TASK 53-11-37-600-805
5. Main Gear Wheel Well and Keel Beam - Corrosion Prevention
Figure 204
A. General
(1) The main gear wheel well is in the fuselage section aft of the bulkhead at the rear spar of the
wing center section. The floor is formed by the wing to body fairing with an opening provided to
fit the tire, with the outboard tire providing the closure for the cavity. A keel beam carries the
longitudinal stress loads across the cavity. The wheel well in the fuselage extends into the
inboard end of the wing trailing edge structure. The wing wheel well houses the greater portion
of the landing gear components.
(2) The surfaces inside the fuselage are exposed to air contaminants and runway splash and are
subject to corrosion.
(3) The wing wheel well should be treated at the same time as the trunnion attach fittings, the
landing gear support beam and forward trunnion support structure.
(4) Stress corrosion cracking has been reported in the horizontal integral ribs of the BS 685 and
706 frames. Cracks occurred at WL192, 202 and 208 on Sta 685 frames and at WL202 on STA
706 frames on both sides of airplanes. Cracks originated at, or passed through holes for
fasteners used to attach shear webs to frame ribs. Cracks occurred in frames made from 7079
material.
(5) Stress corrosion cracks have occurred in the keel beam left and right lower tee chord. They
initiated under the splice near the ends of the 7178-T6511 aluminum chords at Sta 743.
Corrosion has also occurred between the tee chord and skin.
(6) Corrosion has been reported on the keel beam lower chord surfaces between STA 520 and
STA 540 and aft of STA 727. Stress corrosion cracks have also been reported on the keel
beam lower chord at STA 590 and between STA 530 and STA 536.
(7) Stress corrosion cracking has been reported in the horizontal flange of the forward and aft
frame fitting at STA 695. The cracks ran along the line of fasteners common to the stringer
S-18A shear beam Figure 204 (Sheet 2).
(8) Stress corrosion cracks has been reported in both left and right inboard splice tees of the keel
beam at the main wheel well aft bulkhead Figure 204 (Sheet 3).
(9) Refer to CORROSION PREVENTION, SECTION 51-00 of this manual for a discussion of the
Aging Airplane Corrosion Prevention and Control Program and related documentation.
Structural items within this section are subject to the unique requirements of the mandatory
Corrosion Prevention and Control Program.
B. References
Reference Title
29 HYDRAULIC POWER
51-00 CORROSION PREVENTION
51-00-51 INSPECTION AND DETECTION
51-00-59 STANDARD PREVENTIVE MAINTENANCE PROCEDURES
C. Consumable Materials
Reference Description Specification
G00009 Compound - Organic Corrosion Inhibiting BMS3-23
737-600/700/800/900
AIRCRAFT MAINTENANCE MANUAL
53-11-37
Page 220
D633A101-ILF Jun 15/2015
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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