AET Electrostatic Discharge (ESD) and Component Handling

Question 1

What is the primary danger of improper ESD handling when working on avionics circuit boards?

Accepted Answer

Invisible damage to semiconductor junctions that may cause immediate failure or weaken the component for later in-service failure

Answer

A static discharge can damage or destroy the extremely thin gate oxide layers in MOSFETs and other semiconductor junctions without any visible sign. 'Latent' ESD damage may not cause immediate failure but will reduce the device's reliability and life span.

Question 2

When must a technician wear a properly grounded ESD wrist strap while working on avionics?

Accepted Answer

Whenever handling any ESD-sensitive (ESDS) device or assembly, regardless of environment

Answer

ESD-sensitive devices must be protected regardless of humidity, clothing type, or work area. Even low static levels invisible to human senses can damage ESDS components. The wrist strap provides a continuous path to drain static charge safely.

Question 3

What resistance value should a properly functioning ESD wrist strap measure when tested with a wrist strap checker?

Accepted Answer

Approximately 1 megohm (1 MΩ)

Answer

A correctly functioning ESD wrist strap contains a 1 MΩ resistor in series. This provides enough resistance to protect the technician from electrical shock while still allowing static charge to drain safely to ground. A dead short (0 Ω) would create a shock hazard.

Question 4

How should an ESD-sensitive avionics LRU be transported between the aircraft and the avionics shop?

Accepted Answer

Transported in approved ESD-protective (conductive or dissipative) packaging

Answer

ESDS assemblies must be transported in approved ESD-protective packaging — conductive bags, dissipative foam, or other approved containers. Standard cardboard and plastic bubble wrap are insulators that can generate and hold static charge, increasing the risk of ESD damage.

Question 5

What does the international ESD symbol (a hand inside a triangle with a diagonal bar) on an avionics component label indicate?

Accepted Answer

The component is ESD-sensitive and requires proper ESD handling procedures

Answer

The ESD symbol (hand-in-triangle with slash) is the internationally standardized marking indicating that the item is ESD-sensitive (ESDS) and must be handled, stored, and transported using ESD protective measures to prevent damage.

(AET) Aircraft Electronics Technician Practice Test

(AET) Aircraft Electronics Technician Practice Test

AET Electrostatic Discharge (ESD) and Component Handling