Check for leaks in instrument cases, lines,
flexing. The panel is nonmagnetic and painted
and connections.
a dull black to eliminate glare and reflection.
Some panels are constructed in two layers,
and the instrument faces are flush with the
Check for dull or marred luminous paint
rear panel. The front panel is a reflector panel
on dial markings and pointers.
that mounts over the rear panel with sufficient
clearance to supply an indirect lighting effect. The
indirect lighting system is not standard for all
Check the condition of operation and
aircraft. Some aircraft have spotlights, edge
limitation markings. Also, check their
lighting, or a combination of these. Some
condition.
instruments have their own internal lighting
system.
C h e c k for contact and condition of
bonding on instruments.
Instrument panels are shock-mounted to
absorb low-frequency, high-amplitude shocks.
The mounts consist of square-plated absorbers in
Check shock mountings for condition of
sets of two, each secured to separate brackets.
rubber and security of attachment.
You should inspect the mounts periodically for
deterioration; if the rubber is cracked, replace the
Check for freedom of motion of all lines
pair.
and tubing behind the instrument panel.
Also, check that they are properly clamped
As an AE, your instrument maintenance
or taped to avoid chafing, and free from
duties include certain inspections that you
moisture, crimps, etc.
should conduct at regular intervals. During
a daily inspection, you inspect the following
Items:
After starting the engine, check the instrument
pointers for oscillation. Also, check the readings
Check pointers for excessive errors.
for consistency with engine requirements and
Some indicators should show existing
speeds. On multiengined aircraft, check the
atmospheric pressure, existing tempera-
instruments for the various engines against each
tures, etc. Others should indicate zero.
other. Investigate any inconsistency; it may
indicate a faulty engine, component, or instru-
ment.
Check instruments for loose or cracked
cover glasses. Replace pitot-static instru-
After you have diagnosed a particular trouble
ments if damaged.
and found the instrument to be faulty, remove
and turn it into supply. Remember, the following
Check instrument lights for proper opera-
precautions when removing and installing
tion.
instruments:
Check caging and setting knobs for
Handle instruments carefully at all times.
freedom of movement and correct opera-
Additional damage may result if you abuse
tion.
the instrument.
Carefully investigate any irregularity the
Do not change the location of an indi-
pilot reports.
ator.
When performing a phase/calendar inspec-
Do not force the mounting screws. If the
tion, make the following checks:
screw is cross-threaded, replace it. Do not
draw the screws up too tight against the panel.
This may distort the case enough to affect
Check the mounting of all the instru-
the operation of the instrument, crack the
ments and their dependent units for
case, or break off the mounting lugs.
security.
6-68
