Subsection 14 Electromagnetic Environment

Question 1

Group 2 lightning damage to aircraft is?

Answer 1

Damage to avionic equipment

Question 2

A fault is reported on a coaxial cable used in the HF system, what device would you use to locate the fault?

Answer 2

Time domain reflectometer

Question 3

A lightning strike on an aircraft causes structural damage at the?

Answer 3

Entry and exit points

Question 4

An aircraft may have been HIRF affected a?

Answer 4

Static wick check is required

Question 5

Degradation of an aircraft electromagnetic protection may be caused by?

Answer 5

Corrosion

Question 6

Electromagnetic compatibility is achieved by?

Answer 6

Shielding, screening, earthing, bonding and interference filters

Question 7

Electromagnetic compatibility is the ability of equipment to operate satisfactorily in its EM environment without introducing?

Answer 7

Intolerable EM disturbances to other electrical devices in that environment

Question 8

For braided cables the amount of braiding keeps?

Answer 8

Radiated power inside the emitting assembly or away from the susceptible circuit

Question 9

An ESD wrist strap should be worn whenever handling electrostatic sensitive devices, this is to protect the device from?

Answer 9

ESD damage

Question 10

HF aerials are protected against lightning strike by?

Answer 10

Spark gap

Question 11

HIRF is an acronym for?

Answer 11

High intensity radiated field

Question 12

HIRF protection of LRU’s is provided by?

Answer 12

Built in filters and overvoltage circuits

Question 13

In an aircraft system, conducted interference can be reduced by introducing?

Answer 13

Filters in the appropriate lines

Question 14

In an aircraft system, conducted interference causes interference through?

Answer 14

The aircraft’s wiring

Question 15

In order to maintain HIRF protection, bonding checks between airframe and electrical components carrying voltages >50volts RMS or DC or main earth return should not exceed?

Answer 15

1 ohm

Question 16

Manufacturers of aircraft can ensure HIRF protection by designing?

Answer 16

Specific avionic areas that are shielded against HIRF

Question 17

Ribbon cables effected by mutual impedance and current loop leakage should be protected by?

Answer 17

Earthing each alternative conductor to a separate point

Question 18

Testing of HIRF on aircraft systems is done?

Answer 18

At and during production and testing

Question 19

To protect an aircraft structure manufactured from composite materials from the effects of lightning strike a layer of ?

Answer 19

Conductive fibres or screens is embedded between layers of the composite material to conduct lightning current

Question 20

To reduce HIRF on radio equipment, ensure?

Answer 20

All static wicks are in place.

Question 21

To shield a fibre optic from EMI you must use?

Answer 21

An opto-isolator

Question 22

To stop earth loops forming you would earth only?

Answer 22

One end of the cable screen

Question 23

What is the most probable primary cause of HIRF failure?

Answer 23

Unserviceable radio filters

Question 24

When carrying out a bonding check on a surface protected by anodic film the?

Answer 24

Anodic film should be removed locally to ensure a good contact

Question 25

When carrying out airframe bonding checks as part of a programme of HIRF prevention the bonding resistance should be?

Answer 25

<50 Milliohms

Question 26

When clamping cable looms containing co-axial cables, avoid distortion to the co-axial cable to?

Answer 26

Maintain the dielectric constant

Question 27

When incorperating an aerial cable it must be?

Answer 27

Positioned separately from the loom

Question 28

Which of the following could be a primary cause of HIRF protection failure?

Answer 28

Unserviceable radio filters