After a huge amount of work the starboard inner flap repair is complete apart from a small panel (Picture 1) on the wing upper surface.
Following extensive rigging checks, pressure was supplied to the green hydraulic system from a ground rig, the wings were spread (Photo 2) and full functional checks of the flaps were carried out.
The original cause of the failure was a snapped bolt which connects the chain drive to the operating arm of the inner flap. This arm when travelling back and forth also has to rotate slightly in its mounting to the flap (photo 3)
and this movement was restricted on the damaged side. Both sides have now been dismantled and lubricated and an additional check has been added to the servicing schedule to avoid future problems. The maintenance team are up to strength with 2 new members and are getting on with the rest of the winter servicing which includes a deep inspection of the Port engine (photo 4)
Later they will jack up the Sea Vixen and do full functional checks of the Blue and Yellow flying control hydraulic systems and the red system for the hook, speed brake and emergency undercarriage lowering. By March the aircraft should be fully re-fuelled and ready for some ground running.
After a 600 man hour maintenance package the Chipmunk took to the air straight after main leave on the 4th of January. However there were some radio and IFF problems which Fraz the Avionics Supervisor traced to faulty connections and these were carefully replaced. For the rest of the month serviceability has been excellent and WK608 is frequently out on the line and getting the display pilots ‘back in the saddle’.
The engine remains partly dismantled following the last piston check as some damage has been detected on the exhaust valves. The lower three pistons have been replaced (photo 6) and safely hang free with rubber padding in place but the others will be fitted later with their cylinders. The large stemmed valves fitted to the later engines are sodium filled to help transfer heat from the valve head to the cylinder head via the stem and valve guides. They also have a special coating on the combustion chamber side of their heads to improve heat tolerance and this coating was found to be wearing away from the rim of the valve heads.
It was therefore decided to fit the spare set of 18 new exhaust valves. Interestingly the valve seats which fortunately are in good condition are machined at 1° wider inclusive angle to the valves so as to accommodate the slight change in the shape of the valve heads when hot and provide a perfect gas tight seal.
All the Swordfish winter maintenance is complete apart from some more X –ray NDT on the undercarriage using the latest digital equipment. First the NDT team have to create reference files for the various parts that are to be inspected and a spare set of undercarriage legs is being used for that. The engine reassembly and all other work is scheduled to be completed by late March, ready for the new flying season. In common with last year the programme will be carefully tailored around 15 hr piston checks which will continue for the time being.