Navy Wings Hangar 15 February Oily Rag

Sea Vixen

Maintenance of the Port Avon engine has been completed and the compressor top cover replaced

 This required plenty of care and precision to mate the two halves of the casing whilst making sure the stator blades did not slip out of their retaining grooves.  The bolts (red arrows) are a tight fit to ensure alignment and took time to fit and torque correctly.  An external inspection of the engine identified a broken bonding lead to a fuel line (blue arrow) feeding the intake guide vane actuator.  These lines have several rubber O ring seals and need to be bonded to ensure no rogue electrical charges build up.

 

 

 

‘Photo 2’ shows the fuel line with the broken lead attachment tab and a serviceable spare.  As with many replacement tasks the team faced the old problem of sourcing the consumable spares and fortunately replacement O rings were available.  The lifting gantry has been occupied supporting the Swordfish whilst the main landing gear was removed for Non Destructive Testing but is now available and the Avon engine will be refitted soon. The Sea Vixen team have also completed all the hydraulic system functional checks, during which it was noticed that the tail trim tab was not quite right with flap selection.  This tab is cross connected to the flap system so that on half and full flap selection the tail plane automatically adjusts to correct the aircraft attitude, reducing the control input load for the pilot and assisting in a smooth recovery.  Landing this heavy historic aircraft needs skill for another

reason; the tyres are an expensive commodity and the new stock  needs to be conserved.  Sea Vixens normally adopt a nose high attitude after touch down to slow the aircraft aerodynamically and save the brakes.  The bottom of the tail booms are fitted with a pair of sacrificial rubbing blocks which are designed to limit the rotation when they contact the runway surface and those who were at RNAS Yeovilton in the 70’s will recall the showers of sparks during night recoveries.  However the practise of scraping runways is not encouraged especially if you are landing at another airfield, therefore the pilot needs to land close to the threshold to spare the brakes and tyres.

 

 

Swordfish W5856.

Following the undercarriage Non Destructive Testing, the struts have been refitted and the wheels have assumed a curious camber as the aircraft is much lighter than normal with the prop,cylinders and many other items removed.  The prop is a really big assembly with the solid alloy blades sandwiched between the hub halves.  In ‘Photo 5’ 
Andy is refitting the fairings that protect the brakes.  The team are still awaiting a spare set of exhaust valves and the barrels are ready with the intake valves installed (Photo 6).

With the forward fuselage panels removed the large main fuel tank is exposed and the struts and straps that hold it secure can be seen (Photo 7).  A second smaller tank lives behind the main tank and just in front of the instrument panel.  In normal flight the carburettor is fed via a pumped supply but if the pump fails the smaller tank provides a gravity feed and can be replenished from the main tank by using a hand pump located next to the pilots right hand which can also be reached by the rear crew should the pilot need assistance. Selection of the various fuel feeds is via a pilot operated valve on the starboard side 

Whilst awaiting the engine rebuild the team are attending to other tasks such as gathering together the spare oil coolers  and finding a specialist to rebuild them.  They are mainly soldiered copper and brass and running repairs, such as were necessary last season, are difficult, as heat applied to solder a repair is apt to travel and melt adjacent joints.  There is also a repair in progress to an elevator horn where an “oilite” bush was found to be a bit loose.   These are made from self-lubricating, oil impregnated sintered bronze and the team are sourcing replacements and approval for the repair scheme which may involve reaming new bushes to the correct fit for the stainless steel sleeve that rotates within them.  There are two horns to each elevator but for now this is the only one that needs attention.