Card 1 — Front: Multi-Engine 28 Volt Turbine Electrical System (title)

Back: Trainer board showing how two turbine generators, battery, relays, regulators and buses interact; used for teaching. Sustained by the bench power or connected aircraft battery during demonstrations.

Card 2 — Front: Battery / Master (ON / OFF)

Back: Main power switch that connects the battery to the electrical system. Works like a main breaker; when ON it energizes buses and enables starters. Sustained by a charged battery and clean switch contacts.

Card 3 — Front: LH Starter-Generator

Back: Acts as starter motor during start then as generator once the engine runs. Mechanically driven by engine when generating; electrically driven from battery for starting. Sustained by engine drive, regular brush/armature maintenance.

Card 4 — Front: RH Starter-Generator

Back: Same as LH but for the right engine — provides redundant power and starting for that engine. Same sustainment: engine drive and routine maintenance.

Card 5 — Front: LH Starter Relay

Back: Heavy-duty solenoid that closes to feed high starter current to the LH starter. Energized by a start command. Sustained by correct control voltage and service/inspection of contacts.

Card 6 — Front: RH Starter Relay

Back: Same function for the RH starter; isolates starter current except during start. Sustained by proper coil voltage and contact condition.

Card 7 — Front: LH Shunt

Back: Low-value resistor that current flows through for measurement. Produces a small voltage proportional to heavy current for instruments/regulators. Passive and long-lived; protected by mounting and fuses.

Card 8 — Front: RH Shunt

Back: Same as LH shunt but on the right side; used for current sensing of RH generator outputs. Sustained by correct mounting and avoiding overload.

Card 9 — Front: Reverse-Current Diode (LH / RH)

Back: Prevents battery from discharging back into a non-producing generator. Allows current one way only. Sustained by proper rating and fuse protection; replace if shorted.

Card 10 — Front: Voltage Regulator (LH / RH)

Back: Senses bus voltage and adjusts generator field current to keep output ~28 V. Sustained by correct sensing wiring, healthy generator field parts, calibration checks.

Card 11 — Front: Over-Voltage Regulator / Cut-out

Back: Detects excessive generator voltage and either reduces excitation or disconnects generator to protect loads. Sustained by correct setting and service of relay contacts.

Card 12 — Front: Paralleling Rheostat

Back: Adjustable resistor used while paralleling generators to equalize load sharing. Operator trims it during synchronization. Sustained by careful adjustment and keeping windings intact.

Card 13 — Front: Paralleling Fuse

Back: Protects paralleling tie circuits from dangerous currents during generator tie-in. Blows on overcurrent. Sustained by replacing blown fuse with correct rating.

Card 14 — Front: Paralleling Bus / Battery-Starter Relay Buss

Back: Terminal strip/bus that distributes power to multiple circuits and relays. Keeps wiring neat and serviceable. Sustained by secure, corrosion-free terminals and proper torque.

Card 15 — Front: Radio Buss

Back: Dedicated power distribution for radios/avionics to allow isolation/protection. Sustained by fuses and clean terminals; prevents avionics loss if main bus issues occur.

Card 16 — Front: Diodes (group)

Back: Blocks reverse flow, combines sources, or rectifies. Used for isolation/ protection. Sustained by correct current rating and replacement if failed.

Card 17 — Front: Generator Drive Motor / Drive

Back: Represents the mechanical drive that turns a generator (engine gearbox in flight or motor on trainer). Sustained by mechanical coupling and its power source; bearings/mounts must be maintained.

Card 18 — Front: Inverter No. 2 / Inverter

Back: Converts DC (28 V) to AC for specific equipment. Electronic chopper/inverter circuitry requires steady DC input and cooling. Sustained by correct DC source, proper loading and cooling.

Card 19 — Front: RH Ignition (relay block)

Back: Relay(s) that supply ignition power to engine ignitors at start or relight. Sustained by control inputs and relay contact health.

Card 20 — Front: Wiring Harnesses & Labels

Back: Bundled white wires, clamps and labels keep the system organized and prevent chafing. Sustained by correct routing, secure tie points and labels.