LANDING GEAR LIMIT (IAS) OPERATING EXTEND 270 .8M RETRACT 235K EXTENDED 320 .82K FLAPS LIMIT (IAS) UP OFF DN L A N D I N G G E A R RIGHT GEAR RIGHT GEAR LEFT GEAR LEFT GEAR NOSE GEAR NOSE GEAR LANDING GEAR LIMIT (IAS) OPERATING  EXTEND 270—.8M RETRACT 235K EXTENDED 320—.82K FLAPS LIMIT (IAS) Landing gear indicator (top) illuminated (red) Landing gear lever Landing gear limit speed placard  Override  trigger Landing gear indicator  (bottom) illuminated  (green)—related gear  down and locked Figure 13-43.  Landing gear selector panels with position indicator  lights. The Boeing 737 panel illuminates red lights above the green  lights when the gear is in transit. Figure 13-42.  Gear pin ground lock devices. Landing Gear System Maintenance The moving parts and dirty environment of the landing gear  make this an area of regular maintenance. Because of the  stresses and pressures acting on the landing gear, inspection,  servicing, and other maintenance becomes a continuous  process. The most important job in the maintenance of the  aircraft landing gear system is thorough accurate inspections.  To properly perform inspections, all surfaces should be  cleaned to ensure that no trouble spots are undetected. Periodically, it is necessary to inspect shock struts, trunnion  and brace assemblies and bearings, shimmy dampers, wheels,  wheel bearings, tires, and brakes. Landing gear position  indicators, lights, and warning horns must also be checked  for proper operation. During all inspections and visits to the  wheel wells, ensure all ground safety locks are installed.  of slippage marks, and proper inflation. Inspect landing gear  mechanism for condition, operation, and proper adjustment.  Lubricate the landing gear, including the nose wheel steering.  Check steering system cables for wear, broken strands,  alignment, and safetying. Inspect landing gear shock struts  for such conditions as cracks, corrosion, breaks, and security.  Where applicable, check brake clearances and wear. Other landing gear inspection items include checking  emergency control handles and systems for proper position  and condition. Inspect landing gear wheels for cleanliness,  corrosion, and cracks. Check wheel tie bolts for looseness.  Examine anti-skid wiring for deterioration. Check tires for wear, cuts, deterioration, presence of grease or oil, alignment  Various types of lubricant are required to lubricate points  of friction and wear on landing gear. Specific products to  be used are given by the manufacturer in the maintenance  manual. Lubrication may be accomplished by hand or with  13-25