Programming the shock cooling limit and cylinder, Programming the egt differential limit – Electronics International UBG-16 User Manual

Page 21

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Programming the Shock Cooling Limit and Cylinder:

Sudden cooling of the CHT (known as shock cooling) is a common problem in some engines. In others, it is rare.
Shock cooling an engine can result in bent pushrods due to exhaust valves sticking, burned valves, spark plug
fouling, broken piston rings, cracked cylinders at the spark plug and valve ports and warped exhaust valves.

A shock cooling limit may be set to alert when an engine’s CHTs are cooling too rapidly. In one Lycoming
document, it is recommended that the CHTs decrease no more than 20’F per minute. In another of its documents,
Lycoming recommends a decrease of no more than 40’F per minute.

You may want to start with a Shock Cooling Limit of 30’F per minute. When operating in the Normal Mode only

Normal Mode only

and displaying Shock Cooling ("SCOOL")

and displaying Shock Cooling ("SCOOL"), the Shock Cooling Limit may be set by performing the following
steps:

1. Press and hold the mode switch to the left until the word “PRO-
GRAM” appears in the digital display. Release the Mode Switch.
“SET” will appear on the left side of the UBG display. Also,
“S.COOL-XX” will appear in the left portion of the digital display
and the right portion will show the current Shock Cooling Limit
(“XX”). The digit to the far left will be blinking.

2. Use the Step Switch to increase or decrease the digit that is
blinking. The Shock Cooling Limit can be set from 0 to 99’F per
minute in 1’F increments.

3. Use the Mode Switch to blink a specific digit.

4. To set the cylinder to be monitored, push the Mode Switch to the right until the digital display shows
“S.C. CH X”. The right portion of the digital display will show the current cylinder (“X”) on which the
shock cooling rate is monitored. Use the Step Switch to change the cylinder number. You should monitor
one of the front, unobstructed cylinders.

5. To exit this programming mode, push and hold the Mode Switch to the left until the word “END” appears
in the digital display.

Note:

Note: Setting a limit to “000” will disable the limit and any alarms.

Programming the EGT Differential Limit:

It is recommended to set the EGT Differential Limit just outside the normal operating range for your engine so
problems can be detected without causing false warnings. False warnings are annoying and can desensitize you to
warnings in general. This could cause a serious delay in taking note of a warning which is an alert to a real
problem.

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