Section 5

Engine Starting Wiring

As with all the wiring emanating from the nose section, and traversing the transport joint, engine start wiring is both unidentified and cut. Examination of all engine start components reveals the following.

Start buttons, relight buttons, engine master and ignition isolations switches are all in good order and functional mechanically. All the relevant circuits, to which the above belong, are incomplete since wiring has been cut, no identification is present.

Engine start control boxes (Type…….) for no1 and no2 engines have been inspected internally. Both are found to be in excellent order, and should require no servicing or repair. Likewise HF control boxes are in the same condition.

LP and HP ignition switches and solenoids. Some exterior corrosion is present but again internal condition is very good. Type t2 relays have not faired so well and condition will be revealed during functional tests. Contactors and fuse blocks (spine section) are also in good order. The condition of the HE ignition units is to be determined with further inspection. Wiring to the above components has been cut at the lower transport joint as well as the transport joint region in the spine. All cables (approximately 16 starting component cables) will require identification and re-connection. Engine harness cables and multipoles are missing altogether.

Despite exposure in the corroded spine equipment compartments, IPN tank, air pipes, fuel pipes and pumps appear to be in good order. Condition of the pumps will be established on re-connection of the starter circuits.

Relight time delay switches are also in excellent order and should not require any overhaul. Indeed the relight time delay multi pole connectors can be used to identify much of the start circuit wiring traversing the transport joint, by way of continuity.

All engine start fuses (Forward fuse box, port fuse box and dc feeder panel) have been removed for safety during wiring and electrical tests.

10/08/04

Goal: To re-connect all engine start wiring, in order to inspect and test all starting components.

Starting components comprise the following equipment

1) Engine master switch. Energises engine start circuits

2) Ignition isolation switches for n01 and n02 engine. Isolation for HE ignition circuits

3) Engine start push buttons. These buttons begin the timed starting sequence.

4) HE and HF ignition units. High energy and High frequency ignition boxes for main ignition and starting ignition.

5) Control Boxes. Both control boxes for no1 and no2 engine are located in the spine, and control the timed sequence of starting, through relays and time switches.

6) Starters. Avpin / Isopropil Nitrate (IPN) driven starter motors. 1 per engine.

7) Starter pumps. Feed air and fuel to the starters.

Starting Sequence

Upon switching on the engine master toggle, the starter circuits are livened via two control relays in the Spine section. These relays divert 28Volts via the control boxes, to energise the starter push buttons in the cockpit.

Upon pressing the relevant starter push button, 28V is fed via the contacts of the starter over speed switch, and via the relevant pins in the control box, to energise the time switch relay, via high and low pressure switches.

Energising the time switch relay in the relevant control box starts the time switch and DC motor in the control box, controlling the following timed start sequence.

The pump unit contactors are energised to start the AVPIN pumps, during which time a HP solenoid is de-energised, diverting AVPIN fluid back to the storage tank rather than to the starter motors, to allow pumped air into the starters and purge the combustion chamber.

At a pre-determined time, controlled by the control boxes, the HP solenoid is livened, to allow AVPIN fluid to be pumped through a low-pressure switch to the starter motor. Once fluid pressure in the supply pipe reaches the correct pressure, the low pressure switch contacts swap from pins A-B to pins A-C, directing 28V to the HF ignition circuits, and thus supplying ignition to the starter motors. Backpressure from the starter combustion chambers, then activates via HP switches, the high energy ignition circuits, allowing the engines to run up to speed. Once satisfactory engine speed is reached, an over speed switch on the starter motor operates, to disengage the starter and re-set the time sequence switch in the engine control box, ready for the next start.

Much of the wiring for the starter circuits, crosses the transportation joint, and as such has been cut and unidentified on ZF579. This wiring will be identified and re-connected, starting components will be examined and refurbished where necessary, in order to

1) Primarily establish that the engine control boxes are functioning correctly

2) Establish that HF and He ignition boxes are functioning correctly

Since neither engines nor starters are currently installed, the system will have to be ‘’tricked’’ to test HF and HE circuits, which can be done via manual manipulation of the Low and High-pressure switches.

12/08/04

Following circuits identified as incomplete, requiring identification and re-connection

1) No1 Starter over speed switch wiring. 2 cables cut at two conduit exits, require identification and re-connection. (Identification may be possible via multi-poles f83 and f84, spine section)

2) No1 low-pressure switch wiring. 3 cables cut at two conduit exits, port side nose.

require identification and re-connection via multi-poles f83 and f84, spine section.

KA22, KA23 and KA24

3) HF ignition wiring. 3 cables plus HT cable, cut at 2 conduit exits, nose. Identification via multi-poles f83 and f84 spine section. HT cable to be renewed

4) HE ignition wiring, 3 cables, low tension side. Cut at 2 conduit exits, nose.

Identification via multi-poles f83 and f84 spine section.

13/08/04

Starter over speed wiring, no1 LP switch and No1 He LT wiring identified via continuity from multi-poles f83 and f84, forward spine section. All wiring identified at two conduit exits, re- connected, shrink-wrapped and re-tagged.

Relays and contactors. Terminal screws removed and replaced with new items

ECU control boxes. Lids removed, internal components inspected, all contacts, micro switches and relays exercised manually, before power applied.

ECU control boxes MK3 Plessey connectors removed, cleaned and re-connected.

All starter circuit wiring and pins checked for correct connectivity and continuity, as per wiring blue prints.

14/08/04

All starter circuits’ condition established to be as per AP blue prints. Safe for power and test.

Stage 1: Engine Master selection and check relay functionality. PASS

Stage 2: speed switch disconnect. Volts test at pin A upon starter button press. PASS

Stage 3: re-connect. Voltage check at pump contactor connections. PASS

Stage 4: Re-connect pump contactor supply cable, check pump functionality. PASS

Stage 5: Connect LP switch, and check supply to pin D on control box.

Stage 6: No1 push button pressed, 28 Volt output from Pin D on controller. PASS

Stage 7: Function check with all circuits connected. Time switch function. PASS

Stage 8: Perform checks 1-7 for No2 starter circuit. PASS

Stages 1-8 have been performed for both No1 and No2 engine starter circuits, completing wiring and checks. No equipment requires replacement or further servicing at this point. Starter circuits now serviceable after 18 years dormant.

HF and HE circuits will be re-connected and checked next.

09/09/2007

No1 and n2 HE ignition circuits have now been reconnected, along with engine EGT, oil pressure, Tacho, and hydraulic warnings. All of these services run through the engine harness connectors shown below.