7.19: Abnormal Events Flashcards
What altitude of lightning strikes?
8000 ft to 14000 ft
Where are lightning strikes most often occurred?
Landmasses as they are a source of weather changes
How often approximately does lightning strikes occur?
Every 3000 flight hours
What are the two strike points on an aircraft structure?
At the entrance point
At the exit point
When lightning strikes, where does it commonly enter and move?
It usually enters the forward fuselage or engine, and tends to move rearwards over the fuselage surface or over the wing surface
On the wing, how does lightning move?
Moves aft of the nacelle/pylon or aft and outboard towards the wing tips
When Lightning strike the empennage or wing surface, what happens?
It stays there until the lightning current stops
What type of damage indicates what type of lightning strike?
1/8 inch in diameter indicates a lightning strike, while holes of 1/4 inch in diameter can be possible if the lightning strike intensity is high
What are used on radomes to divert lightning strikes?
Lightning strike diverter strips
What can high intensity produce and cause damage to?
Produces EMF that are large enough to cause damage to the electrical cables and components within the unpressurised areas of the aircraft
What are bonding leads attached to and why?
Attached to both the surface of flight controls and the aircraft structure to provide a low resistance path so bearing damage can be avoided
What type of fastener s are used in critical areas and why?
Non-ferrous fasteners so they they don’t become magnetised during lightning strikes and cause system problems
What are static discharges used for?
Used to stop static charges from building up from the friction of the airflow. Frequently damaged by lightning strikes
What is HIRF and what can it affect?
EM radiation that can affect the aircraft’s electric and electronic systems
Transmitters within the aircraft operate in the frequency of what and can cause what?
10 to 40 GHz and is capable of causing HIRF
Can HIRF be caused by lightning strikes directly or indirectly?
Both directly and indirectly (in the vicinity of the aircraft)
What are three primary areas to be considered for the HIRF protection integrity?
-Aircraft structure
-Electrical wiring installation protection
-Equipment protection
If aircraft magnetism is suspected, what does it require?
The aircraft requires degaussing (demagnetism) followed by a calibration compass swing
When is the inspection done to determine when an aircraft is suspected to have a heavy landing?
If the aircraft has exceeded its MDLW (Maximum Design Landing Weight)
What is an indication of a heavy landing on the structure of aircraft?
Creased or wrinkled skin
How many phases are a hard landing inspection divided into?
2 phases
What is a phase 1 inspection?
Applicable when a hard landing or high/side load landing occurs. The goal is to determine if more inspection are required, with the inspections being kept as simple as required
What are common areas for phase 1 inspection?
-Main landing gear struts
-Structural components
What condition makes a high drag/side-load landing occur when landing?
-The aircraft skidded or overran the prepared surface
-The aircraft made a landing short of the prepared surface
-The aircraft made a landing and two or more tyres were blown
-The aircraft skidded a sufficient amount
