(a)
A Light Glossy Brown Film
(b)
A Dull Black Carbonaceous Residue
(c)
A Bared Surface
(3)
Deterioration of titanium parts will show as a bright etched surface.
B. Standard Tools and Equipment
(1) Scrapers - Wooden or Plastic
C. Consumable Materials
(1) B00340 Alcohol - Isopropyl
D. References
(1) 36-11-01/401, Pneumatic Manifold
E. Examine Titanium Parts.
NOTE: Titanium parts in hydraulic fluid areas are protected by
____ an inorganic flat black or gold finish, and/or with a shield.
Do not confuse the black finish with the carbonaceous residue.
S 112-002
(1)
Clean the hydraulic fluid film/residue from the titanium parts with isopropyl acohol and a scraper.
S 212-003
(2)
Examine all of the titanium parts in these areas for contamination and/or deterioration:
(a) Landing Gear Wheel Wells
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747-400 MAINTENANCE MANUAL
(b)
Engine Firewalls
(c)
Apu Firewall
(d)
Wing-to-Body Fairings Under the Wing
(e)
Fuselage Area Between the Pressure Bulkhead and the APU Firewall
(f)
Strut Attach Linkages
(g)
Spars
S 682-004
(3) Replace the parts which show paint deterioration or metal etching (Ref 36-11-01/401).
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747-400 MAINTENANCE MANUAL
LIGHTNING STRIKE CONDITION (CONDITIONAL INSPECTION) - MAINTENANCE PRACTICES
___________________________________________________________________________
1. General_______
A. This procedure has these three tasks:
(1)
Examine the External Surfaces for Lightning Strike
(2)
Examine the Internal Components for Lightning Strike
(3)
Inspection and Operational Check of the Radio and Navigation Systems
B. The airplane has all the necessary and known lightning strike protection measures. Most of the external parts of the airplane are metal structure with sufficient thickness to be resistant to a lightning strike. This metal assembly is its basic protection. The thickness of the metal surface is sufficient to protect the internal spaces from a lightning strike. The metal skin also gives protection from the entrance of electromagnetic energy into the electrical wires of the aircraft. The metal skin does not prevent all electromagnetic energy from going into the electrical wiring; however, it does keep the energy to a satisfactory level. If lightning strike strikes the airplane, you must fully examine all of the airplane to find the areas of the lightning strike entrance and exit points. When you look at the areas of entrance and exit, examine this structure carefully to find all of the damage that has occurred.
C. Lightning strike entrance and exit points are usually found in Zone 1 (Fig. 201), but can also occur in Zone 2 and 3.
D. You can usually find signs of a lightning strike in Zone 1 (Fig. 201). However, lightning strikes can occur to any part of the airplane which includes the fuselage, wing skin trailing edge panels, wing-body fairing, antennas, vertical stabilizer, horizontal stabilizer, and along the wing trailing edge in Zone 2 (Fig. 201).
E. In metal structures, lightning damage usually shows as pits, burn marks or small circular holes. These holes can be grouped in one location or divided around a large area. Burnt or discolored skin also shows lightning strike damage.
F. In composite (non-metallic) structures, solid laminate or honeycomb damage shows as discolored paint. It also shows as burned, punctured, or delaminated skin plies. Damage you cannot see can also be there. This damage can extend around the area you can see. Signs of arcing and burning can also occur around the attachments to the supporting structure.
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