7.19 Abnormal Events

Question 1

Lightning most likely to strike when?

Answer 1

Altitudes of 8000 to 14000 ft.

Question 2

How often do lightening strikes occur

Answer 2

Approx. Every 3000 flying hours.

Question 3

Lightning strikes

Answer 3

Produces a current which flows across the aircraft skin until it encounters a discontinuity where it produces a spark.
Modern construction techniques have almost eliminated this.

There are always at least two strike points, an entry and an exit.

Question 4

Two types of damage that lightening causes

Answer 4

Direct damage.
- metallic structures which are burned, melted, or show signs of metal distortion and non-metallic structures which are damaged.

Indirect damage
- damage to electrical / electronic systems.

Question 5

Usual areas where lightening strike damage occurs

Answer 5

Nose section and radomes.
Engine nacelles
Wing tips.
Horizontal stabiliser tips and elevator tips.
Vertical fin tips and rudder tip.

Question 6

Areas lightening does not likely strike.

Answer 6

Drain masts.
Pilot probes.
Blade antennas.
Extended ends of leading edge slats.
Trailing edges of flap track fairing tips.
Lading gear.

Question 7

Indirect lightening damage

Answer 7

High intensity lightening produces electromagnetic field. Which can damage instruments.

Question 8

What is HIRF

Answer 8

High intensity radiated fields.

Question 9

What is hirf

Answer 9

Electromagnetic radiation that can damage an aircraft’s electronic systems

Question 10

Most easily detectable sign of a heavy landing?

Answer 10

Wrinkled skin.