Retraction tests should be carried out following replacement of a faulty component, whenever incorrect operation is reported or suspected, and after a hard or over weight landing. The sequence of operation will depend on the particular installation and type of retraction system concerned, and full details should be obtained from the relevant Maintenance Manual. The following procedure is applicable to most retraction landing gears.

• Raise the aircraft so that the wheels are clear of the ground, and lock lifting Jacks. Ensure that no ground equipment or personnel are in the vicinity of the undercarriages and doors.
• Configure aircraft for proper operation and pulling necessary CB’s or the software’s should be reset.
• Connect electrical power and external hydraulic or pneumatic servicing equipment as appropriate.
• Carry out several retractions and extensions, initially at low power to ensure slow operation, and using both the normal and emergency systems.

Fixed-Gear Inspection.

Fixed landing gear should be examined regularly for wear, deterioration, corrosion, alignment and other factors which may cause failure or unsatisfactory operation. During 100 hour period or annual inspection of fixed gear, the airplane should be jacked up so the gear does not bear the weight of the aircraft. The mechanic should then attempt to move the gear struts and wheels to test for play in the mounting. If any looseness is found, the cause should be determined and corrected.

When landing gear which employs rubber shock(bungee) cord for shock absorption is inspected, the shock chord should be inspected for age, fraying of the braided sheath, narrowing (necking) of the cord and wear at points of contact with the structure. If the age of the shock cord near five years or more, it is advisable to replace it with new cord, regardless of other factors. Cord which shows other defects should be replaced, regardless of age.

Shock absorber of the spring-oleo type should be examined for leakage, smoothness of operation, looseness between the moving parts, and play at the attaching points. The extension of the strut should be checked to make sure that the springs are not worn or broken. The piston section of the strut must be free of nicks, cuts and corrosion.