of the starter button or key as soon
as the engine fires. A turbine, on the
other hand, needs the help of the
starter to accelerate all the way up to idle speed (a much larger
fraction of normal operating speed than with a piston engine). If
you quit cranking too soon, you’re likely to experience what’s
called a “hot start,” in which the turbine exceeds its ITT limita-
tions. Pratt & Whitney cut you a little slack here: while maximum
ITT is 800 deg. C for takeoff and 770 for high cruise, you’re
allowed to go up to 1000 deg. C during startup - for all of five sec-
onds! In the real world, however, you can consider that there are
no numbers on the ITT gauge beyond 850 - from there out, it’s
nothing but dollar signs!
I suggest that you go over the starting sequence, step by step,
and get it firmly in mind before we actually try it. Once things start
happening, even on a normal start, there’s no time to look at a
checklist - and, without trying to scare you, I should warn you that
a badly botched start could cause up to $100,000 in engine dam-
age in just a few seconds.
Check that the power levers are at idle, the prop controls
fully forward, and the condition levers fully aft, in the cutoff posi-
tion. If you wish, you can check operation of the standby fuel
pumps before turning on the battery master switch by turning each
of them on momentarily and listening for operation. Now turn the
battery switch on and check that the L and R FUEL PRESS annun-
ciators are off; then turn the standby pumps OFF and check that
the L and R FUEL PRESS annunciators illuminate. Briefly press the
MASTER WARN and MASTER CAUTION flashers to reset them.
Before initiating a start, it’s a good idea to press the volt-
meter button on either of the ammeters above the windshield and
verify that you see at least 24 volts. If not, you’re just about guar-
anteed to get a hot start; call for an external power unit.
Behind this, the pedestal accommodates the autopilot/flight
director controller, the cabin altitude selector and pressurization con-
troller, and a short row of switches controlling pressure dumping,
power to the elevator trim system, a rudder boost function that we’ll
explain shortly, and the yaw damper unless it’s part of the autopilot.
Most recent Super King Airs have enough optional equip-
ment (long range navigation systems, remote course arrow and
heading bug selectors, etc.) to warrant making this section of the
pedestal “double width” to accommodate two rows of standard-
size accessories.
LABOR-SAVING DEVICES
Remember that I said that this airplane is easier to fly than a
piston-powered twin? That’s partly because it has several features
that take care of some tasks for you in critical situations.
One of these is “auto-feather.” When it’s armed (normally
only for takeoffs and landings), it monitors the torquemeters of
both engines. If either engine loses power, the auto-feather will
automatically feather that propeller, at the same time disarming
itself on the other side of the airplane to avoid the risk of feather-
ing both engines. Thus, if you lose an engine on takeoff, while you
should still have the old “Identify, Verify, Feather” litany in mind,
you’re more likely to see an initial hard swerve toward the failed
side followed by a reduction in pedal pressure as that engine
feathers automatically.
Another system, working in parallel with auto-feather, is rud-
der boost. A certain amount of air is bled from the compressor of
each engine, primarily for pressurization and environmental pur-
poses. Some of this bleed air is directed to a pair of pneumatic ser-
vos attached to the rudder. If the system detects a large discrepan-
cy in bleed air pressure, as would occur during an engine failure,
pressure from the operating engine is directed to the appropriate
servo to assist the pilot in maintaining rudder pressure on the oper-
ating-engine side.
Finally, there’s auto-ignition. Remember, once “the fire is lit”
in a turbine, there’s no further need for ignition. However, it’s pos-
sible for the fire to blow out, for example if an engine ingests a big
slug of water when the airplane rips through a deep puddle on
takeoff. If either engine drops below 400 ft/lbs of torque, the auto-
ignition system will actuate the igniters on that side to help prevent
a flameout.