DA20-C1 Flight Manual
Supplement 1
Doc # DA202-C1 April 16, 2009 Page S1 - 2
1. GENERAL
This supplement addresses the operating procedure for a DA20-C1 aircraft equipped with an
optional External Power Unit (EPU). The EPU receptacle and related circuits provide for the
connection of an external power source for various ground operations, e.g. maintenance,
battery charging, starting.
CAUTION
OVER-VOLTAGE PROTECTION DOES NOT EXIST. DO NOT
CONNECT ANY POWER SOURCE OTHER THAN 12 VOLT DC
BATTERY OR 14 VOLT (NOMINAL) DC GROUND POWER
CART.
The circuit provides protection in the event that the external power source is connected in
reverse polarity. A switch in the cockpit to the left of the light switches allows the EPU relay to
close once the external power source is connected and power is available. A light in the cockpit
indicates that power is available at the receptacle or that the EPU relay has remained closed
following a disconnect (see normal procedures).
On aircraft C0001 through C0148 and C0150 with an EPU installed, a relay bypass circuit is
provided to enable the battery relay to be closed if the battery has been discharged so much
that it does not have enough power to close the relay by itself. Depending on the state of
battery discharge, the battery relay may take several minutes to close. This circuit is not
installed on aircraft C0149 and C0151 onwards. See Figure 1.1 for location and Figure 1.2 for
simplified schematic. EPU plug Cole Hersee P/N 11042 is required to connect to the
receptacle. This receptacle is located in one of two locations. Aircraft serial numbers C0001
through C0148 and C0150 have this receptacle located on the fuselage at the rear portion of the
wing root. Aircraft serial numbers C0149 and C0151 onwards have this receptacle located on
the fuselage in front of the left-hand wing root.
Revision 24 DOT Approved
Figure 1.1
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