Calibration of Compass of Back-up Heading and Atti...

Calibration of Compass of Back-up Heading and Attitude System

1.Equipment Needed

A 28V ground DC power source.

2.Preparations

Connect the 28V ground DC power source with the helicopter.

3.Testing Procedures

(1)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 is required upon replacement of processor of the back-up heading and attitude system.

·Compass calibration shall be conducted after the back-up heading and attitude system passes the power-on check.

·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.

·Power system shall not be switched off during the calibration,or it will generate great error in magnetic heading.

(2)Check and Calibration.

Preparations:

·Place the helicopter on the calibration site.

·Unlock the control system of the helicopter.Set all movable devices such as control mechanisms,rudder pedals,cyclic pitch levers and collective pitch levers at neutral positions(cruising flight positions).

·Switch on all airborne electrical devices and make sure they work normally.

Compass Calibration:

·Set the calibration switch on the processor of back-up heading and attitude system rightward to“CALI.”position.

·Power on the helicopter and the needle of HSI(horizontal situation indicator)keeps turning clockwise nonstop,indicating that the system is being calibrated.

·When the system is being calibrated,push the helicopter for 2 rounds at a constant speed on the calibration site(720 degrees).Each round shall cost not less than 1 minute.

·Put the calibration switch on the processor of back-up heading and attitude system leftward to“NORM”position.

·Wait until the needle of HSI stops turning(heading is 0 degree),calling an end to the calibration.Then power off the helicopter.

4.Finishing Touches

Switch off all live devices and remove the GPU.