Gulfstream G550, Operating Manual

Page: 73 / 94

(5) Both main landing gear weight on wheels (WOW) switches in the
ground position OR both main landing gear wheel speeds (sensed
by the anti-skid sensors) greater than forty-seven knots (>47 kts)
OR one main landing gear WOW switch in the ground position and
the other main landing gear wheel speed greater than forty-seven
knots (>47 kts).
NOTE:
The relationship between the WOW switches and
wheel speed is necessary to accommodate the wide
range of conditions encountered during landing. An
extremely gentle touchdown would spin up the wheels
but not immediately compress the WOW switches. A
very firm landing may compress the WOW switches
but not immediately spin up the wheels. Strong
crosswinds may result in one WOW (upwind) switch
being compressed and the opposite wheel (downwind)
spinning
up prior to the WOW switch being
compressed.
CAUTION
A HARD LANDING THAT RESULTS IN A
SIGNIFICANT BOUNCE WILL DEPLOY THE
GROUND SPOILERS IF THE POWER LEVERS ARE
MAINTAINED AT IDLE, RESULTING IN A RAPID
LOSS OF LIFT AND AIRSPEED DURING THE
SUBSEQUENT TOUCHDOWN. ADVANCING THE
POWER LEVERS WILL RETRACT THE GROUND
SPOILERS AND DECREASE THE SINK RATE IF THE
AMOUNT OF RUNWAY REMAINING ALLOWS SAFE
COMPLETION OF THE LANDING.
For automatic ground spoiler deployment in conditions that require landing
with less than full (39°) flaps, the following logic parameters are necessary
for abnormal landing operations:
(6) The SPOILER CONTROL pushbutton selected ON.
(7) The GND SPLR pushbutton selected to ARM.
(8) Wing flaps selected to less than twenty-two degrees (22°).
(9) The GPWS / GND SPLR FLAP ORIDE pushbutton on the center
console forward of the flap handle selected to ON (amber ON
legend in the pushbutton illuminated) - see Figure 21.
(10) Both power levers retarded to idle.
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS
2A-27-00
Page 73
August 14/03
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