Subsection 14 Electromagnetic Environment Flashcards
Group 2 lightning damage to aircraft is?
Damage to avionic equipment
A fault is reported on a coaxial cable used in the HF system, what device would you use to locate the fault?
Time domain reflectometer
A lightning strike on an aircraft causes structural damage at the?
Entry and exit points
An aircraft may have been HIRF affected a?
Static wick check is required
Degradation of an aircraft electromagnetic protection may be caused by?
Corrosion
Electromagnetic compatibility is achieved by?
Shielding, screening, earthing, bonding and interference filters
Electromagnetic compatibility is the ability of equipment to operate satisfactorily in its EM environment without introducing?
Intolerable EM disturbances to other electrical devices in that environment
For braided cables the amount of braiding keeps?
Radiated power inside the emitting assembly or away from the susceptible circuit
An ESD wrist strap should be worn whenever handling electrostatic sensitive devices, this is to protect the device from?
ESD damage
HF aerials are protected against lightning strike by?
Spark gap
HIRF is an acronym for?
High intensity radiated field
HIRF protection of LRU’s is provided by?
Built in filters and overvoltage circuits
In an aircraft system, conducted interference can be reduced by introducing?
Filters in the appropriate lines
In an aircraft system, conducted interference causes interference through?
The aircraft’s wiring
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?
1 ohm
Manufacturers of aircraft can ensure HIRF protection by designing?
Specific avionic areas that are shielded against HIRF
Ribbon cables effected by mutual impedance and current loop leakage should be protected by?
Earthing each alternative conductor to a separate point
Testing of HIRF on aircraft systems is done?
At and during production and testing
To protect an aircraft structure manufactured from composite materials from the effects of lightning strike a layer of ?
Conductive fibres or screens is embedded between layers of the composite material to conduct lightning current
To reduce HIRF on radio equipment, ensure?
All static wicks are in place.
To shield a fibre optic from EMI you must use?
An opto-isolator
To stop earth loops forming you would earth only?
One end of the cable screen
What is the most probable primary cause of HIRF failure?
Unserviceable radio filters
When carrying out a bonding check on a surface protected by anodic film the?
Anodic film should be removed locally to ensure a good contact
When carrying out airframe bonding checks as part of a programme of HIRF prevention the bonding resistance should be?
<50 Milliohms
When clamping cable looms containing co-axial cables, avoid distortion to the co-axial cable to?
Maintain the dielectric constant
When incorperating an aerial cable it must be?
Positioned separately from the loom
Which of the following could be a primary cause of HIRF protection failure?
Unserviceable radio filters
