Presentation on theme: "Fiber Optic Gyro System (FOGS) (AHRU)"— Presentation transcript:
1 Fiber Optic Gyro System (FOGS) (AHRU) New EquipmentCN-1716/AFiber Optic Gyro System(FOGS)Attitude Heading Reference Unit(AHRU)
2 CN-1716 (FOG) New Equipment will replace the three existing gyros ASN-43(Direction Gyro)CN-1314 (Vertical Gyro)and TRU-2A/A (Rate Gyro)
3 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.
4 How FOGS WorkFiber Optics for Axial Reference replacing the mechanical gimbaled gyros.Accelerometerselectromechanically compensate & stabilize in flightAHRU is a self latitude look up system.Flux Valve provides initial reference in heading- Post CCAL, flux valve provides updatesFOGS filter fluctuations of flux valve whichsmoothes out the pitch, roll, and heading output.
5 “FOGS” AHRU CN-1716/UH-60 Gyros Replacement New Digital ControlImproved display and control capabilityImproved maintenance and diagnostics functionsSpec 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
16 CCAL = Compass Calibration Digital Control PanelDisplayWindowDG MODEIndicatorCCAL MODEIndicatorAlignment ModeIndicatorFailureIndicatorSLAVED MODEIndicatorMODESelectorFunctionSelectorDisplay CursorMovementEnter SelectionButtonCCAL = Compass Calibration
17 !! LOWER CONSOLE lights have to be ON !! AC Power AppliedInitial power on: All lamps illuminate for 2.5 seconds.!! LOWER CONSOLE lights have to be ON !!- DCP performs a lamp self-test / system MOC.
18 Turn Lower Console lighting rheostat on to illuminate DCP. NO DISPLAY?Turn Lower Console lighting rheostat on to illuminate DCP.
19 AC Power Applied ALN lamp will be on Initial power on: DCP is performing lamp self-test for 2.5 seconds, THEN:ALN lamp will be onATT fail flag on the VSI will be in viewAHRU will align and self-test within45 seconds
20 AC Power Applied After 45 seconds: the SYSTEM will automatically default to the SLAVE modeand the VSI ATT warning flag disappears
21 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.
22 Starting ProcedureStep 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.
23 Step 1. Mode Selector – As desired. (Continued) Starting ProcedureStep 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!!
24 Call Maintenance Starting 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
25 FailuresIf 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 lightIf the fail light clears – continue missionIf fail light does NOT clear – Call maintenance
26 ELECTRICAL POWER CHARACTERISTICS A Primary power interruption of less than 200 milliseconds does not cause a system realignment.Power interruptions more than 200 MillisecondsCAUSE SYSTEM IN-AIR RE-ALIGNMENTThe 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)
27 “Hold the Controls” NOTE During aircraft shutdown, when engine power control levers are moved from the Fly to Idle position, orwhen the generator switch position is changed to off, andelectrical 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.
28 If the Collective Position Sensors are out of null CLTV NULL = YAW DRIFTIf the Collective Position Sensors are out of nullthe aircraft will have agreater tendency to yaw at hoverthan with the older system.
29 especially if you have seen fail light YAW DRIFTWrite it upespecially if you have seen fail light
30 GYRO ERECT IN SLAVE MODE FAST ERECT SYNCmay be activated in air to perform a fast Heading error resetting in a magnetic sterile area.
31 This is a MAINTENANCE FUNCTION CCALThis is a MAINTENANCE FUNCTIONDon’t go there!!
32 COMPASS CALIBRATION MODE Lest 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.
33 COMPASS CALIBRATION (CCAL) MODE IN CCAL MODE THESE FUNCTIONS ARE ENABLED:COMPASS CAL STARTCOMPASS CAL STORECOMPASS CAL COEFFICIENTS READCOMPASS CAL COEFFICIENTS WRITEBIT STATUS REQUESTBIT HISTORY REQUESTINDEX SET REQUEST (NEVER CHANGE!)ETI GET REQUESTIf you don’t know what this means –why are you in CCAL?
34 CCAL Changing the index WILL degrade YOUR SYSTEM! DO NOT “PLAY” WITH THIS TOOLTHE ONLY WAY TO RECOVER FROM A BAD CCAL IS TO PERFORM ANOTHER CCALLOG Index # AFTER CALIBRATION.
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