Section 16
Brake system refurbishment.
To assist
in arresting the aircraft during runway slowing down, the Lightning is fitted
with a basic hydraulically powered braking system. The system comprises.
1)triple
disc rotors (3 per side)
2) Pads
3)Drum piston
assembly
4)Dunlop
brake control unit and cable
Each drum
piston assembly, is powered by the hydraulic services circuit @1750 psi, in
order to facilitate stoppage of rotating discs, and therefore wheel, by way of
brake pad pressure/friction.
Control of
the drums is by way of a Dunlop brake control circuit, directly attached to a
basic tension cable attached to the pilots control stick. Directional control
is achieved via the rudder pedals, in direct circuit with the brake control
unit. Hence differential breaking is achieved.
ZF579’s
brake control system is complete, though brake units require complete strip
down and clean up, brake lines renewed, Dunlop control unit checked for
operation, and pilots control cable replacing.
01/08/2005
Stage one
was to refurbish the brake units themselves. This involved choosing the best
set with least wear. Most Saudi sets were in excellent order, since they
performed one landing only on return to the UK. See below plates for unit
re-furbishing
.
Above: Brake
unit before, refurbishment. Although looking grotty, the pad and disc
dimensions are excellent, as were all units we inspected. 01/08/2005
Above.
Discs and pads being taken apart, to reveal typical surface corrosion.
01/08/2005
.
01/08/2005
Above. One prepared
earlier! A completed unit ready for fitment.
01/08/2005 Above: s/b axle stub being prepared
for fitting of refurbished wheels, new tyres, new maxaret units, new brake
lines, walking joints, new walking joint seals and refurbished brake units.
Above. One
s/b brake unit offered up for fitment. Note the wire locking. This is used to
stop the brake hub nuts loosening themselves.
Above. An
unusual view of a Lightning brake system. New lines, test points installed.
Above:
Another unusual view! Came back from lunch, and the aircraft was up on jacks
and some tea leaf had swiped our alloys!!
Above: OK,
so a jokes’ a joke, but now lets ‘have em back’, all of em!!
Stage
2. as @10/08/2005
Stage 2, is to remove the canopy, ejection seat, and replace the brake control cable, which is currently unserviceable. This will take place shortly. Completing the braking system refurbishment. Brake lines were renewed during gear bay restoration.
Stage 3 @ 08/2007-09-11
Stage 2 has been progressing slowly but surely. After removal of the ejection seat and canopy, the cockpit floor structures were removed, and the unserviceable brake control cable and valve were removed. The cable was found to be non effective for repair. Speedy instruments ltd were engaged and a new control cable was manufactured to original specifications. I monor fault was rectified with the control valve, enabling it to be re-installed into the airframe.
The new brake cable is ready to be fitted, on completion of the cockpit control surface gear refurbishments being completed.
Above: cockpit floors removed to gain access to control gearing and brake cable. Plenty of dust, dirt and grime, along with one or two rusty nuts from water ingress, but on the whole very good. No corrosion at all was indentified anywhere in the primary or secondary structures, or panelling.
Above: Tail plane gearing before removal. Other than dirt, grime and surface rusted bolts, all in great condition. The brown colour is sealant. The entire under floor structures are sealed with a tough moisture resistant sealer, which has kept the structures in as new condition, even after water immersal.
Above: One VERY unhappy Bowden brake control cable. Other than being used as a pattern, this cable will never see service again.
Note: the break in the cable assembly on the right of the photo. This was caused by water ingress, bursting the cable.
The old cable was sent off to Speedy instruments Ltd as a pattern, and several weeks later “voila” a nice new brake cable (on the right) was sent back.