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LRCNew EquipmentNew Equipment
CN-1716/A Fiber Optic Gyro System
(FOGS)Attitude Heading Reference Unit
(AHRU)
LRCNew EquipmentNew Equipment
CN-1716 (FOG) will replace the three existing gyros
ASN-43(Direction Gyro)
CN-1314 (Vertical Gyro)
and TRU-2A/A (Rate Gyro)
LRCWhat is AHRU?What is AHRU?
• The Fiber Optic Gyro System (FOGS) is a self-contained strap-down Attitude Heading Reference System (AHRS) that provides accurate aircraft pitch, roll, magnetic heading, and turn rate information for integration within an avionics subsystem.
LRC
How FOGS WorkHow FOGS Work
Fiber Optics for Axial Reference replacing the mechanical gimbaled gyros.
Accelerometers electromechanically compensate & stabilize in
flight
AHRU is a self latitude look up system.
Flux Valve provides initial reference in heading
- Post CCAL, flux valve provides updates FOGS filter fluctuations of flux valve which
smoothes out the pitch, roll, and heading output.
LRC
“FOGS”
AHRU CN-1716/UH-60 Gyros Replacement “FOGS”
AHRU CN-1716/UH-60 Gyros Replacement
New Digital Control Improved display and control capability
Improved maintenance and diagnostics functions
Spec Mean Time Between Failure: 6000 hrs. Manufacturer Predicted MTBF: 15,000 hrs)
Significant Simplification of Compass Alignment (you don’t do anything!)
Improved Navigational Accuracy
LRC
InterconnectionsInterconnections
•FLUX VALVE •NAVIGATION SET, AN/ASN-
128•HSI•VSI•AFCS
LRC
AHRU and ASN-128AHRU and ASN-128
• AHRU is not a navigator.
• Supplies information to Doppler in the absence of GPS.
• Improves accuracy of ASN 128
LRCBeforeBefore
LRCAfterAfter
CN 1716
CN 1716
LRC
AHRU
AKA: FOG, SUE, MDU, Lisa....OUTPUTS
•Digital Arinc-429, RS-422: (Heading, Pitch, Roll, Body Rates & Accelerations, Vertical Velocity)
•Synchro Arinc-407: (Heading, Pitch, Roll)
•Analog: (Yaw Rate, Validities, 2 Wires Attitude, Interlock for Autopilot) ACCURACY
•Heading: 0.8 deg. Attitude: 0.5 deg
AHRU (FOGS)AHRU (FOGS)AHRU (FOGS)
LRC
SENSOR ELECTRONIC UNIT (SEU) GENERAL VIEW
SENSOR ELECTRONIC UNIT (SEU) GENERAL VIEW
LRC
“SEU” aka “FOG”AHRU CN-1716/A
“SEU” aka “FOG”AHRU CN-1716/A
23
087-
027
LRCBeforeBefore
Compass Controller
LRCAfterAfter
LRC
DIGITAL CONTROL PANEL (DCP)
DIGITAL CONTROL PANEL (DCP)
LRC
Digital Control Panel
Digital Control Panel
DisplayWindow
SLAVED MODEIndicator
DG MODEIndicator
CCAL MODEIndicator
Alignment ModeIndicator Failure
Indicator
MODESelector
FunctionSelector Display Cursor
MovementEnter Selection
Button
CCAL = Compass Calibration
LRC
AC Power AppliedAC Power Applied
Initial power on: All lamps illuminate for 2.5 seconds.!! LOWER CONSOLE lights have to be ON !!
- DCP performs a lamp self-test / system MOC.
LRCNO DISPLAY?NO DISPLAY?
Turn Lower Console lighting rheostat on to
illuminate DCP.
LRC
• Initial power on: DCP is performing lamp self-test for 2.5 seconds, THEN:
• ALN lamp will be on• ATT fail flag on the VSI will be in view• AHRU will align and self-test within 45 seconds
AC Power AppliedAC Power Applied
LRC
After 45 seconds:• the SYSTEM will automatically default to
the SLAVE mode• and the VSI ATT warning flag disappears
AC Power AppliedAC Power Applied
LRC
BIT STATUS:FOG FAIL !BIT STATUS:FOG FAIL !BIT STATUS:FOG FAIL !BIT STATUS:FOG FAIL !
