MD Helicopters 369-500, Maintenance Instructions Manual

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CSP-HMI-3
MD Helicopters, Inc
.
MAINTENANCE MANUAL
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96-48-00
Page 201
Revision 11
The information disclosed herein is proprietary to MD Helicopters, Inc.
Neither this document nor any part hereof may be reproduced or transferred to
other documents or used or disclosed to others for manufacturing or any other
purpose except as specifically authorized in writing by MD Helicopters, Inc.
Copyright
©
1999 − 2016 by MD Helicopters, Inc.
FLOAT LAMP
MAINTENANCE PRACTICES
1. Float Lamp Description and Operation
(Ref. Figure 201) The float lamp assembly
provides a flood of light below and ahead of the
helicopter so the pilot can observe and assess
the suitability of a landing site without the aid
of ground-based lighting.
The assembly consists of two PAR 46, USASI
number 4580 lamps installed at Sta. 137.50,
relay K307 mounted on the inner side of the
front panel of the pilot's seat structure lower
section, FLT LDG LT circuit breaker switch
(CB140) installed in the lower right or lower
left corner of the instrument panel, and the
LDG LT FLOAT LT selector switch (S32)
which is mounted on the pilot's collective stick.
The lamps are rigidly installed in the stag­
gered array shown in Figure 201 and
Figure 203. The left lamp is depressed 20
degrees below horizontal; the right, 40 degrees
below. This arrangement provides an elliptical
light pattern for a forward landing approach
and for hovering.
Each lamp develops 400,000 candlepower at
450 watts, 28 Vdc. The approximate total
spread of each beam is 13 degrees horizontally
and 14 degrees vertically down to 40,000
candlepower, 10 percent of the maximum
candlepower. The average life expectancy of
the 4550 lamp is 10 hours.
The float lamp relay (K307) is mounted on the
rear of the front panel of the pilot's seat
structure lower section.
The float lamp switch is located on the pilot's
collective stick. Either the LDG LT or FLOAT
LT position can be selected. The contact rat­
ing is 5 amperes, resistive load, at 28Vdc.
The FLT LDG LT circuit breaker switch,
CB140, pushbutton reset type, is rated at 35
amperes. The circuit breaker switch may be
located in either the lower right or lower left
corner of the instrument panel.
2. Float Lamp Fault Isolation
Table 201 contains symptoms, probable causes,
measures required to determine causes of float
lamp failures, and recommended repairs.
Table 201. Float Lamp Assembly Troubleshooting
Symptom Probable Trouble Corrective Action
Float lamps fail to come on Master switch (S2) open Set master switch to ON.
FLOAT LDG LT circuit breaker open Press and reset FLOAT LDG LT circuit
breaker. If circuit breaker refuses to
remain set, inspect wires and
connections to relay K307. Refer to
Float Lamp Circuit Breaker Switch
Replacement.
FLOAT LDG LT circuit breaker
defective
Replace circuit breaker.
Lamps broken or burned out Replace lamps.
Defective LDG LT, FLOAT LT switch Replace switch.
Defective relay K307 Replace relay.
Loose wire L522H10 on 4, terminal
board TB101
Tighten wire connection.