Section 6
Hydraulics
Part 1 Pre restoration 07/2001
The hydraulic systems are effectively the life blood of the aircraft, providing the power of movement to all controls surfaces, alighting gear, air brakes and canopy controls. The Lightning’s systems are comprised of three separate hydraulic circuits, incorporating triple redundancy and emergency operation via Nitrogen accumulators. Main line pressure is provided by hydraulic pumps, driven by the ECU accessory drives. Functionality can be re-directed on failure of one engine, so that pressure is maintained from the remaining engine. 3 separate circuits are;
(1) Services Circuit:
Directing pressure to the following services.
Alighting Gear
Air Brakes
Wheel Brakes
Canopy
Flaps
Gun Pack
(2) No1 controls circuit.
Controlling the following.
(3) No 2 controls circuit
Controlling the following
Currently, most Hydraulic pipes, unions and accumulators are present in the rear fuselage as the rear of the aircraft forms one whole section during transportation.
Since the aircraft was dismantled for transportation, the following hydraulic pipes, unions and micro filters have been removed from the following areas, where each EF number represents one pipe or union.
Inboard trailing edges port and s/b (flaps, ailerons, wheel brakes and gear selection)
EF3 73 7589 EF3 73 367
EF3 73 349 EF3 73 369
EF3 73 351 EF3 73 385
EF3 73 339 EF3 73 371
EF3 73 345 EF3 73 361
EF3 73 341 EF3 73 329
EF3 73 343 EF3 73 327
EF3 73 729 EF3 73 325
EF3 73 725 EF3 73 321
EF3 73 303 EF3 73 323
EF3 73 301 EF3 73 715
EF3 73 305 EF3 73 363
EF3 73 307 EF3 73 717
EF3 73 309 EF3 73 365
Port S/B
Port and S/b no1 engine bay (Flaps, wheel brakes, canopy, ailerons, rudder, air brakes, artificial feel units, chute jettison)
EF3 73 3481 EF3 73 3441
EF3 73 1509 EF3 73 3445
EF3 73 3443 EF3 73 3439
EF3 73 3433 EF3 73 3443
EF3 73 1507 EF3 73 3437
EF3 73 7365 EF3 73 3431
EF3 73 4645 EF3 73 1693
EF3 73 4643 EF3 73 3435
EF3 73 3454 EF3 73 2541
EF3 73 4641 EF3 73 1683
EF3 73 3439 EF3 73 1509
EF3 73 1239
EF3 73 3441 (All above no1 bay Aft) (All above, No1 Centre)
Star/b
EF3 73 2541
EF3 73 2547
EF3 73 999
EF3 73 3555
(All above No 1 engine bay forward frames 44 to 25)
Port and s/b transport joint
(Mostly nose services, such as canopy, gun pack etc)
EF3 73 3431 –H5 EF3 73 795 -H16
EF3 73 3435 –H6 EF3 73 4635 –H31
EF3 73 3441 -H9 EF3 73 7371 –H32
EF3 73 2541 –H34 EF3 73 2967 –H24
EF3 73 2545 –H35 EF3 73 3581 –H30
EF3 73 2549 –H36 EF3 73 793 -H15
EF3 73 3583 –H37 EF3 73 879 -H17
EF3 73 2969 –H25 EF3 73 893 -H18
EF3 73 3429 –H27 EF3 73 4611 –H11
EF3 73 897 -H19 EF3 73 3457 –H10
EF3 73 3427 –H26 EF3 73 1675 –H1
EF3 73 903 -H20 EF3 73 1677 –H2
EF3 73 2965 –H23 EF3 73 1679 –H3
EF3 73 775 -H12 EF3 73 3557 –H29
EF3 73 2779 –H22 EF3 73 895 -H33
EF3 73 2777 –H21 EF3 73 3437 –H7
EF3 73 7911 –H14 EF3 73 1693 –H4
EF3 73 781 -H13 EF3 73 3439 –H8
T pieces, unions and banjos
EF3 73 867(H38) (special T piece, connects H7, H17 and H34)
EF2 73 633(H39) (Special Banjo T assembly for H10, H21 and H20)
EF3 73 859(H40) (Special elbow for H18 and H4)
EF3 73 865(H41) (Banjo 4 way, connects H24, H35, H6)
EF3 73 7369(H42) (Banjo T sub assembly for H26, H9, H16)
All of the above pipes and their associated unions wire locking and security brackets will undergo re-installation in order to return (primarily) the services circuit to function. Controls circuits will be re-installed but not charged until engines are installed. Services circuit can be operated from the hand pump behind panel 75P; hence engines are not required to test.
