L-1011 Trainer Installation: AFCS Mode and AFCS Warning Panel Power Up

L-1011 AFCS Mode Annunciator - FO Side

Had to hold off on working on more instrument lighting today due to the fact that we ran out of the type terminal block we use for the different light buses. No need to mix and match and hopefully over the next week or two we will have a fresh supply of terminal blocks.

So, switched to the AFCS Mode and AFCS Warning Annunciators today. I have actually quite extensively blogged about these two instruments; check out:

Pinout and Demo of the AFCS Warning Panel

and 

AFCS Mode Annunciator Breakdown

The four annunciators (two on the Captain's side and two on the FO side) are now powered up and can be self tested. The AFCS Mode annunciators have breakers on the CB1 panel and the AFCS Warning annunciators have their breakers on the CB2 panel.

L-1011 AFCS Warning Annunciator - Captain's Side

L-1011 Trainer: AFCS Mode and Warning Indicator Location

L-1011 AFCS Mode Annunciator - Captain's Side

Avionics Bending: AFCS Modes (Pinout)

Finished connecting the AFCS Modes displays to the relay boards. The AFCS MODES display is used to display the autopilot modes and to indicate state changes. For example from ALT ARM to ALT ... which indicates a change in autopilot state from altitude arm to altitude capture. I have a more detailed description of this instrument in several other blog postings such as: AFCS Training Manual Description, AFCS Modes Instrument Analysis and Localizer Capture Example. Here is what the instrument looks like:

And here is a short video of the instrument powered up and connected to the relay board backend. The instrument requires a power source between 24VDC and 28VDC and a 5VDC power source for instrument lighting. The individual flag solenoids are operated by pulling the respective pin to Ground.

The pinout below is for a an AFCS Modes panel used on an L-1011 with Thrust Management (TM). On AFCS Modes panels for L-1011s without TM, the THR MGT flag will simply say "TEST".

Pin	#	Pin Assignment	Value
A	32	Unused
B	31	Power	28VDC
C	30	A/L (W)	GND
D	29	A/L ARM (B)	GND
E	28	LOC (W)	GND
F	27	LOC ARM (B)	GND
G	26	GS (W)	GND
H	25	GS ARM (B)	GND
J	24	ALIGN (W)	GND
K	23	Instrument / Test Switch Ground	GND
L	22	ALIGN ARM (B)	GND
M	21	FLR ARM (B)	GND
N	20	VOR (W)	GND
P	19	THR MGT (W)	GND
R	18	Unused
S	17	Unused
T	16	Unused
U	15	Instrument Light
V	14	Instrument Light	GND
W	13	HDG SEL (W)	GND
X	12	TURB (W)	GND
Y	11	VS (W)	GND
Z	10	ALT (W)	GND
a	9	TO/GA (W)	GND
b	8	FLARE (W)	GND
c	7	ROLLOUT (W)	GND
d	6	VOR ARM (B)	GND
e	5	L NAV (W)	GND
f	4	ALT ARM (B)	GND
g	3	WINDSHR (W)	GND
h	2	IAS (W)	GND
j	1	VNAV (W)	GND

L-1011 Autoflight: Go-Around Mode (22-44)

When the GO-AROUND button is pressed, the autopilot will roll "wings level" and pitch the airplane to maintain 1.25Vs minimum speed or 17.5º maximum pitch attitude whichever produces the higher airspeed. The speed command system automatically provides these computations for autopilot use. The direct lift control (DLC) function is disabled andy he YAW SAS system remains in a parallel mode of operation in which rudder pedal movements may be felt.

Verification of GO-AROUND mode selection is made by checking for GO ARND message on both AFCS MODES annunciators.

If the flight directors were on at the initiation of GO AROUND, they should be left on until a positive rate of climb is achieved or a 17.5º pitch attitude is reached.

L-1011 Autoflight: Takeoff Mode (22-43)

The TAKEOFF mode provides pitch and roll guidance. Roll guidance is wings-level only, with no heading reference. Pitch guidance commands a pitch attitude that will produce an angle of attack that corresponds to an airspeed of 1.25Vs for the existing flap setting, up to the established takeoff pitch attitude limit. Excess thrust that would otherwise cause this limit to be exceeded is converted into airspeed acceleration.

Remember, takeoff can be selected at any time while on the ground. Verification of mode engagement is made by observing the TAKEOFF message on both AFCS MODES annunciators.

L-1011 Autoflight: Verification of Command Mode Engagement (22-12)

Each time a command mode is selected, both autopilot computers will respond by displaying the selected mode on the respective AFCS MODES annunciator. Each autopilot computer has an AFCS MODES annunciator located on the main instrument panel. In the example above, autopilot A is in the command position and vertical speed has been selected as a pitch command mode. The "VS" light on the Pitch Panel indicates mode selection, verification of both autopilot computers operating in the "VS" pitch mode is accomplished by observing the "VS" message in both AFCS MODES annunciators.

"VS" is also displayed int he PITCH Panel window (digital autopilot system only) along with the actual vertical with the actual vertical speed at the time of engagement.

L-1011 Autoflight: AFCS Mode Annunciators (22-11)

Verification of mode engagement is accomplished by observing the message on both AFCS MODES annunciators. An AFCS MODES annunciator is located on the top of each pilot's instrument panel.

L-1011 Autoflight: Command Modes (22-10)

Once an autopilot lever has been placed in CMD or or command, it continues to act as if it were in control wheel steering until pitch or roll command modes are engaged.

Command modes are selected by pressing the switchlights along the top of the autopilot panels. Only one pitch mode and one roll mode can be selected at a time. Selection of a second pitch or roll mode will automatically disengage the first pitch or roll mode. Selection of a command mode will cause both autopilot computers to operate in that mode even though only one computer is engaged.

The switchlight for each mode will illuminate to show positive mode selection.

Avionics Bending: AFCS Mode Indicator (Analysis)

Many people described the Lockheed L-1011 as the electronically most advanced aircraft of its time. I would agree with that. One of the center pieces of the L-1011 is its flight control system. the posting today shows the AFCS Mode instrument that is used to display the control mode that the avionic flight control system is in. I will give a little bit of an overview of each mode towards the end of this posting.



This particular type of mode indicator was also used in other aircraft, but this one was build specifically for the Lockheed L-1011 by Collins Avionics. Compared to other instruments, the casing is held in place by a massive amount of screws. There are a total of 10 of them.


On the inside, the instrument is rather basic. There are a number of solenoids that work in tandem to show 3 sides of each mode annunciator (typically one side is blank or just black). The solenoids stick out because they look like silver tubes or rods.

Top View

Right hand side view

Bottom view

Left hand side view


The annunciator has two test buttons on the top left and top right of the instrument. The TEST-1 button flips all indicator fields down and the TEST-2 button does the opposite. This would be used to test the functionality of the indicator prior to flight or during flight.



The next two pictures show the action of each of the two TEST buttons when they are depressed.




There are two general differences in the modes. The modes are either black letters on a white background or white letters on a black background. The two have different meaning:

1. White Letters on Black Background - is a mode that is ARMED but has not engaged yet. For example, ALTITUDE (ALT) capture can be ARMED (ALT ARM) until the aircraft reaches the selected altitude. Hence, first we would see a ALT ARM flag first and then an ALT flag.
2. Black Letters on a White Background - indicates an active mode or warning (e.g. Windshear).