Calibration of HJG-1A Magnetic Heading Sensor of H...
1.Equipment Needed
None.
2.Requirements
·Compass calibration is required before the helicopter is delivered from the factory or before the first flight after a large-scale modification on the helicopter.
·Compass calibration and zeroing is required upon replacement of the magnetic heading sensor.Zeroing is required upon replacement of the inertial measuring unit.
·The compass shall be calibrated on plain sites that are 200 meters away from steel-made mechanisms,underground cables,large metallic pipes,high buildings,high-voltage cables and any physical entities prone to induce changes to geomagnetic field.
·Airborne devices(accompanying devices,products and accessories)shall come with complete supporting devices and shall be properly placed.
·All airborne electrical devices shall be working normally before the calibration.
3.Preparations
·Place the helicopter on the calibration site.
·Switch on all airborne electrical devices and make sure they work normally.
4.Compass Calibration
(1)Compass Calibration.
·Press selector keys D3,R1 and L1 on MFCD to enter into the navigation page.
·Press“M-CAL”to enter the page for calibration of magnetic heading sensor(as in the figure below).
·Press“M-CAL”to start the calibration and“M-CAL:ON”would be displayed on the display.
·At the same time,push the helicopter for 1 round at a constant speed within 2 minutes.
·In 2 minutes,HNS finishes the calibration and“M-CAL:OFF”is displayed.
Note:The calibration result is classified into 9 levels.If the displayed result is“CAL LEVEL-X/Y:9”,HNS passes the calibration.If not,another calibration is needed.
(2)Warp Correction.
·After compass calibration,align the symmetrical axis of the helicopter with the 0° axis of the calibration site(magnetic heading:true north).
·Read the magnetic heading output by the magnetic heading sensor displayed on the compass calibration page for magnetic heading sensor.
·Calculate the value of warp.
·Press key selector“WARP”and input the warp correction value of magnetic heading sensor with MFK(multi-functional keyboard).For example,if the magnetic heading value of magnetic heading sensor(M-HDG)is 2 degrees,input 2;if M-HDG is 358 degrees,input -2 degrees.
·Press“ENT”to confirm and call an end to the zeroing of magnetic heading sensor.
5.Finishing Touches
·Put switches“INS”,“IDCS”and“HNS”at“OFF”position.
·Switch off all airborne live devices.
·Unplug the GPU.
Compass Calibration Page for Magnetic Sensor of HNS
M-HDG:Magnetic Heading
WARP:Zero Offset Correction Value of Magnetic Sensor
CAL-LEVEL-X/Y:X/Y Axis Correction Level
M-CAL:Magnetic Calibration Enabling
Note:The calibration ends automatically 2 minutes after being enabled.Press“M-CAL”again to stop the ongoing calibration.