The Chipmunk remains dormant as various components are being serviced in workshops. The rear fuselage is firmly tethered twixt trestle and weighted strops to keep the airframe steady during engine and tail plane removal and replacement.
At the end of the month a specialist from the RAF will be on site to supervise the final phase of the X-ray inspections which involves local staff and kit in a conversion to Computerised Radiography.
Work has been progressing well and has been ground run for the first time this year and all is well apart from the wheel brake system which is not holding adequate pressure. This system is charged by a small single cylinder compressor driven from the engine gearbox at around 1200 RPM It is mounted on the starboard side and sucks in air through a spring loaded valve and gauze filter. The compressed air is delivered to the large storage bottle on the port side via a smaller bottle (black with brass label) and non-return valve
This small bottle is a reservoir for castor oil and when the system is charged to 210 PSI, pressure equalises and allows a small quantity of oil to feed back to lubricate the compressor which is in effect a 2 stroke unit. The oil therefore not only lubricates the ring-less compressor piston but also gets to the bearings in the crankcase via the transfer port. The maintenance team plan to remove the compressor which is reasonably accessible, spin it up on a lathe and check the output and if necessary replace it with a spare unit. If it proves to be serviceable then the oil bottle and non-return valve will be removed and inspected.
The first flights for W5856 have now taken place and these will provide refresher training for the aircrew as well as completing trials of the recently installed Powered Flight Alarm system (PFLARM). These trials will be conducted against a 727 Naval Air Squadron Grob 115E Tutor also based at Yeovilton and verify that both aircraft can detect each other using their IFF based electronic collision avoidance systems. To provide good transmission and reception of signals W5856 has 2 PFLARM aerials; one beneath the lower fuselage and one on top of the upper wing. The top aerial of this very modern kit is fitted just in front of a component that stems from the early history of this naval aircraft. Under a blister panel there is a hoisting ring attached to the 4 leather clad strops seen below the wing and attached to fuselage hard points at the aircrafts centre of gravity. This lifting arrangement is sometimes used today for maintenance purposes.
In the past the lifting gear allowed for hoisting aircraft on board carriers from lighters and also Swordfish floatplane operations from battleships in the 1930’s and 40’s.
The Sea Fury T20
The aircraft is completing its winter maintenance period at Weald Aviation and is planned to be back at Yeovilton in April. During the winter maintenance period the aircraft has undergone a 25 hr inspection, a Mode ‘S’ Transponder upgrade and an Engine Oil Grade Change as advised by Rolls-Royce. Additionally, the aircraft was re-weighed to correct a C of G anomaly following the airframe repairs and Engine rebuild. She is now in a good position to commence the 2018 Flying Display Season and will be recovered to RNAS Yeovilton early April.
The Sea Vixen
Work continues to develop the sheet metal repair schemes required to repair the aircraft and these will need to be approved by a CAA accredited A8-21 Design Organization.
Currently the team are inspecting the removed engines to confirm their serviceability following the wheels up landing, which includes removing the top half of the compressor casing to inspect the rotor and stator blades of the compressor. All indications to date are that the engines are good, but further maintenance operations / inspections are required to complete this work package.
After Easter the team will commence the second of the revised Annual Inspections which will aim to preserve and maintain the aircraft in preparation for the commencement of the sheet metal repair work.
Work continues in the back offices to return the FB11 to flight and the engine for the Swordfish LS326 is being rebuilt offsite. The Seahawk WV908 is in dry storage to aid preservation.
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