INNOVATIVE METHODOLOGY OF INCREASING RESISTANCE IN THE OUTPUT LINE OF PRESSURE TRANSDUCER TO CALIBRATE AND CARRYOUT FUNCTIONAL TEST OF OXYGEN INHALE INDICATOR WHICH FUNCTIONS AS VISUAL INDICATION OF OXYGEN SUPPLY TO MASK OR PRESSURE HELMET OF PILOTS

摘要

The oxygen system has been designed to ensure normal breathing of the pilot and to retain his working efficiency throughout flight envelope as well as during emergency bailout. The system provides excessive pressure to the breathing system and in the tensioner bladders of the high altitude pressure suit / Anti G suit (to reduce +g influences which originates during aircraft manoeuvres). The excessive oxygen pressure in the breathing / suit lines is regulated automatically depending upon flight altitude / G-loads. Oxygen inhale indication has been provided to provide visual indication of oxygen supply to mask or pressure helmet. This is achieved with the help of pressure Transmitter . Pressure Transmitter is installed in front and rear cockpit. It provides necessary data to indicate pilots breathing when the oxygen is supplied from aircraft oxygen system. The transmitter senses the pressure difference (mainly suction during inhalation) in the output line of Oxygen Supply regulator for each pilot during breathing and accordingly provides electrical signal to multi functional warning system. On multi functional warning system indicator shows changing of variable length vector:- Upon inhalation and continuous oxygen supply the horizontal hairlines on black background which changes along the width of indicator (voltage more than 1.5 V) Upon exhalation and without oxygen supply the fixed vertical blue hairlines on black background (voltage less than 1.5 V ) In the test flying of aircraft Oxygen annunciating starting, on ground or below 2 Km cabin altitude, in front cockpit or in rear cockpit or in both cockpits repetitively occurred .It was deduced that this was caused by higher output voltage sensed by pressure transducer . The output voltage generated by pressure transducer can be reduced to required levels by introducing resistance between armature and primary & secondary coils The four screws were loosened and the primary and the secondary coils were adjusted to give required voltage, (fig-1) Thus error Continuous oxygen inhale indication on ground or below 2 km of cabin altitude is due to more output voltage provided by pressure transducer . The output voltage provided by pressure transducer is reduced by introducing resistance between armature and primary / secondary coils. After adjustment the performance of the sensor was found satisfactory at test setup in resource test laboratory.