After preliminary inspections, all piping is in good order, more importantly the threaded connectors are in good order too. Dirt ingress is limited to the extremities of the pipes (i.e. the last 2-3 inches at each end), this will be cleaned out with a degreasing agent, leaving traces to be picked up by the micro filters. Micro filters can then be removed and cleaned after initial installation. Wheel brake lines will require replacement since unions are corroded excessively, in their current condition they will facilitate leakage in the services hydraulic circuit.
Above, a small selection! Of the myriad of hydraulic and hot air pipes to be re-installed in to the airframe
Aft port engine bay after installation of services and control circuits (see part no’s above, jet pipe removed)
Installing s/b forward no1 engine bay hydraulics
Hydraulics begin to take shape in the port no1 engine bay during installation of the long services and controls pipe work, the hundreds of security clamps will be installed following installation of the piping. Note. The lack of the no1 re-heat pump and throttle linkage rods.
Above, No1 Engine bay aft, installation of hydraulic subsystems progressing, along with throttle rigging, which can be seen top right. Jet pipe installed.
Above. No1 engine bay (forward view). No1 reheat pump and hydraulic services installed. Throttle rigging also now installed.
The following pages’ plates show port side no1 engine bay at an advanced stage of hydraulic and subsystems installation, including, all hydraulic piping, no’s 1 and 2 throttle rigging and lost motion box, engine final throttle linkage and all relevant anti scuff locating brackets.
05/03
Currently all hydraulic services are re-installed for both no1. No2 engines bays and inboard main plane connections. Currently outstanding is to re-torque all connections and finally wire lock. All connections in no1 engine bay have been re-torqued and are currently in the process of being wire locked. Both gear and canopy selectors are now operating. Services circuit will be pressurised upon fitment of new undercarriage bay connections, these require replacement due to corrosion in the pipe couplings. Once services circuit is pressurised, controls circuits will undergo the same procedure.
Initially the circuits will be filled and bled, then pressurised only to approx. 500 psi, then in 150 psi increments and finally up to full capacity. Nitrogen accumulators will need to be recharged after circuits are filled. Examination of micro filters reveals that they are in excellent condition, with very little particle accumulation. This will help after initial charging, to remove impurities in the pipe extremities after disassembly.
Individual services will be tackled one at a time, starting with surface actuators and moving on to artificial feel units, wheel brakes and under carriage mechanism.
Ongoing work to the Gear bay hydraulics. All locks and valves in the gear bay circuit require removal for refurbishing, including the main retraction jacks. Though the gear leg oleos will not require refurbishment, the retraction jacks do. Retraction jack cylinders are in excellent condition, however the jacks themselves are heavily corroded. It is hoped that upon removal, the corroded areas of the pistons can be built up and lapped back for chromium plating. The majority of the s/b gear bay is now removed, including, shut off valves and all associated flexi pipes. It has been found upon inspection, that the flexi hoses are good enough to re-install, along with 95% of stainless piping and couplings. Shut off valves are good and just require light lubricant soaking to free up. Some 5% or so of steel pipe couplings are borderline, hence they will be cut off, replaced and pipes re-flared with a 36 degree pipe flaring tool.
Both the main undercarriage link arms, radius rods and main pivot pins/assemblies will also require removal and restoration, since all have ceased. Main leg pivot pins also require greasing and restoration. This will all be removed. See below.
See below plates.
Above:- Flexi hoses and Dowty shut off valve, before removal.
Above: The same region with Dowty valve removed for refurbishment.
S/B gear bay before removal of retraction equipment and lower stress skin
Above plate shows retraction jack removed along with Dowty valves and most flexi hosing. (This plate clearly shows the removal of inner strengthening skin and the corrosion to be removed from underneath) Removal of the above components also now allows access to the S/b fuel booster pump. All lines have been blanked to stop impurities entering the hydraulic circuit.
Starboard retraction jack removed, corrosion on jack surface can be seen. Corrosion will be removed using HCL solution, old plating striped, then jack will be re-plated with copper and zinc electroplating.
08/03 S/B Retraction jack dismantled (see below plates), jack sent to workshop for chemical strip and hard chroming. Seals found to be in excellent order, though they will be replaced anyway. Internal machining of the jack cylinder in excellent condition, though the outer casing will require corrosion treatment and re-painting.
25/10/04 main gear retraction jacks returned from electroplating. Re-plated to original materials specs @ 1.6 inch diameter. See below plate.
