Improved Slushing Procedure For Hydraulic System Pipe Lines Of Lca

Abstract

Hydraulic system of LCA aircraft consists of two independent circuits, with a completely separated piping for feeding the tandem boosters of the FCS actuators. System 1 powers one side of the tandem boosters of the FCS, the leading edge slats and normal operation of the utilities. System 2 powers the second side of the tandem boosters of the FCS, the airbrakes and the emergency operation of the utility services. In order to achieve good system performance and to meet the production target, it is required to be kept clean and the system has to be slushed within short span of time. To achieve this hydraulic slushing procedure developed with three setups and it includes standard methodology to bypass LRUs.

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DESCRIPTION

TECHNICAL FIELD

The invention describes a comprehensive procedure for slushing of hydraulic system pipe lines with three setups and to develop a standard methodology to bypass the LRU's of the hydraulic system.

BACKGROUND OF INVENTION

Hydraulic system of LCA aircraft consists of two independent circuits, with a completely separated piping for feeding the tandem boosters of the FCS actuators. System 1 powers one side of the tandem boosters of the FCS, the leading edge slats and normal operation of the utilities. System 2 powers the second side of the tandem boosters of the FCS, the airbrakes and the emergency operation of the utility services. In order to achieve good system performance, it is required to be kept clean. Hydraulic system after installation on the aircraft is required to be slushed thoroughly in order to remove the contamination in the system fluid and bring the cleanliness level of the system to class 7 or better of NAS1638. This slushing was carried out on the aircraft with 13 setups and there was no standard methodology for bypassing the LRUs in the hydraulic systems. Because of these reasons it used to take more lead time for slushing of hydraulic system pipe lines. To reduce the cycle time for slushing of hydraulic system developed comprehensive procedure for slushing of hydraulic system pipe lines with three setups with standard methodology of LRUS bypassing.

SUMMARY OF INVENTION

Comprehensive slushing procedure is developed for hydraulic system pipe lines with three setups with standard methodology of LRUS bypassing.

DRAWINGS

Fig 1: Hydraulic pr.switch & H.P filter Equipped in Systen-lcircuit.

Fig 2: Hydraulic pr.switch & H.P filter Equipped bypassed in Systen-lcircuit.

PROCESS DETAIL DESCRIPTION:

General slushing procedure:

After installation of hydraulic system pipe lines on the aircraft it is required to be slushed thoroughly in order to remove the contamination in the system pipe lines and bring the cleanliness level of the hydraulic fluid to class 7 or better NAS 1638. Generally before carry out slushing, all LRUs have to be bypassed as selected in pre defined circuit in the hydraulic system. Set the hydraulic system ground trolley to trolley reservoir mode, connect the hydraulic system ground trolley pressure line to 'IN' and trolley return line to "OUT". Gradually increase the pressure to 60-75 bar. Circulate the fluid for 30 minutes. Check the contamination level and repeat the above said for every 15 minutes until to bring the cleanliness level of the system to class 7 or better NAS 1638. Fluid used in the system is MIL-PRF-5606.

The slushing carried out for the LCA hydraulic system pipe lines are with 3 setups and standard setup was developed for bypass the LRUs which are explained below in detail. Improved slushing procedure for hydraulic system pipe lines of LCA:

1. Bypass the LRUs: LRUs are bypassed with hoses, end caps and standard fittings/unions. For example to bypass the H.P filter in the Syetem-1 circuit , H.P filter replaced with hose of 98 cm length and one end of this hose contains 90 deg. angular female fitting and another hose end contains straight female fitting with two unions/fittings and it was shown in Fig.l & Fig.2. These unions/fittings are connected in between pipe lines/fittings and hoses. To bypass the pressure transducers, pressure switches and for some of the LRUs hoses are not required and for these LRUs directly replaced with standard End caps and standard unions/fittings.

2. Setup-1:

i) In this setup bypass the LRUs which are involved in Sytem-1 circuit of the hydraulic system and follow the bypass the LRUS as per Syetem-1 enclosed fittings/unions, end caps and hoses.

ii) Set the hydraulic system ground trolley to trolley reservoir mode and connect the hydraulic system ground trolley pressure and return lines to their corresponding ports on the aircraft. iii) Gradually increase the pressure to 60-75 bar. iv) Circulate the fluid for 30 minutes. v) Repeat the steps iii & iv to check the contamination level for every 15 minutes until to bring the cleanliness level of the system to class 7 or better NAS 1638.

3. Setup-2:

i) In this setup bypass the LRUS which are involved in Sytem-2 circuit of the hydraulic system and follow the bypass the LRUS as per Syetem-2 enclosed fittings/unions, end caps and hoses. ii) Set the hydraulic system ground trolley to trolley reservoir mode and connect the hydraulic system ground trolley pressure and return lines to their corresponding ports on the aircraft. Hi) Gradually increase the pressure to 60-75 bar. iv) Circulate the fluid for 30 minutes. v) Repeat the steps iii & iv to check the contamination level for every 15 minutes until to bring the cleanliness level of the system to class 7 or better NAS 1638.

4. Setup-3: In this setup bypassing the LRUS not required because in this set up has to slush the pneumatic lines and these lines slushed by air with help of pneumatic air gun.

CLAIMS

We claim slushing procedure of the LCA hydraulic system pipe lines.

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