PHI GOM S-92 - ELECTRICAL SYSTEM

Question 0

How are the two main AC Generators cooled?

Answer 0

Spray oil cooled from the main gearbox oil system.

Question 1

Electrical output of the S-92A main generators?

Answer 1

Three-phase 115/200 VAC
420 Hz
60-75 KVA
Peak of 90 KVA during emergencies.

Question 2

How is the APU Generator cooled?

Answer 2

Air Cooled.

Question 3

What frequency do the brushless AC generators produce at 105% Nr?

Answer 3

420 Hz

Question 4

What is the peak KVA rating of the APU GEN?

Answer 4

peak 45KVA

(main gen peaks at 90, double the APU)

normal 30-35 KVA

Question 5

How is DC electrical power produced in the S-92A?

Answer 5

Through 2 primary 400 amp DC converters located in the nose electronics bay.
A 125 amp backup converter in the #2 avionics rack will produce DC power if both primary converters fail.

Question 6

What external electrical power is available with the S-92A?

Answer 6

AC - 6 pins. 1 for each of the three phases and ground. 2 small pins for ext power monitor

DC - 2 pins

Ref: S-92 MTM ATA Chap 24

Question 7

What indication is available to alert the pilot the external power is connected to the aircraft?

Answer 7

EXT PWR CONNECT - ADVISORY

Question 8

What electrical equipment is shed if only the APU GEN is supplying electrical system power?

Answer 8

The K-5 relay sheds these items:

WARM Air

Windshield Heat (pilot side is recoverable)
AVC
RIPS
#1 Engine Anti-Ice Matts 
Air comp #2 if i stalled

Question 9

What indication is displayed if Engine anti-ice is on and the pilot windshield override switch is activated with only APU GEN electrical power available?

Answer 9

APU OVERLOAD - CAUTION

Question 10

What electrical equipment is lost if one main AC Generator fails?

Answer 10

NONE

Question 11

Should you turn off the Battery switch for a BATT HOT caution?

Answer 11

No, Land as soon as Practical.
The Battery Hot Relay will automatically disengage charging of the battery from the #1 DC Converter, allowing it to discharge into the Utility and Holdup Busses and cool the battery.

Question 12

Above what temperature does the BATT HOT caution activate?

Answer 12

70 C

Question 13

Below what temperature does the BATT HOT caution extinguish?

Answer 13

63 C

Question 14

What electrical equipment is lost if one DC Converter fails?

Answer 14

None

Question 15

The #1 DC Converter normally powers what busses? (UH-1)

Answer 15

(UH-1)
#1 DC Primary
Batt Utility
Batt Holdup

Question 16

The #2 DC Converter normally powers what busses? (2BE)

Answer 16

(2BE)
#2 DC Primary
DC Essential
Battery

Question 17

After a dual DC Converter failure, the Backup Converter and Battery will power what busses?

Answer 17

B/U converter powers
DC Essential 
(Items Essential for IFR flt)
Battery bus
(items for VFR flt)

Battery powers:
battery Utility
battery Holdup

(Utility and Holdup are always powered by the same source)

Question 18

What avionics equipment in the cockpit is powered after a Dual DC Converter failure? What instrument approches are available.

Answer 18

Pilots MFD #3 and #4
Pilot Nav instruments (ILS, VOR, ADF)
Pilots AHRS
#1 RTU
#1 FMS

You can shoot all approaches from the pilots side. For GPS you will need to couple to the CP FMS side #1. All comms/NAV will be set through the CP RTU.

Question 19

In flight the AC Gens will drop off line at what Nr?

Answer 19

80%

95% on deck

Ref: S-92 MTM ATA Chap 24

Question 20

What are the four items powered with the battery switch off and from what bus?

Answer 20

Fuel Precheck (Press fuel without bat on)
Fuel selector valves (fuel crossfeed no AC pwr)
External power receptacle (allows ext pwr)
Battery control

powered by Battery Utility bus

Question 21

What does the AC Generators PMG provide power to?

Answer 21

The PMG (permanent magnetic generator) supplies the GCU only.

Ref: S-92 MTM ATA Chap 24