Learjet 35 PTM Chapter 2 (Electrical)

Question 1

The generators are rated for __ Volts and ___ Amps

Answer 1

30 V, 400 A

Question 2

The Emergency battery can operate what three things?

Answer 2

Stand by attitude Gyro
The landing gear
The flaps

Question 3

How long can the main batteries power the minimum equipment for night instrument flight?

Answer 3

30 min

Question 4

What is connected to the L BAT BUS?

Answer 4

L STALL WARN
LIGHTS (Step Lights, Door Lights, Cockpit lighting, Baggage, and Tailcone lighting)
DOOR ACTR Motor

Question 5

What is connected to the R BAT BUS?

Answer 5

R STALL WARN

Question 6

Each battery connects to its respective battery hot-bus through a __ Amp current limiter.

Answer 6

20 Amp current limiter
(This protects the hot wired items - stall warning, lights, door actr)

Question 7

The DC voltmeter is connected to what?

Answer 7

Battery charging bus through a 5 Amp current limiter

Question 8

Generator voltage is regulated to ____ VDC for lead acid batteries

Answer 8

28.8 VDC

Question 9

What does depressing the generator reset button do?

Answer 9

It resets the overvoltage relay, and completes a power circuit to the voltage regulator. This resets the generator.

Question 10

At least one battery switch must be turned on to close the GPU control relay. If the voltage is below ___ V, The power relay closes to complete a GPU-to-battery charging bus connection.

Answer 10

33 V

Question 11

If GPU voltage exceeds 33 V, the overvoltage circuit causes the power relay to open, thereby disconnecting the GPU from the electrical system to prevent damage to voltage sensitive equipment. Can this be reset?

Answer 11

No, it needs to be sent to Learjet for Replacement.

Question 12

The AFM recommends that a GPU be used for engine start when ambient temperatures is __°C or below.

Answer 12

0°C

Question 13

There are two types of current limiters. The lower amperage and higher amperage. How do you tell the difference?

Answer 13

The lower amperage (<50 A) are red and have a pin that protrudes if blown
The higher amperage are made of a gray ceramic material with a small window that allows visual inspection.

Question 14

What will our situation become if both 275 Amp current limiters fail in flight?

Answer 14

The batteries are no longer being charged by the battery charging bus. Our DC Volt meter will read battery voltage. We have about 30 minutes before our main batteries are depleted and we switch over to emergency battery power.

Immediately find and remain in VMC, declare an emergency, run the respective checklists, land as soon as possible!

Question 15

What purpose do relays serve?

Answer 15

They allow the control circuit wiring to be a lighter gauge since less current is required to operate the relay… vs. what is the alternative?

Question 16

On FC – 200 AFCS aircraft where are the additional auto pilot circuit breakers?

Answer 16

Under the pilot seat on the auto pilot electric box

Question 17

The DC circuit breakers are the ________ type, and the AC circuit breakers are the ________ type.

Answer 17

DC - Thermal
AC - Magnetic

Question 18

If you unplug the GPU or both generators fail, will the Freon AC or auxiliary heater turn off?

Answer 18

No! It is the pilot’s responsibility to turn those off to preserve battery life.

Question 19

What are the numbers on each circuit breaker?

Answer 19

Amperage ratings

Question 20

Where are the inverters located in the aircraft?

Answer 20

The tail cone

Question 21

If you have an auxiliary inverter, when should it be operated?

Answer 21

It is recommended that it be operated all the time in conjunction with the primary and secondary inverters in order to extend inverter life.

Question 22

What is the voltage output of the inverters?

Answer 22

115 VAC

Question 23

A __________ takes 115 VAC and steps it down to 26 VAC for some instruments and avionics.

Answer 23

Transformer

Question 24

The PRI Inverter current goes to the ____ BUS, which means the SEC Inverter powers the ____ BUS.

Answer 24

PRI - Left BUS
SEC - Right BUS

This is important to understand because if your aircraft has an auxiliary inverter, we need to know which BUS to send power to if an inverter fails.

Question 25

When we turn on the emergency battery during the cockpit check, the small amber EMR PWR light comes on. Why does this come on?

Answer 25

The EMR PWR lights illuminates when the emergency battery is NOT being charged. (When it is discharging). If this light comes on at any time in flight, It means the normal electrical system has failed.

It is recommended to place the switch to standby until gear or flap operation is required in order to conserve battery life

Question 26

What is powered when the EMER PWR switch is ON?

Answer 26

Stand by attitude indicator and back lighting.
Landing gear control circuits and green position lights.
Flap control circuits, but not flap indicator.
RVSM Pilot altimeter.
STBY Altimeter Vibrator.

Question 27

What is a standby altimeter vibrator?

Answer 27

It is a vibrator that shakes to reduce friction errors and to prevent the indicator from sticking!

Question 28

Battery life for the Emergency BATT is ________ on STBY, and ________ in the ON position.

Answer 28

3 hrs 45 min on STBY
30 min in the ON position

Question 29

If there are two emergency batteries, what typically will the second emergency battery power?

Answer 29

At least one radio for communication. It can sometimes also power NAV 1, a transponder, and the TCAS system

Question 30

Draw out as much of the electrical system as you can. Refer to the PTM 2-22,23

Answer 30

PTM 2-22,23 (Depending on Serial #)