Sunday, September 25, 2011

Avionics Bending: AFCS Warning (Pinout)

The AFCS Warning panel is similar to the AFCS Modes panel in the way that it also uses flags to indicate autopilot fault states. In addition to the flags, the AFCS modes panel has an ALERT switch that has to be pressed by the pilots in order to clear and acknowledge the alert flag. The instrument is typically powered from the 28V DC bus on the aircraft but works perfectly find from a 24V DC source.


There are two TEST switches that actuate the flags and the ALERT switch electronics. The ALERT switch itself is used to both clear the blinking ALERT warning and to also clear the fault flag. Watch the short video below if you are interested to see the AFCS Warning panel in action.


The individual flags can be actuated by pulling the associated pin to Ground. Below is the pinout for the AFCS Warning panel as used on the L-1011. 


Pin
#
Pin Assignment
Value
A
41
Power
28VDC
B
40


C
39
Instrument Test Switch
GND
D
38


E
37
NO DUAL (A) - no clear
GND
F
36
AP LIMIT (R) - reset enable
GND
G
35


H
34
NO ALIGN (A) - reset enable
GND
J
33


K
32
NO FLARE (A) - reset enable
GND
L
31
NO FLARE (A) - reset enable
GND
M
30
CMD DISC (A) - can be cleared
GND
N
29
CMD DISC (A) - can be cleared
GND
P
28


R
27


S
26


T
25


U
24


V
23


W
22
Instrument Lighting 
GND
X
21
Instrument Lighting 
5VDC
Y
20


Z
19


a
18
NO DUAL (A) - no clear
GND
b
17


c
16


d
15


e
14


f
13


g
12


h
11
ATS DISC (R) - can be cleared
GND
i
10


j
9


k
8


m
7


n
6
AP DISC (R) - has to trigger together with 1
GND
p
5
NO GA (A) - can be cleared
GND
q
4


r
3


s
2


t
1
AP DISC (R) - has to trigger together with 6
GND

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