TM 55-4920-231-14
PART NO.
INSTRUMENT
their removal from the tester, in a manner simi-
lar to that used in testing a remote instrument.
Manifold Pressure Gage
AN 5770-5
(MS 28077-5)
Refer to the applicable technical manual for the
MS 28061-1
Fuel Pressure Gage
particular instrument for range of accuracy in
calibrating.
97. OIL RESERVOIR.
b. Repair. Accomplish repair of instruments
Remove, disassemble, clean, and inspect the
in accordance with the applicable technical man-
reservoir assembly as outlined in paragraph 77.
Repair of the reservoir consists primarily of the
uals for the part numbers as listed below.
replacement of defective parts as a consequence
INSTRUMENT
PART NO.
of inspection and observance of function. Reas-
MS 28049
Rate-of-climb Indicator
semble and install the reservoir as outlined in
Altimeter
MS 28044-1
Airspeed Indicator
MS 28021-1
Section V. ELECTRICAL SYSTEM
(2) Unsolder wiring harness (4, figure 25)
leads from terminals on transformer (46).
Remove electrolytic filter capacitor (2, figure
(3) Remove nuts (21), lockwashers (22),
24) from chassis (20) for replacement as fol-
and screws (35), securing transformer (46) to
lows:
chassis (51), and remove transformer.
a. Removal.
c. Installation.
(1) Remove chassis assembly (figure 24)
from tester case (paragraph 73a).
(1) Place transformer (46, figure 25) in po-
sition on chassis (51) and secure with screws
(2) Unsolder wiring harness (4, figure 25)
leads from terminals on capacitor (43).
(35), lockwashers (22), and nuts (21).
(3) Remove nuts (39), terminal (40), and
(2) Solder wiring harness (4) leads to ter-
minals on transformer (46) as indicated in fig-
screws (41 ) securing bracket (44) and ground
leads to chassis (51).
ure 10.
(3) Install chassis assembly (figure 24) in
(4) Remove capacitor and bracket assembly
(42).
tester case (paragraph 73c).
d. Test.
b. Installation.
(1) Insert a Variac or an equivalent varia-
(1) Place capacitor and bracket assembly
ble transformer in the primary circuit of the
(42, figure 25) in position on chassis (51), in-
transformer and set the input at 115 volts.
sert screws (41), install ground leads and termi-
(2) Provide a test setup having a load suf-
nal (40), and secure with nuts (39).
ficient to cause a 2.2 ampere flow of current in
(2) Solder leads to terminals on capacitor
the secondary circuit.
(43) as identified, or refer to figure 10.
(3) Check the voltage across the secondary
(3) Install chassis assembly (figure 24) in
output. It should be approximately 26 volts.
tester case (paragraph 73c).
99. TRANSFORMER.
Remove, clean, and inspect motor and pump
The stepdown transformer (6, figure 24) is
assembly as directed in paragraph 81 and, using
inspected, replaced, and tested as follows:
a. Inspection.
perform the procedures which follow:
(1) Inspect transformer for signs of exces-
a. Inspection. At disassembly, inspect
sive heat such as melted solder or wax, burned
insulation, and odor of burned materials.
motor and pump assembly as follows:
(2) Check terminal to see that connections
(1) Check resistance between motor input
are tight.
leads and ground. Reading should be approxi-
(3) Check leads for shorted or bare wires.
mately 1.7 ohms.
(2) Check field windings for continuity,
b. Removal. If it is necessary to replace the
transformer, proceed as follows:
grounds, and shorts.
(1) Remove chassis assembly (figure 24)
(3) Examine bearings for excessive wear
from tester case (paragraph 73a).
and other defects.
