25-01-2013, 09:37 AM
HYDRAULIC BRAKE BLEEDING[HYDRAULIC SYSTEM]
HYDRAULIC BRAKE.docx (Size: 16.34 KB / Downloads: 27)
AIM
To prevent the brake failure during brake application and to keep the brake system always in serviceable condition
THEORY
The aircraft wheel brakes are designed to provide slowing down of aircraft on touch down and totally to stop the aircraft
It holds the aircraft while parking and during ground running of engine
The brake unit may be shoe type, disc type or multi disc type
By proper maintenance of brake unit the maximum flight accidents may be prevented
If the air is found in the hydraulic brake system brake will not be effective
So the presence of air is found in the hydraulic brake system is to be expelled from system is called BLEEDING OF SYSTEM
If air is not removed the brakes system will be spongy
To avoid that brake bleeding has to be carried out of regular intervals
OCCASION
On any periodic servicing as per lay down in servicing schedule
If any hydraulic brake detected from piston assembly of brake unit
Whenever pilot reports that the brake unit is slugging/spongy action of brake pedals
At the time of brake pipe renewal and topping up of brake reservoir
REQUIREMENTS
Man hour=3 hrs
Man power=3+1
Documents = aircraft servicing form, aircraft maintenance manual
EQUIPMENTS/TOOLS
Tripod screw/hydraulic or bottle jack
Bleeding hose
Clean container with specified hydraulic oil
Hand gloves
SAFETY PRECAUTION
Take proper precaution of jacking up of aircraft
Clean the serviceability of jacks
Jacking sufficient hydraulic oil in a cleaned container
Bleeding should be contained until no more oil bubbles are expelled from the system and fin brake pedal is obtained
PROCEDURE
There are two methods of bleeding the brake system, gravity and pressure methods. gravity method is described below
Jack up the aircraft with all necessary conditions
Remove the bleeder screw from the bleeding point on the brake unit, by cutting the locking wire
Connect one end of brake hose to bleeding point and other end of hose immerse in to the specified oil in small container
The fluid is then forced from the system of operating the brake pedals
Watch for the bubbles from oil which comes out from brake system through hose
Bleeding should be contained till hydraulic oil comes out without air bubbles
Fill the brake master cylinder with fresh hydraulic oil which has lost during this process
Apply the brake several times and check for any problem in brake system
Wire lock the bleeder screw
Lower the aircraft by taking proper precaution
Make necessary entry in the aircraft servicing form/log book
RESULT
The aircraft brake system bleeding is carried out and found satisfactory