A lot of work has been on going on 579 the past few months. To start with investigation has been on going into an intermittent problem with the Battery Master Switch, this has on several occasions failed to supply battery power to the aircraft and after checking out and replacing an intermittent battery master contactor and a loose crimp on the master switch the problem has been pin pointed to a slightly dislodged pin in a multipole connector on the aircraft side which will require the ejector seat to be removed and will be tackled in the next month once the weather has settled, a couple more pre existing problems identified and fixed.
The L/H brake pack has been replaced after a leak, attributed to a damaged helicoil insert on the pressure line fitting to the pack. A new pack has now been built up, refitted, bled and function tested satis. The removed brake pack will go back into store and a new helicoil will be fitted in time giving us a serviceable spare.
The Bi-furb or spray mat heater has been refurbished after delamination of the paint due to corrosion. This has now been removed and treated, luckily the heater elements were found not to be damaged and once a checked out and a new coat of paint applied it has now been refitted.
The team took a week off work in Feb to tackle many of the remaining on and off aircraft tasks identified from the Form 700s as outstanding and it was just our luck that that particular week just happened to be the time the snow and a week of bitter winds and sub zero temperatures arrived.
Not to be put off the first job was to sweep the aircraft and surrounding ground clear of snow. Work then began rebuilding a replacement Air Turbine Gearbox (ATGB) assembly, having removed a previously refurbished item as we were unhappy with the level of vibration, the cause of which has been identified and this will again be stored as a spare. With the impellor heated and pressed onto the matched shaft, the rest of the nozzle vane assemble was put back together and the link arm from the governor adjusted and set to rig. It was then time to lug the ATGB through the airframe, fit it and mount the generator and alternator followed by plumbing in all the supply and cooling air piping.
Hot air from our air start was applied to function test the ATGB and get the oil levels correct. The No 1 and 2 engine bleed air connections along with the Reheat Air Motor Control Unit pipes were blanked off and hot air applied to the aircraft. The previously mentioned ATGB nozzle vane governor link was left disconnected and manually actuated to slowly spin up the gearbox to prevent it being shocked into full on load condition straight away. The ATGB was gradually opened up to full on speed level and no vibrations or leaks were found, gearbox install signed off satis.
With the ATGB installation complete this allowed for the reinstallation of the No 1 Interpipe, with a few more bodies available to man handle the pipe in, it was slid into position on its rollers another big piece of the puzzle refitted.
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