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FEATHER
LEGEND
NO. 1 GENERATOR
NO. 2 GENERATOR
BATTERY
PROPELLER
SYNCHROPHASER SYSTEM
A Type II synchrophaser system is installed
in the King Air C90GTi and C90GTx. The
p r o p e l l e r s y n c h r o p h a s e r a u t o m a t i c a l ly
matches the r pm of the two propellers and
maintains the blades of one propeller at a
predeter mined relative position with the
blades of the other propeller. The pur pose
of the system is to reduce propeller beat and
cabin noise from unsynchronized propellers.
Synchrophaser Operation
The Type II synchrophaser system (Figure 7-
40) is an electronic system, certif icated for
takeoff and landing. It is not a master-slave
system, and it functions to match the rpm of
7-42
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
POWER LEVER
SWITCHES
LEFT
ARM
C/B
OFF
AUTO–
TEST
RIGHT
CLOSED AT
HIGH N 1
Figure 7-39. Autofeather Test Diagram
FOR TRAINING PURPOSES ONLY
TORQUE SWITCHES
LESS THAN
400
FT LBS
ARMING
RELAY
AUTOFEATHER
OVER
ARMING
400
RELAY
FT LBS
both propellers and establish a blade phase
relationship between the left and right pro-
pellers to reduce cabin noise to a minimum.
The system cannot reduce rpm of either pro-
peller below the datum selected by the pro-
peller control lever. Therefore, there is no
indicating annunciator light associated with
the Type II system.
To prevent either propeller from losing ex-
cessive r pm if the other propeller is feath-
e r e d wh i l e t h e s y n c h r o p h a s e r i s o n , t h e
synchrophaser has a limited range of au-
thority from the manual governor setting.
In no case will the r pm fall below that se-
lected by the propeller control lever. Normal
gover nor operation is unchanged, but the
synchrophaser will continuously monitor
LESS THAN
200
FT LBS
N.C.
DUMP
VALVE
LIGHTS
N.C.
DUMP
VALVE
OVER
200
FT LBS
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Do you have a question about the C90GTi and is the answer not in the manual?
Questions and answers
When both genties open with both generators on line and you manually close them, would you see MAN CLOSE green annunciation light?
No, the MAN TIES CLOSE annunciator activates only when the generator bus tie relays are manually closed using the switch. If both generators are online and operating normally, the bus ties close automatically, and the MAN TIES CLOSE annunciator does not activate.
This answer is automatically generated
King Air 350 abnormal checklist: Both Gen Ties Open. You Manually close the Gen Ties with both Generators on line. Why, the next step in the checklist says: MAN TIES CLOSE-ILLUMINATED? They shouldn’t be since both generators are on line.
The "MAN TIES CLOSE" annunciator illuminates when the generator bus tie relays are manually closed, completing a latching circuit. This prevents the automatic closing of the bus ties and activates the annunciator readouts. Even if both generators are online, the manual closure of the Gen Ties switch forces the relays to stay closed, triggering the indication.
This answer is automatically generated
Thank you so much! Joe
Abnormal checklist BOTH GEN TIES OPEN. You manually close them. Next step in checklist: MAN TIES ILLUMINATED. They shouldn’t be since generators are on line. Does that mean ANY time you manually close them regardless of generator status, the MAN CLOSED light illuminates?