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.

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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

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InterconnectionsInterconnections

•FLUX VALVE •NAVIGATION SET, AN/ASN-

128•HSI•VSI•AFCS

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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

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CN 1716

CN 1716

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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)

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SENSOR ELECTRONIC UNIT (SEU) GENERAL VIEW

SENSOR ELECTRONIC UNIT (SEU) GENERAL VIEW

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“SEU” aka “FOG”AHRU CN-1716/A

“SEU” aka “FOG”AHRU CN-1716/A

23

087-

027

LRCBeforeBefore

Compass Controller

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DIGITAL CONTROL PANEL (DCP)

DIGITAL CONTROL PANEL (DCP)

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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

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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.

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• 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

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After 45 seconds:• the SYSTEM will automatically default to

the SLAVE mode• and the VSI ATT warning flag disappears

AC Power AppliedAC Power Applied

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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

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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)

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““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.

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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

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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.

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CCALCCAL

This is a MAINTENANCE FUNCTION

Don’t go there!!

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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.

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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.

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?? QUESTIONS ???? QUESTIONS ??