TM 5-6115-590-12
4-69. Ignition Unit
WARNING
Do not remove the igniter plug or ignition
unit unless they have been grounded.
The high-tension lead must be grounded
as soon as it is removed from the igniter
plug. Ground by touching the contact
spring in the lead to the igniter.
a.
Removal.
(1)
Remove wiring harness connector and
ignition lead assembly from ignition unit (fig. 4-41).
(2)
Remove four attaching bolts and washers
securing ignition unit to fire wall and remove unit.
b.
Cleaning and Inspection.
(1)
Clean ignition unit by wiping with a clean
rag moistened with an approved cleaning solvent.
(2)
Visually inspect ignition unit for cracks,
corrosion, damaged connector pins or other evidence of
damage.
c.
Test. Connect a satisfactory ignition lead
assembly and igniter plug to ignition unit. Connect a
28V DC power source to the ignition unit. The ignition
unit must cause the igniter plug to spark consistently at
a rate of 10 sparks per second, maximum.
d.
Installation.
(1)
Install a satisfactory or replacement
ignition unit in place on the fire wall and secure with
attaching washers and bolts.
(2)
Reconnect ignition lead assembly and
wiring harness connector to ignition unit.
4-70. Oil Pressure Sequencing Switch
a.
Removal.
(1)
Remove wiring harness connector and
tube assembly from oil pressure sequencing switch (fig.
4-41).
(2)
Remove attaching nut and washer from
clamp and remove oil pressure sequencing switch.
b.
Cleaning and Inspection.
(1)
Clean switch by wiping with a clean rag
moistened with an approved cleaning solvent.
(2)
Visually
inspect
switch
for
cracks,
corrosion, damaged threads or other evidence of
damage.
c.
Test.
(1)
Check switch actuation and closing and
check continuity across receptacle pins. Circuit across
pins A and B and across pins C and E should be open.
Circuit across pins C and D should be closed.
(2)
Install switch in a suitable holding device
and connect a source of filtered and regulated
compressed air to switch inlet port. Slowly apply air
pressure and check actuation of the switch. At 2.5 to
3.5 psig inlet air pressure, the switch should actuate
to close the circuits across pins A and B and across pins
C and E, and open the circuit across pins C and D.
NOTE
The closing of the circuit across pins A
and B and across pins C and E need not
be simultaneous providing the circuit
across pins A and B closes prior to the
circuit across pins C and E, and that both
circuits close within 2.5 to 3.5 psig inlet
air pressure.
(3)
Gradually decrease the inlet air pressure
and check switch deactuations. At 1.5 psig minimum
inlet pressure, the switch should deactuate to open the
circuits across pins A and B and C and E, and close the
circuit across pins C and D.
(4)
If switch does not actuate and deactuate
within specified limits, adjust switch as outlined in
paragraph d. below.
d.
Adjustment. Turn adjustment screw, located
adjacent to the electrical connector as required, to bring
switch actuation and deactuation within specified limits.
If switch cannot be properly adjusted, replace switch.
e.
Installation.
(1)
Install satisfactory or replacement oil
pressure sequencing switch in place on engine. Secure
clamp with attaching washer and nut. Tighten nut
securely.
(2)
Reconnect tube assembly using new
gasket and reconnect wiring harness connector to oil
pressure sequencing switch.
4-71. Time Totalizing Meter
a.
Removal.
(1)
Remove
four
attaching
screws
and
washers from engine bracket and remove time totalizing
meter bracket (fig. 4-41) from engine.
(2)
Remove wiring harness leads from meter.
Remove four attaching bolts and washers and remove
meter from bracket.
b.
Installation.
(1)
Install replacement time totalizing meter
on bracket and secure with attaching washers and bolts.
Tighten bolts securely.
(2)
Reconnect wiring harness leads.
(3)
Install meter and bracket in engine
bracket and secure with attaching washers and screws.
Tighten screws securely
4-72. Circuit Breaker
a.
Removal.
(1)
Remove
four
attaching
screws
and
washers from engine bracket and remove time totalizing
4-96
