190-02246-10 GI 275 Part 23 AML STC Installation Manual
Rev. 11 Page 3-38
EMERGENCY POWER OPERATION CALCULATION EXAMPLE
Date: 08/04/2017 Registration No.:
N5272K
POWER SOURCE QTY. INSTALLED VOLTAGE MANUFACTURER MODEL
ALTERNATOR 1 13.75 VDC PRESTOLITE AL 12-P70
BATTERY 1 12.00 VDC GILL G-35
Assumptions:
1. Most severe operating condition is considered to be night IFR with the pitot heat operating.
2. Load demands are shown for steady state operation and do not include inrush current draw.
3. Load shedding is accomplished manually by the pilot within five minutes of warning
annunciation.
4. Loads measured using a calibrated Extech DC ammeter clamped on the cable between battery
terminal and master relay.
Analysis:
(1) Battery Capacity
0.75×35 Amp hrs = 26.25Ah×60 min = 1575 A-min
(2) Normal Operation Load [t
1
= 5 minutes duration]
Current drawn in normal cruise 43.5 A
Load 5 min×43.5 A = 217.5 A-min
(3) Emergency Landing Load [t
2
= 10 minutes duration]
Current drawn in emergency landing 48.1 A
Load 10 min×48.1 A = 481 A-min
(4) Emergency Cruise Load.
Current drawn in emergency cruise 34.0 A
(5) Battery capacity for emergency cruise
t
3
=
(1) - (2) - (3)
=
1575 - 217.5 - 481
= 25.8 minutes
(4) 34
(6) Total duration of flight on emergency (battery) power
t = t
1
+ t
2
+ t
3
t = 5 min + 10 min + 25.8 min = 40.8 min
Results:
The total required flight duration on emergency power is 30 minutes. The existing battery capacity
provides 40.8 minutes for emergency flight duration. The battery is adequate.
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