Overview
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Replace with overview of 5-gear configuration, retraction/extension, steering, and braking.
The 747-400 has five landing gear assemblies: a nose gear (2 wheels), two wing gear (4 wheels each), and two body gear (4 wheels each) — total 18 wheels. All gear retract hydraulically (Sys 1 for body and nose, Sys 4 for wing gear, with crossovers). Alternate extension uses gravity drop with hydraulic isolation.
Architecture
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Insert
<LandingGearSchematic /> once built.Components
| Nose Gear | 2 wheels, steerable (±70° tiller, ±7° rudder pedals) |
| Wing Gear | 2 × 4-wheel bogeys (outboard, under wings) |
| Body Gear | 2 × 4-wheel bogeys (inboard, on fuselage) |
| Body Gear Steering | Active above 20 kts during turn — assists tight turns |
| Normal Brakes | Sys 4 |
| Alternate Brakes | Sys 1 |
| Anti-skid | All 16 main wheels, dual-channel |
| Autobrake | RTO, 1, 2, 3, 4, MAX |
| Tire Speed Limit | 235 KGS |
Normal Extension/Retraction
- Up: Lever UP — hydraulic retraction, ~14 sec all gear up & locked
- Down: Lever DOWN — hydraulic extension, ~14 sec all gear down & locked
Alternate Extension
- Landing gear lever — OFF (electrically powered position)
- Alternate gear extend handle — OPEN
- Gear free-falls, locked by aerodynamic + gravity loads
Failures & Abnormals
CAUTION — Gear Disagree
Cycle the lever once. If still disagree, plan for alternate extension; review QRH for landing technique on partial-gear configurations.
Limits
- Gear Operating (VLO): 270 KIAS (extend), 270 KIAS (retract)
- Gear Extended (VLE): 320 KIAS / M 0.82
- Tire speed: 235 KGS
Notes / Personal
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User notes.