System Maintenance Manual

Page 2-8 G1000/GFC700 System Maintenance Manual – C90A/C90GT/C90GTi King Air
Revision F 190-00682-01
• standby attitude indicator (operation and internal lighting)
•
standby altimeter (vibrator and internal lighting)
•
standby airspeed indicator (lighting only)
The aircraft power buss provides a trickle charge to the PS-835 under normal conditions. This battery is
existing in the rear fuselage of aircraft previously equipped with Collins EFIS and is installed in the nose
avionics bay by this STC, on aircraft that were not previously equipped with Collins EFIS.
2.1.20 Engine Signal Conditioning
Changes to the engine signal conditioning components were initiated with STC SA01456WI-D Master
Drawing List (MDL) 005-00375-30, Revision 5. The Sandia ST26 Tach Generator Unit (PN 305662-00),
Senior Aerospace PC920 Signal Conditioning Unit (PN PC920-6A00PH-2A1) and the Garmin 005-00375-
93 Tach-Gen Filter Assembly were replaced by the Vibro-Meter (Meggit) Signal Conditioner Signal
Conditioner. Reference the Main Instrument Panel Installation drawing listed in Table 1-2 for the locations
of the Signal Conditioner Components.
2.1.20.1 Sandia Aerospace ST26 Tach Generator Adapter Units (2)
The ST26 Tach Generator Adapter Units are used for converting the signal from the propeller speed and
turbine speed sensors into a signal that is usable by the GEAs. The output signal from this adapter unit will
be represented by a 5 VDC square wave signal at same frequency of input signal. The No. 1 ST26 (left side)
unit is connected to the No. 1 Triple-fed bus and the No. 2 ST26 (right side) unit is connected to the No. 2
triple-fed bus.
The Sandia Aerospace ST26 Tach Generator Adapter Unit is applicable only to installations using STC
SA01456WI-D Master Drawing List (MDL) 005-00375-30, Revision 4 and previously approved revisions.
2.1.20.2 Senior Aerospace PC920 Signal Conditioning Unit
The PC920 unit was installed per this STC only for aircraft with Senior Aerospace Ketema fuel flow
transducer, part number 1/2-2-81-306. The PC920 unit is used for converting the signal from the fuel flow
sensor into a variable 0 to 5 VDC signal that is proportional to flow rate. The PC920 unit No. 1 channel is
connected to the No. 1 triple-fed bus and the No. 2 channel is connected to the No.2 triple-fed bus. The No.
1 channel (connector P9201) converts the fuel flow signal for the left engine and the No. 2 channel
(connector P9202) converts the fuel flow signal for the right engine.
The Senior Aerospace PC920 Signal Conditioner Unit is applicable only to installations using STC
SA01456WI-D Master Drawing List (MDL) 005-00375-30, Revision 4 and previously approved revisions.
2.1.20.3 Garmin 005-00375-93 Tach-Gen Filter Assembly (2)
The Tach-Gen Filter Assembly is used to filter out high frequency signal noise and is installed between the
Sandia ST26 Signal Conditioner and both the propeller speed and turbine speed sensors. There is one tach-
gen filter installed for each engine. The left engine tach-gen filter is installed on the underside of the floor
panel located forward of the pilots seat position. The right engine tach-gen filter is installed on the underside
of the floor panel located forward of the co-pilots seat position. There are no power requirements for the
tach-gen filter assembly.
The Garmin Tach-Gen Filter Assembly, 005-00375-93 is applicable only to installations using STC SA01456WI-D
Master Drawing List (MDL) 005-00375-30, Revision 4 and previously approved revisions.
2.1.20.4 Vibro-Meter (Meggit) Signal Conditioner (2)
Each GEA 71 receives signals from its on-side engine turbine speed sensor, propeller speed sensor and fuel
flow sensors via a Vibro-Meter (Meggit) Signal Conditioner. This unit converts the signals from the engine