Cessna Aircraft Company P.O. Box 7706, Wichita, Kansas 67277, USA (316) 517-5800 Facsimile (316) 942-9006
COPYRIGHT © 2008
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Cessna Aircraft Company cannot be responsible for the quality of work performed by others while fulfilling the
requirements of this Service Letter. Procedures specified in this Service Letter must be accomplished using industry
standard maintenance practices and applicable government regulations.
Page 6 of 6
Figure 4
CO GUARDIAN CARBON MONOXIDE DETECTOR
The Model 452-201 Series Carbon Monoxide Detector is designed to detect, measure,
and provide a visual and aural alert to the pilot before the level of carbon monoxide
(CO) reaches a critical level.
The installation consists of a single carbon monoxide detector installed behind the
instrument panel that activates a red annunciator and an aural warning. The aircraft
supplied power and aircraft wiring is protected by a 2 amp circuit breaker. There is a
test/reset button located on the left hand side of the engine instruments panel between
the fuel quantity indicator and manifold pressure/fuel flow gauge. A red light is
located on the annunciator panel.
The carbon monoxide alarm level is calibrated to alert the pilot within five minutes or
less whenever the carbon monoxide level reaches 50 parts per million (PPM) by
volume or above. The warning time is shortened at higher levels of CO
concentrations and becomes approximately instant should the CO level reach 400
parts per million by volume (PPM) or above.
In case of a CO alert, the red annunciator will illuminate continuously and the aural
warning will state “Carbon Monoxide” every two seconds. The visual alert will
remain until the CO level is again reduced below the alert level. The aural warning
may be silenced by pressing the ACK button on the annunciator panel. The indicator
is automatically reset when the CO level drops below 50 PPM.
On initial power up, the detector goes through a self-test and the annunciator light
flashes twice, but the aural warning will remain off. There will be a three minute
warm-up time before the detector is operational. To test the system any time, press
and release the test/reset switch. As on initial power up, the detector goes through a
self-test and the annunciator light will flash twice, but the aural warning will remain
off. To reset the system, press the test/reset switch and assure that the annunciator
light flashes twice. If the detector sensor fails, the annunciator light will flash every 4
seconds, but the aural warning will not sound.
