Q13-23. When does the compression stroke of a shock
On the drag brace shown in figure 13-12, a locking
strut begin?
mechanism is used where the lower and upper drag
braces meet. Usually in this type of installation, the
Q13-24. What part of the shock strut acts like a spring
locking mechanism is adjusted so that it is allowed to be
to return the strut to normal?
positioned slightly overcentered. You must be able to
Q13-25. What component of a landing gear system
inspect and adjust landing gear braces and locking
attaches the upper drag brace to the wheel
mechanisms as specified in the applicable MIM.
well?
To adjust the drag brace shown in figure 13-12, you
would first remove the cotter pin and nut (not shown)
LANDING GEAR SYSTEMS
from the lock arm shaft. With the drag brace in the full
MAINTENANCE
extended position, rotate the eccentric bushings that are
located on each end of the lock arm shaft.
LEARNING OBJECTIVE: Recognize the
procedures for drop checks, troubleshooting,
Both bushings must be rotated together to ensure
alignment, removal, and replacement of
that the high point of the eccentricity is the same on
landing gear systems and components.
both bushings. Failure to do this may result in damage
to the equipment or sluggish operation. The bushings
Mandatory drop checks are required for all
may be rotated in either direction until the end of the
landing gear maintenance procedures that involve the
lock arm shaft, shown as point "A" in figure 13-12, is a
removal and replacement of components, breaking of
distance of 0.003 inch to 0.015 inch from the striker.
hydraulic lines or fittings, and any adjustments to gear
This clearance is checked with a feeler gauge.
or door linkages. Conditional maintenance require-
ments cards call for a drop check whenever the aircraft
Other portions of the drag brace are nonadjustable,
experiences a "hard landing." In addition, regular drop
except for the length of its down lock cylinder. Figure
checks are required as part of the aircraft periodic
13-12 indicates the cylinder should be adjusted to a
inspection, even if there has been no reported
length of 12 3/8 inches.
discrepancy.
In the design of drag braces, the tendency has been
directed toward lessening the adjustment requirements.
DROP CHECK PROCEDURES
In some installations, drag braces are manufactured to
exact dimensions and do not require adjustments.
All drop check operations should be performed as
specified in the applicable maintenance instructions
Q13-15. What component is used to hold the doors of a
manual (MIM). These procedures should be thorough
landing gear system in the closed position?
enough to ensure that the system is free of leaks and the
Q13-16. What are the principal components of a latch
operational integrity of the system has been restored
mechanism?
following maintenance. Operational checks cover three
distinct areas. They are the operation of the landing
Q13-17. What component provides a main gear
gear and doors, the operation of the landing gear
up-and-locked indication on the pilot's
position indicator and warning system, and the
cockpit indicators?
operation of the landing gear emergency system.
Q13-18. What is the required clearance for a landing
The first step in the drop check procedures is to
gear door latch roller?
place the aircraft on jacks.
Q13-19 What determines the distance a landing gear
Further preparation includes connection of a
door will travel?
hydraulic test stand and external electrical power,
Q13-20. A shock struts uses hydraulic fluid and what
removal of landing gear maintenance safety locks, and
other substance to absorb and dissipate
the proper placement of the landing gear control
shock?
handle.
Q13-21. What chamber of a metering pin-type shock
As the operational procedure begins, check to make
strut contains the hydraulic fluid?
sure that the landing gear doors do not close in the path
of the retracting main struts. This condition will be
Q13-22. Where can you find information concerning
obvious (with hydraulic and electrical power on the
the correct type of hydraulic fluid to be used
aircraft) if the landing gear doors do not remain in the
in a shock strut?
13-11