If the FAIL lamp appears –The Display Window will show two BIT words:
a. LRU/SRU information and b. the failure code.(Write up “AHRU Failed x amount of times”. It is not necessary to write up the failure BIT info/code.)
The CDU stores the last 16 faults.
LRCStarting ProcedureStarting Procedure
Step 1. Mode Selector – As desired. (you always desire SLAVE while you are at FT Rucker)
a. The Lower Console lights have to be on for the lights on the DCP to be seen.
b. The default mode is SLAVE – Therefore, you should not have to move, touch or otherwise fondle anything for it to be in the SLAVE mode.
LRCStarting ProcedureStarting Procedure
Step 1. Mode Selector – As desired. (Continued)
Do Not select anything other than SLAVE!
Do Not select DG unless you are above 70° Latitude (Be sure you have CAO approval to be out of the LFA)
THOU SHALL NOT select CCAL!!
LRCStarting ProcedureStarting Procedure
Step 2. HSI – Check to see that HSI heading agrees with a known magnetic heading (STANBY COMPASS).
If the HSI does not line up after the 45 second alignment time + your patience -
Call Maintenance
LRCFailuresFailures
If a failure is detected, the FAIL lamp will illuminate, and the display window will show a message indicating which AHRU has failed.
Press Enter to clear the fail light
If the fail light clears – continue mission
If fail light does NOT clear – Call maintenance
LRC
ELECTRICAL POWER CHARACTERISTICS
ELECTRICAL POWER CHARACTERISTICS
• A Primary power interruption of less than 200 milliseconds does not cause a system realignment.
• Power interruptions more than 200 Milliseconds CAUSE SYSTEM IN-AIR RE-ALIGNMENT
• The ATT and NAV warning flags will be in view to indicate the system is doing a re-alignment.
• DURING THE RE-ALIGNMENT PHASE, MAINTAIN STRAIGHT and LEVEL UNACCELERATED FLIGHT
(2.5 to 45 seconds)
LRC
““Hold the Hold the Controls”Controls”““Hold the Hold the Controls”Controls”
NOTE During aircraft shutdown,• when engine power control levers are
moved from the Fly to Idle position, or • when the generator switch position is
changed to off, and • electrical power assignment is changed
from Main Generator to APU Generator,• an un-commanded right or left
pedal drive of up to ¼ inch may occur, returning to neutral position within 3 seconds.
LRC
CLTV NULL = YAW DRIFTCLTV NULL = YAW DRIFT
If the Collective Position Sensors are out of null
the aircraft will have a
greater tendency to yaw at hover
than with the older system.
LRCYAW DRIFTYAW DRIFT
Write it upespecially if you have seen fail light
LRC
GYRO ERECT IN SLAVE MODE
GYRO ERECT IN SLAVE MODE
FAST ERECT SYNCmay be activated in air to perform a
fast Heading error resetting in a magnetic sterile area.
LRC
CCALCCAL
This is a MAINTENANCE FUNCTION
Don’t go there!!
LRC
COMPASS CALIBRATION MODELest ye be tempted
COMPASS CALIBRATION MODELest ye be tempted
• Once CCAL begins it MUST be completed!!! (You don’t know how)
• CCAL is ONLY used on ground.
• You CAN NOT get out of CCAL using the MODE select button!!!
•HOLD THE CONTROLS!!!!!!• (you don’t why but it can be ugly!)
•FOGS CAN NOT BE ZEROIZED after initial calibration.
LRC
COMPASS CALIBRATION (CCAL)
MODE COMPASS CALIBRATION (CCAL)
MODE • IN CCAL MODE THESE FUNCTIONS ARE
ENABLED:
• COMPASS CAL START• COMPASS CAL STORE• COMPASS CAL COEFFICIENTS READ• COMPASS CAL COEFFICIENTS WRITE• BIT STATUS REQUEST• BIT HISTORY REQUEST• INDEX SET REQUEST (NEVER CHANGE!)• ETI GET REQUEST
If you don’t know what this means – why are you in CCAL?
LRCCCALCCAL
• Changing the index WILL degrade YOUR SYSTEM!
• DO NOT “PLAY” WITH THIS TOOL
• THE ONLY WAY TO RECOVER FROM A BAD CCAL IS TO PERFORM ANOTHER CCAL
• LOG Index # AFTER CALIBRATION.
LRC
?? QUESTIONS ???? QUESTIONS ??