New seal kits to be installed for each main jack.
30/08/03
S/board radius link elbow coupling and pin removed.
Main leg end knuckle joint freed up and greased
Radius link arm elbow joint bearing removed.
Upper radius rod link arm geometric down lock removed for restoration
Upper radius Rod main saddle pin and bushes removed, along with radius Rod.
Saddle pivot bearings cleaned and greased. Radius rods taken to work shop for refurb.
Geometric down lock pressure line removed from radius rod.
Undercarriage micro switches removed for restoration
Undercarriage bay magnesium castings striped and corrosion treated.
See below plates
=
Upper and lower Radius rods separated and main pin removed.
Above: Main saddle block bearings, ready for clean up.
Above :-Undercarriage, upper radius rod link removed
Same link rod. Bearings cleaned up.
Above: Main Upper radius rod Pivot removed and restored, ready for re-fit.
Below: Radius Rod re-furbished with new A25 bolts and hydraulic clips.
Above: Geometric Down lock removed and dismantled.
Above: The same down lock restored, ready for re-attachment.
Above: Main leg pivot freed up, greased and serviceable.
Above: Micro switch indicators removed for replacement.
Magnesium castings shot blasted to remove corrosion.
05.2004
New flexi hose and stainless brake pipes manufactured to original material specifications to be installed primarily into the starboard gear bay.
New brake lines installed.
05/2004
Below. Retraction jacks taken apart to be sent for grinding and electroplating.
Below. Cylinder bead blasted and corrosion removed ready for re-painting.
all jack seals will be replaced before re-installed to the hydraulic circuits.
Above. Same cylinder primed and ready for original paint finish
05/02/05 Above: Starboard gear bay refurbished and all components installed
Below: pressure and return line brake pipes and maxaret units refurbished.
Above. New blocks, caps and pipes installed.
08/2004. Upper radius rod installed into starboard gear bay, along with retraction mechanism knuckle assembly. Installed, torqued, greased and wire locked. Retraction mechanism now free and serviceable for testing, when sequence valves and retraction jack are reinstalled.
Below. Upper and lower radius rods re-installed.
Below. Upper radius rod and knuckle, saddle joints reinstalled, after powder blasting and re-painting. Bushes and bearings wet assembled and greased in situ with pneumatic grease gun. Finally wax oiled to preserve.
Below. New hydraulic piping installed, along with security brackets and fair leads
Upper door fairing torsion link blocks, pins and roller bearings re-manufactured as close to original material specs as possible, due to corrosion.
Above: shows, new brake line flexible piping and brackets installed
All cabling and piping rigged as per topic 3 specifications. New witness markings applied. Aerospace stainless special jubilee clips modified for bracing of pipe work. All magnesium castings greased with Aeroshell grade 7. 1 coat wax of oil applied to all.
·
03/04/2005
· Gun pack removed and canopy hydraulic lines re-connected to services circuit. All Services circuit hydraulic lines in this area checked and wire locked.
· Inspection of complete services circuit carried out, no1 and no2 bays, and undercarriage brake lines, jack lines inspected. Line replaced where required.
· Flap jack pivots greased and replaced, flap bay services inspected and cleaned
· Air brake pivots and synchronisation mechanisms greased and manually exercised, hydraulic lines inspected.
Above groundwork carried out in order to return Services Hydraulic circuit to serviceability.
04/04/2005
· Front fuselage brake and nose services accumulators charge to 1500 psi with nitrogen rig.
· Services Hydraulic circuit charged with Aeroshell fluid 41 (om15 dtd585 equivalent).
After initial charging of the services circuit, canopy, wheel brake, flaps and airbrake services were checked for operation. One starboard flap jack was found to be leaking and required new seals, a minor problem was also encountered with the starboard air brake manual lock, which was also rectified via re-shimming. 2 minor leaks were rectified in the flaps down line no2 engine compartment. No further leaks, evident after inspection, services hydraulic circuit complete and serviceable, no further problems. See below plates.
Above. Air brakes deployed on re-activation of services hydraulic circuits.
Above: Similarly, air brakes extended. Synchronisation adjusted to eliminate latency.
Above: Canopy and air brakes exercised successfully.
All services circuits will now be tested via a mk4 Hydraulic ground servicing rig, in order that larger demands can be made of the hydraulic circuits and undercarriage re-
traction and extension tests can begin.
Similar checks will now take place on the Controls1 and controls 2 hydraulic circuits, in order to re-charge both circuits and test flying controls.