Cessna 17273274 Pilot Operating Handbook page 182

5
DIGITAL CLOCK
MODEL 172N
Once set correctly, the date advances automatically at midnight each
day until February 29 of each leap year, at which time one day must be
added manually.
Pressing the LH button two additional times will cause the time to
appear with the hours digits flashing. Using the RH button as before,
advance the hour digits to the correct hour as referenced to a known time
standard. Another push of the LH button will now cause the minutes digits
to flash. Advance the minutes digits to the next whole minute to be reached
by the time standard and "hold" the display by pressing the LH button once
more. At the exact instant the time standard reaches the value "held" by the
display, press the RH button to restart normal clock timing, which will
now be synchronized to the time standard.
In some instances, however, it may not be necessary to advance the
minutes digits of the clock; for example when changing time zones. In such
a case, do not advance the minutes digits while they are flashing. Instead,
press the LH button again, and the clock returns to the normal time
keeping mode without altering the minutes timing.
TIMER OPERATION
The completely independent 24-hour elapsed timer (see figure 3) is
operated as follows: press the center (MODE) push button until the timer
mode indicator appears. Reset the display to "zero" by pressing the LH
button. Begin timing an event by pressing the RH button. The timer will
begin counting in minutes and seconds and the colon (activity indicator)
will blink off for 1/ 10 second each second. When 59 minutes 59 seconds
have accumulated, the timer changes to count in hours and minutes up to a
maximum of 23 hours, 59 minutes. During the count in hours and minutes,
the colon blinks off for one second each ten seconds. To stop timing the
event, press the RH button once again and the time shown by the display is
"frozen". Successive pushes of the RH button will alternately restart the
count from the "held" total or stop the count at a new total. The hold status
of the timer can be recognized by lack of colon activity, either continuously
on or continuously off. The timer can be reset to "zero" at anytime using the
LH button.
There is no change to the airplane performance when the digital clock
is installed.
4
PILOT'S OPERATING HANDBOOK
SECTION 5
PERFORMANCE
SUPPLEMENT
1 July 1979