Diamond DA 42 NG, Maintenance Manual

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AIRCRAFT
DA 42 NG AMM
Landing Gear
Doc # 7.02.15
Rev. 4
32-10-00
Page 1
15 Mar 2018
Section 32-10
Main Landing Gear
1. General
This Section tells you about the main landing gear. See the related Sections for data about these
systems that connect to the main gear:
)
Section 32-30. Extension and retraction.
)
Section 32-40. Wheels and brakes.
)
Section 32-60. Position and warning.
)
Section 57-00. Wing structure.
Refer to Chapter 92 for data about the electrical wiring of the landing gear systems.
2. Description
Figure 1 shows the main landing gear.
Each main landing gear is a tubular steel strut. The strut has a longitudinal pivot at the top. Large
bearings at each end of the longitudinal pivot hold the leg to the wing structure. A trailing arm attaches
to the bottom of the tubular steel strut. A gas/oil filled damper attaches to the rear of the tubular steel
strut and it attaches to the trailing arm.
The trailing arm carries an axle for the main-wheel assembly. Four bolts attach the axle to the trailing
arm. The axle has a steel plate that holds the brake unit. Clips and cable binders hold the hydraulic
hose for the brake unit and the electrical cables for the micro-switches to the leg.
Each main gear leg has a large hydraulic actuator to retract and extend the leg. One end of the
hydraulic actuator connects to the top of the tubular steel strut, near the longitudinal pivot. The other
end of the actuator connects to the wing structure via a folding stay.
3. Operation
Each main leg transmits vertical loads (for example, landing loads) to the airplane structure. When the
leg has a vertical load, the wheel pushes up the trailing arm. The trailing arm moves and compresses
the damper. The damper pushes up on the top of the tubular strut.
The damper can compress quickly but can only extend slowly. This prevents the leg from pushing the
airplane up after the landing and it also prevents vibration.