I. INTRODUCTION
This manual provides information for installing the P/N 2044-1
Volt & Vac Alert Warning System on a general aviation aircraft.
All installation work is to be performed in accordance with this
manual and applicable sections of AC 43.13 - 1B.
II. BASIC OPERATIONS
The Volt & Vac Alert System is an electronic device which
provides the pilot of the aircraft with an instant warning for
both low electrical voltage, and low instrument vacuum or
pressure. If the aircraft electrical voltage or the instrument
vacuum or pressure fall below a set value, the pilot will hear
an instantly recognizable voice warning directly in his head
set, and will see a red light on the instrument panel as an
indication of the problem. Separate voice messages are used to
distinguish the type of failure. The system consists of two
subassemblies, an electronic module, which is mounted inside the
aircraft, and a red indicator light, which mounts on the
instrument panel, close to the gyro instruments, and a switch to
allow turning off the system. The system functions as follows:
Any time the aircraft voltage falls below a set value, the pilot
will hear the voice message “CHECK VOLTAGE, CHECK VOLTAGE” once
in his headset. The panel-mounted red light will then
illuminate, providing a visual indication of the problem. The
light will continue to stay on until the voltage is again above
the set value.
Note: A delay has been added to the voltage warning requiring
that the aircraft voltage be below 12v or 24v continuously for 1
minute before the warning will sound.
If the instrument vacuum or pressure falls below a set value,
the pilot will hear the voice message “CHECK GYROS, CHECK GYROS”
once in his headset. The panel-mounted red light will illuminate
until the instrument vacuum or pressure is again above the set
point.
NOTE: THE VOLT & VAC ALERT IS AN ADVISORY SYSTEM ONLY. IT
SHOULD NOT BE UTILIZED AS THE PRIMARY MEANS OF DETERMINING LOW
VOLTAGE, LOW VACUUM, OR LOW PRESSURE. THE PILOT SHOULD CONTINUE
TO UTILIZE THE NORMAL OPERATING PROCEDURES, CHECKLISTS, LIGHTS,
INDICATORS, ETC. AS DEFINED IN THE AIRCRAFT FLIGHT MANUAL AS THE
PRIMARY INDICATION OF PROPER OPERATION.
III APPLICABILITY
Refer to the Approved Model List (AML), Specification 2044AML
Rev 0, or later FAA approved revision for a listing of the
aircraft models approved for installation of the P/N 2044-1 Volt
& Vac Alert System
IV. INSTALLATION INFORMATION
A. Mechanical Installation
1. Locate a place in the aircraft to mount the P/N 2044-2
electronic module. The unit can be mounted to the aircraft
structure, side panels etc. Pick a location where the pressure
signal tube or tubes can be conveniently connected to the
instrument system.
2. Drill 2 mounting holes as shown on Fig A, and mount the unit
using the hardware provided.
3. Determine a location on the instrument panel for the warning
light. The light should be located close to the gyro
instruments, within the pilot’s normal scan of these
instruments. Verify that there is sufficient space to place the
label for the light. An on/off switch should be mounted in the
panel in a convenient location by the gyro instruments.
4. Drill a 5/16 dia. hole through the panel, install the label,
and the light.
5. Mount an on/off switch in a convenient location that is
accessible to the pilot in flight. Label the switch “Volt & Vac
on/off.”. The switch should be an aircraft quality SPDT toggle
or rocker switch rated 1 amp at 28v minimum, such as AN3021-2 or
equal.
B. Electrical Installation
1. Refer to Fig 1, 2, or 3 for information on the electrical
installation. The Volt & Vac alert system is compatible with
both 12v DC and 24v DC electrical systems. Refer to Note1 for
information on the correct wire color for the aircraft voltage.
Hook either the red wire (for 12-volt systems) or the green wire
(for 24-volt systems) to the aircraft buss through a 1 amp fuse
or circuit breaker and the on/off switch.
2. Attach the BLACK wire to a good aircraft ground.
3. Attach the BLUE and ORANGE wires to the same color wires on
the light.
4.The Volt & Vac incorporates a standard 600 ohm audio output.
The audio output must be hooked into the aircraft audio system
in a way that the pilot cannot accidentally turn it off. If the
aircraft has an audio panel that incorporates an un-switched
audio input, the Volt & Vac audio output should be hooked to
this point. This will provide a voice warning directly into the
pilot’s headset and through the cabin speaker. Hook the WHITE
wire to this un-switched audio input. If the aircraft does not
have an audio panel with an un-switched input, then the WHITE
wire can be hooked directly to the pilot’s headset jack located
on the instrument panel
5. Cut any remaining wires and insulate the ends. Secure all
wiring in place.
C. Hookup to Aircraft Instrument System
Aircraft gyro systems can be configured in 3 different ways. The
most common configuration uses a vacuum source referenced to the
cabin air pressure to power the instruments. Some pressurized
aircraft reference the vacuum source to the air pressure outside
the aircraft pressure boundary. Other aircraft use a pressure
system referenced to the cabin air pressure to power the
instruments. The installer must determine which of these
configurations exist in the aircraft, and then refer to the
proper Fig (1, 2, or 3) and installation section.
1. Aircraft with vacuum systems referenced
to cabin air pressure
a) The P/N 2044-1 electronic module has 2 plastic tubes exiting
the case. One tube marked with a RED band close to the case is
the HIGH pressure connection. The other unmarked tube is the LOW
pressure connection.
b) Attach the LOW pressure tube to the aircraft vacuum system.
