enhanced flight 2870A User manual

Model 2870A Manual p/n 752-638, Rev 20120906 Page 1 of 4
Operator’s Manual
Enhanced Flight™ Model 2870A
28V Aviation Ground Power Unit (GPU)
NOTE: This manual is also applicable to the Model 2835A, which is identical in appearance and operation,
except with a maximum continuous output of 35 amperes, instead of 70. If your GPU includes the optional, built-in
BatteryMINDer maintenance-type de-sulfating charger, a separate operator’s manual is provided for that feature.
IMPORTANT DISCLAIMER & OPERATING LIMITATIONS
Audio Authority authorizes this device for use ONLY by aviation professionals, such as licensed
pilots and maintenance technicians, knowledgeable about their aircraft electrical system and batteries.
Aircraft electrical systems vary widely. Many aircraft electrical systems have been altered in the field
from the original OEM configuration and these changes are often poorly documented in the aircraft
records. The operational concepts, recommendations, and instructions presented in this manual are
necessarily general and make assumptions that do not apply to every aircraft, and may not be correct
for your particular aircraft. Incorrect use of this device has the potential to damage the GPU and/or
aircraft components. It is the operator’s responsibility to read completely and fully understand this
manual, plus those sections of the Aircraft Flight Manual and Maintenance Manual that pertain to
their aircraft’s electrical system design, to determine the appropriate use of this, or any, external
power source. If you cannot do this, do not use this product. Instead, consult the airframe
manufacturer or a technician familiar with your specific aircraft type and configuration before
connecting the GPU to your aircraft.
2-Meter
Output Cable
with AN2551
3-pin Plug
100-240V AC
Line Cord
Removable Dual
Cord/Tool Caddies
Large Digital
Volt and Amp
Meters
Provision for Optional BatteryMINDer
Full-time De-Sulfating Charger

Model 2870A Manual p/n 752-638, Rev 20120906 Page 2 of 4
General Description and Application
The Model 2870A GPU is a modular switching-mode power supply designed to provide pilots and
aviation maintenance professionals with a portable, affordable source of stable, high-current, noise-free
DC power that replicates the in-flight electrical environment. Its rated output is 28 Volts DC, up to 70
amps continuous, from a 20A 120 VAC 60 Hz input. It will safely provide continuous power for the most
delicate electronics with stable, ripple-free DC up to its full rated output. It is ideal for:
•private aircraft hangars
•baggage-carried backup power source for remote sites
•FBOs, avionics & maintenance shops
•air shows and aircraft exhibitions
•aircraft production and testing facilities
Operation of sophisticated avionics and electrical equipment by poorly regulated, noisy power sources
risks costly damage. This portable GPU is designed as a practical alternative to large, expensive start
carts, battery chargers, and other transformer/rectifier-based power systems designed to turn electric
starter motors. It is suitable for ground operation of airframe systems such as:
•avionics for familiarization & training, database updates, testing or maintenance
•aircraft heating, air conditioning and ventilation systems
•cabin entertainment systems
•hydraulic and electric motors for actuating landing gear systems
•electrical equipment, motors, and lighting
•electronic equipment and gyros
Operating Conditions & Limitations
The 2870A GPU is fan-cooled and relies on unobstructed access for cooling air to enter the rear vents and
exit the bottom of the cabinet at the front. The GPU should operate on a clean, hard surface so that debris
cannot be ingested. Its design assumes a dry operating environment. If used outdoors, it is the operator’s
responsibility to insure that the unit is not exposed to moisture.
At full output, the GPU can draw up to 19 amperes and therefore should be connected to a dedicated 120
volt AC, 20-amp wall receptacle. Connecting the GPU to a standard 15-amp wall outlet will limit its
output to about 55A, but otherwise it will function properly. If an extension cord is to be used with the
GPU, a 3-pin grounded 12-gauge HD type of less than 50 feet is recommended – the shorter, the better.
Connecting GPU to Aircraft
Consult your Aircraft Flight Manual, Pilot’s Operating Handbook, or Aircraft Maintenance Manual for
the correct procedures for connecting an external power source to your particular aircraft. Our general
recommendation is to turn the GPU ON and observe its output voltage stabilized at approximately 28
volts before connecting its output cable to the aircraft’s external power receptacle. Similarly, we
recommend removing the GPU’s output cable from the aircraft prior to turning its power switch OFF.
This procedure will avoid any possibility of subjecting the aircraft electrical system to turn-on or power-
down transients. If the GPU voltage is less than 24 volts, do not connect to aircraft, of if connected,
discontinue operation and seek repair.
The GPU rear panel has a 20A circuit breaker. If the GPU shuts down while operating, turn its power
switch to the OFF position, disconnect it from the aircraft and check for any potential overload or short
circuit conditions. Once resolved, reset the circuit breaker, turn power switch to the GPU position to
restore GPU output, then reconnect to the aircraft.

