S 212-004
(2)
Examine the trailing edge flap jackscrews, actuating linkages and rods for damage and blockage due to pieces of the tire.
S 212-006
(3)
Examine the landing gear wheel well areas for damage and obstruction from pieces of the tire.
NOTE: Carefully examine the hydraulic plunbing, flap torque
____ tubes, and control cables and mechanisims for damage or distortion.
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A 747-400 MAINTENANCE MANUAL
(4) S 212-007Examine the landing gear assemblies, related components and hydraulic lines for damage and/or hydraulic fluid leakage.
(5) S 212-008Examine the wheel well doors and wheel well door actuating rods for damage and/or blockage from pieces of the tire.
(6) S 212-009Examine the other tires for possible damage (Ref 32-45-04/601).
NOTE:____ Carefully inspect the other tires for slash and/or wire penatration damage of the tread or the sidewall.
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A
747-400 MAINTENANCE MANUAL
VOLCANIC ASH CONDITION - MAINTENANCE PRACTICES
______________________________________________ (CONDITIONAL INSPECTION)
________________________
TASK 05-51-35-202-001
1. Volcanic Ash Conditional Inspection___________________________________
A. General
(1)
Flight crew reports of electrostatic discharge across the windshields are indications of a volcanic ash condition. Other indications are a bright light produced by a heated material in the engine inlets, and a subsequent engine shutdown. Also, a possible decreased view through the windshields and windows can occur.
(2)
Volcanic ash is a very abrasive material that is usually found to be noncorrosive. But, because volcanic ash is very abrasive, finished surfaces open to volcanic ash can become corroded.
(3)
The texture is almost the same as talcum powder. The dimensions of most ash particles are less than 5 microns with trace quanities that are more than 50 microns. Volcanic ash is very abrasive. Be careful when you wash the airplane because you can cause damage to the airplane if you rub the surface too hard.
(4)
Volcanic ash will stay on bare lubricated surfaces. It can go into many conventional seals, go into the engine gas path or go into the air condition system. It is possible for the ash to go into other openings on the airplane. Bare lubricated surfaces that are known to be contaminated with volcanic ash must be cleaned and relubricated . Do this as soon as it is possible to prevent unusual worn areas to the parts that move. Some of these parts are the inner cylinders of the landing gear shock strut, and hydraulic actuator rods. Also there are stabilizer trim and flap screw mechanisms. You must monitor parts that turn or slide for signs of volcanic ash related damage. This procedure must be done as a program that follows if initial damage was not found.
(5)
Volcanic ash incidents that have occured to engines have shown that the ash will change conditions. As the ash goes through the combustor, it will change to between a plastic flow and molten condition. In this condition, it will have very high adhesive qualities and properties. The ash will bond to the nozzle guide vanes of the high pressure turbine. It will also bond to the rotor blades of the high pressure turbine. When the ash bonds to these components, it will cause a decrease in the turbine flow area. It also will cause a decrease of nozzle guide vane and turbine blade cooling air.
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