Install the P/N 2044-7 adapter into the aircraft vacuum system
as shown on Fig 1. It can be installed into a section of tubing
attached to an unused port on an instrument, or it can “T” into
an existing vacuum line. The adapter can be used with 1/4 ID,
3/8 ID, or ½ ID tubing. Install the adapter into the line, and
secure with a clamp. Cut the LOW pressure tube to length, and
install it on the other end of the adapter. Secure with a clamp
or safety wire. Secure the LOW pressure tube in place. Do not
bend the tube in a radius smaller than 1 inch. Use care not to
crush the tube when securing. Refer to AC43.13-1B section 9 for
details on running and securing tubing.
c) Cut off the HIGH pressure tube close to the electronic
module.
2. Aircraft with vacuum systems referenced to air pressure
outside the aircraft pressure boundary (pressurized aircraft).
a) The P/N 2044-1 electronic module has 2 plastic tubes exiting
the case. One tube marked with a RED band close to the case is
the HIGH pressure connection. The other unmarked tube is the LOW
pressure connection.
b) Attach the HIGH pressure tube to the air inlet side of the
gyro instruments. Attach the LOW pressure tube to the vacuum
side of the gyro instruments. Install a P/N 2044-7 adapter into
the aircraft vacuum and air inlet systems as shown on Fig 2. The
adapters can be attached into unused ports on the instruments,
or they can “T” into existing vacuum lines. The adapters can be
used with ¼ ID, 3/8 ID, or ½ ID tubing. Install the adapters
into the lines and secure with clamps. Cut the plastic tubes to
length and install them on the other end of the adapters. Secure
the tubing to the adapters with a clamp or safety wire. Secure
the plastic tubes in place. Do not bend the tubes in a radius
smaller than 1 inch. Use care not to crush the tubes when
securing. Refer to AC 43.13-1B section 9 for details on running
and securing tubing.
3. Aircraft using pressure systems to power the gyro
instruments
a) The P/N 2044-1 electronic module has 2
plastic tubes exiting the case. One tube marked with a RED band
close to the case is the HIGH pressure connection. The other
unmarked tube is the LOW pressure connection.
b) Attach the HIGH pressure tube to the pressurized side of the
gyro instruments. Install a P/N 2044-7 adapter into the aircraft
pressure system as shown on Fig 3. The adapter can be attached
to an unused port on the instruments, or it can “T” into the
existing pressure tubing. The adapter can be used with ¼ ID, 3/8
ID, or ½ ID tubing. Secure with a clamp. Cut the HIGH pressure
tube to length and install on the other end of the adapter.
Secure with a clamp or safety wire. Do not bend the tube in a
radius smaller than 1 inch. Use care not to crush the tube when
securing. Refer to AC 43.13-1B section 9 for details on running
and securing tubing.
c) Cut off the LOW pressure tube close to the case.
V. SYSTEM CHECKOUT AND OPERATION
1. Turn on the master switch and the on/off switch. Since the
system voltage and the instrument vacuum or pressure are both
below the set points, both warning messages will be heard in the
pilot’s headset. The voice messages will play only once. The RED
warning light on the panel will then illuminate continuously.
This acts as a test of the system. Verify that the voice volume
is adequate. If either warning message fails to sound, this
constitutes a failure of the test and it will be necessary to
determine the cause of the problem.
Note: There will be a 1 minute delay after the master switch is
activated before the voice sounds
2. Verify that the RED warning light illuminates after the voice
messages, and that the brightness is adequate. If the light does
not illuminate, or it is not bright enough to be seen under
normal conditions, that constitutes failure of the test. It will
be necessary to replace the unit.
3. Start the engine. Verify that the aircraft generator or
alternator is charging (system voltage should be greater than
12v or 24v). Verify that the instrument vacuum or pressure is
greater than 1 inch HG or 0.5 psi. The RED warning light should
turn off. If the light continues to illuminate when the voltage
and vacuum or pressure are above the set values, that
constitutes a failure of the test. Verify that the signal lines
are not being pinched closed. If this does not correct the
problem, it will be necessary to replace the unit.
4. Decrease the engine rpm to idle. The instrument vacuum or
pressure will decrease. As the vacuum or pressure falls, the
voice message “CHECK GYROS, CHECK GYROS” should be heard in the
pilot’s headset. The RED warning light should illuminate.
Increase the engine rpm again until the vacuum or pressure is
above 1 in HG or 0.5 psi. The warning light should turn off. If
the system fails to follow this sequence, that constitutes
failure of the test, and it will be necessary to replace the
unit.
5. Decrease engine rpms to idle. It may be necessary to turn on
a number of electrical devices to increase the electrical load
to cause the voltage to drop sufficiently. As the system voltage
falls below the set point, the voice message “CHECK VOLTAGE,
CHECK VOLTAGE” will be heard in the pilot’s headset, and the RED
warning light will illuminate. If the system fails to follow
this sequence, that constitutes failure of the test and it will
be necessary to replace the unit.
6. Individually turn on each electrical device in the aircraft.
As each device is powered up, verify that its operation is not
effected by the operation of the Volt & Vac alert, and that the
Volt & Vac is not effected by the operation on the device turned
on. Use the attached checklist as a guide. If any device fails
to operate properly, turn off the Volt & Vac alert to determine
if it is the cause of the malfunction. Any interaction between
the Volt & Vac alert and any other electrical equipment in the
aircraft constitutes failure of the test. The interference must
be resolved.
VI. DOCUMENTATION
1. The installer is responsible for making all logbook entries,
revising weight and balance, and other documentation as
required. Place the aircraft flight manual supplement (AFMS) in
the aircraft and provide the Instructions for Continued
Airworthiness to the owner for inclusion with his maintenance
records. The total weight of the Volt & Vac system components is
0.4 Lb., (0.34 lb. for the electronic module and .06 lb. for the
light assembly