Model 2870A Manual p/n 752-638, Rev 20120906 Page 3 of 4
Operation
The GPU is forced air-cooled with internal fans. If the fans are inoperative for any reason, the GPU
should be repaired before further use. The 2870A includes dual digital output meters on the front panel
for voltage and current. It is characteristic of the switching-mode power design to provide a nominal 28
VDC up to its full output. If the load exceeds 70 amps, the current display will flash to indicate an
overload condition and alert the user to reduce the circuit load to the GPU. Prolonged overload conditions
may damage the GPU.
Please use our website for the latest product information: http://www.audioauthority.com/GPU
GPU/Aircraft Compatibility
The 2870A GPU is compatible with all piston and turbine aircraft with 28 VDC electrical systems (24
volt batteries) that initially draw less than 70 amperes without optional equipment turned ON. This
includes most piston aircraft and a large number of turboprops and small jets. Current load on the GPU
can be observed with the built-in meter on the front panel. The GPU may also compatible with additional
aircraft where the initial load to the GPU can be reduced by pulling circuit breakers for non-essential
equipment such as lighting and environmental systems. This may require some experimentation to
determine the configuration that fits within the output limitations of the GPU, but once identified, the
configuration can be easily reproduced for subsequent ground power operation.
Battery Use and Charging Limitations
Connecting the GPU to the aircraft will replicate the 28VDC electrical flight environment. If the aircraft’s
battery is in-circuit with the GPU output (by engaging the Battery Master switch in many aircraft) the
battery will benefit from the GPU “topping off” the battery, just as it would in flight. Be aware that the
initial load to the GPU will be slightly and temporarily higher, even with a well-charged battery, until the
battery’s demand on the GPU is satisfied. This can be observed as the GPU’s amp meter ticks down over
a period of minutes until stabilized. Operating the GPU with the battery in-circuit for a period of several
hours should not cause any problems. In addition, if the GPU is used to operate devices where the inrush
current is greater than 70 amps (hydraulic gear motors, electric air conditioning, etc.), supplying the surge
amperage from the ship’s battery is recommended and will facilitate operation of these devices, so long as
the continuous load is not in excess of the GPU’s output. Similarly, topping off a serviceable battery with
the GPU in preparation for engine start will improve battery output and starting performance.
The 2870A GPU is NOT an automatic battery charger:
•It cannot isolate the ship’s battery from the rest of the electrical system and contains no circuitry to
monitor or evaluate the battery’s level of charge.
•It will not automatically turn off when the battery is fully charged.
•Its output voltage is fixed at 28 volts DC and is not compensated for non-standard temperatures.
•It cannot vary the output current in response to battery temperature or charge condition, so a deeply
discharged battery may recharge too rapidly, risking battery damage and acid spillage.
A deeply discharged battery (less than 22 volts on the ship’s volt meter) should be removed from the
aircraft and serviced in accordance with the aircraft Maintenance Manual before returning to service.
GPU Start Assist (piston engines only)
The GPU may be used for piston engine start assist with a well-charged battery. Check that the following
precautions have been complied with before proceeding:
•GPU and all cables are well clear of the propeller arc and that once engine has been started,
cables can be unplugged from the aircraft, the GPU removed, and the aircraft external power

Model 2870A Manual p/n 752-638, Rev 20120906 Page 4 of 4
receptacle secured without danger to ground personnel or the aircraft. Consult your Aircraft
Flight Manual for procedures for starting with external power.
•Resting battery voltage must be at least 23 volts on the ship’s meter. If less, allow time to top-off
battery charge, or if deeply discharged, remove the battery from the aircraft for service in
accordance with the manufacturer’s instructions before returning to service.
WARNING!
Do not attempt flight with a battery not fully charged. In the event of an
electrical system failure, the battery’s capacity to operate the aircraft
electrical equipment would be severely diminished, which could
jeopardize safety of flight, risking property damage and lives.
NOTE
The 2870A GPU is adequate for piston engine start ASSIST ONLY. Its
capacity is inadequate for turbine engine motoring or starts and should be
used for airframe systems power only. Do not attempt turbine engine
motoring or starts with the GPU connected to aircraft.
Specifications:
Input: 110-240 Volts AC, 50-60 Hz, up to 19 amps (9.5 amps Model 2835A)
Output: 28.3 +/- 0.5 Volts DC, 70 amps continuous (35 amps Model 2835A)
Shipping Weight: 33 lbs / 15 kg (Model 2835A 28.6 lbs / 13 kg)
Chassis Dimensions: 8.75”H x 11.38” W x 18.38”D (22.2 cm x 28.9 cm x 46.7 cm)
One Year Limited Warranty
Model 2870A Ground Power Units are warranted to the original purchaser to be free of defects in
materials and workmanship for a period of one year from date of shipment. If you suspect a failure please
see our Service Policies online at http://www.audioauthority.com/page/Service_policy, or contact our
service department for instructions.
Service Department
Audio Authority Corporation
2048 Mercer Road, Lexington, KY 40511
Phone: [phone] (or 859-233-4599)
Email: [e-mail]
Units received that are in-warranty will be repaired without charge. Units returned for service must be
shipped freight. Units repaired under warranty will be returned freight prepaid via UPS ground or
equivalent. A repair estimate will be provided for out-of-warranty repairs. This warranty is void for
products that, in our opinion, have been subject to overload, moisture, accident, damage, alteration,
misuse, abuse, or acts of nature.
THE SOLE AND EXCLUSIVE REMEDY UNDER THIS WARRANTY IS LIMITED TO REPAIR OR
REPLACEMENT AS SPECIFIED ABOVE. THERE ARE NO OTHER WARRANTIES EXPRESSED OR
IMPLIED. SPECIFICALLY, BUT WITHOUT LIMITATION, THERE ARE NO IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL AUDIO
AUTHORITY BE RESPONSIBLE FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
FROM ANY DEFECT, OR FAILURE TO OPERATE PROPERLY, OR ARISING OUT OF ANY BREACH OF
THE WARRANTY MADE HEREIN.
No person is authorized to give any other warranty or to assume any additional obligation or liability on
behalf of Audio Authority Corporation, without its express written approval.