FG-03 Landing Gear and Electrical Systems

Landing gear system

• Conventional, Tricycle, Dual Wheel.

• Retraction/Extension from No.2 Hydraulic System

• Main Landing Gear equipped with Disc Brakes & Anti-skid System.

• Nose wheel is fully steerable

Landing gear safety mechanisms

- Proximity Switch Electronics Unit (PSEU)

- Ground Lock Pins (Main Landing Gear)

- Nose Gear Ground Lock Mechanism

- MLG Door and Nose Gear Door Pins

Main landing gear lock pins

Installed if high visibility orange tape is visible

NEVER enter the engine nacelle if this pin is not in place.

Nose gear ground lock

When Pulled out and turned, a cable operated mechanism locks the nose gear drag strut in the down lock position.

Landing gear extension and retraction

Hydraulic actuators operate MLG and NLG and Landing Gear Doors (except NLG aft doors, operation is mechanically linked with nose gear extension and retraction).

Mechanical up locks and down locks are hydraulically actuated to secure gear and doors.

What does PSEU monitor?

Position of up locks & down locks, gear doors, gear legs and strut compression.

Sends inputs to various Landing Gear System advisory Lights

Alternate gear extension systems

Manual PTU (Power Transfer Unit) Selection

Emergency Hand-Operated System

Manual PTU Selection

A pump failure or a No.2 engine failure but the hydraulic system was otherwise still intact. Provides No.1 hydraulic power to the No. 2 system.

Emergency hand-operated system

Completely independent hydraulic system for Main Landing Gear. Used if No.2 Hydraulic System cannot hold pressure (fluid loss)

What does emergency hand operated system consist of?

Reservoir (1.2L)

Hand pump (handle is stowed behind copilot)

Emergency Selector Valve

Emergency hand operated system operation

1. Open the access panel on the floor by the co-pilot. This will automatically activate the emergency selector valve.

2. Insert handle into pump socket.

3. Open the overhead Alternate Release Door and pull Main Landing Gear Release Handle. There are two detents. Pulling to the first detent releases door up-lock and pulling to the second releases the gear up-locks. It should be pulled as far as it will go. The landing Gear will free fall to the partially extended position.

4. When the pump is stroked it will fully extend and lock the MLG.

5. Pull the Nose Gear Release handle in the access panel to free fall the nose gear to the fully extended and locked position. The slip stream and gravity is sufficient for the Nose Gear to extend and lock.

6. Down lock verification lights will illuminate when gear is down and locked, with the down lock verification switch selected ON.

Two power systems on board

DC power

AC power

DC Power voltage

28V

DC power sources

2 Starter-Generators

2 Transformer Rectifier Units (TRU)

2 Batteries (24 V)

External Power Receptacle

DC Starter generators

- Mounted on accessory gear box of each engine.

- Starter motor reverts to generator after engine start.

- Regulated 28 V DC output regardless of changes in speed or load.

TRUs

- 2 installed in nose section.

- Receives 115 V, 3 phase AC power and converts it to 28 V DC.

- Ensures DC power is available even if both Starter-Generators fail.

Main and auxiliary battery

- 24 V sealed lead acid battery (SLAB)

- located in the nose compartment.

- Main Battery charged by APU AC generator or when ac external power is applied.

DC external power system

Receptacle on left side of nose

Allows connection to a DC ground power unit.

2 AC Power types

115V 3 phase variable frequency (333 to 528 Hz)

115V 3 phase 400Hz (fixed frequency)

Variable frequency AC power uses

Propeller de-icing, auxiliary fuel pumps, stand-by hydraulic pumps, windshield heat, and stall warning transducer heaters

Fixed frequency AC power uses

Instruments, navigation, and communications equipment

AC Power sources

- AC Generators

- Inverters

- Auxiliary Power Unit (APU)

- External AC power

AC generator

- Mounted on propeller gearbox of each engine.

- Operate when engines running and props are un-feathered

- provides 115 V, 3-phase, variable frequency AC power

Inverters

- 9 Solid state static inverters.

- 3 in flight compartment (Avionics)

- 3 under floor in cabin (NTS)

- 3 in nose compartment (Search Radar)

- Receive 28 V Dc and converts to 115 V, 3-phase, 400 Hz power

AC external power

- Ext. Power Receptacle in the inboard side of the right nacelle.

- Allows operation of variable frequency AC system from a ground power source.

Circuit protection

- 4 CB Panels in Flight Compartment.

- NTS CB Panel on the NTS Computer Rack and above each NTS Console.

- 6 Remote Control Circuit Breakers (RCCB’s) for the Radar.

Where is the APU AC generator installed?

In the rear of the cargo area in the aft fuselage

APU functions

to supply air conditioning and basic electrical power on the ground. It cannot be used to start the engines.

What power does APU generator provide?

115V 3 phase 400Hz AC