Chapter 4 - Turbine Engine Operations, Maintenance, & Overhaul Flashcards
What can and cannot be used to mark components during inspections?
Materials approved for:
Hot and Cold Sections
- Chalk
- Special layout dye
- Some commercial felt-tip applicators
- Marking pencils
Cold Sections ONLY
- Wax or grease marking pencils
Never use a common graphite-lead pencil or any marker that leaves a carbon, copper, zinc, or lead deposit
What two techniques are commonly used to repair engine exhaust sections constructed of stainless steel?
Insert gas welding
Electron beam welding
Typically, combustion liners are constructed of stainless steel and be repaired using either ____ or _____. After a component has been welded, it must be _______to relieve any stress building caused by the welding process.
Inert gas or electron beam welding.
heat-treated
When replacing a turbine or compressor blade, what must it be marked with?
Marked with a code indicating moment -weight in inch-ounces ir inch-grams
What is QECA?
Quick engine change assembly -
powerplants removed from an airframe with the appropriate accessories installed to reduce the time an aircraft is out of service.
Define
TBO
FOD
Hot Start
TBO - Time between overhaul
FOD (Foreign object damage) - occurs any time something is drawn into a gas turbine engine. Whenever this occurs, the engine must be inspected.
Hot start - Ignition with an excessively rich fuel/air mixture. Always require an engine inspection.
Name several methods commonly used to remove an engine from an aircraft?
Dolly - positioned under the engine
Hydraulic lift - lift raises the mount for attachment to the engine
Hoist and a sling
What is weather checking?
Cracking of the outside covering of hoses that sometimes penetrates to the reinforcement webbing
What is cold flow?
Deep and permanent impressions or cracks caused by hose clamps
What is modular construction?
An engine that has been designed as a set of seperate modules (or sections) assembled together.
Is the overhaul of an engine considered a minor or major repair?
Major repair
What can cause hot streaking?
Unatomized fuel contacting the combustion liner and then burning.
What are the three types of blade creeps?
Primary creep - occurs during an engine’s first run; this is when new blades experience operational stresses for the first time
Secondary Creep - occurs slowly during many hours of operation. Engine manufacturers take secondary creep into consideration when establishing a turbine’s service life.
Tertiary Creep - occurs at an accerlerated rate after a period of secondary creep. The onset of tertiary creep is attributed to hot starts, overtemperature events, extended operation at high power settings, and blade erosion.
How can cause bearings to become magnitized? How do you unmagnitize it?
Research shows that a bearing can become magnitized from rotation at high speeds, lightning strikes absorbed by an aircraft, and arc welding on the engine with improper grounding.
A magnetic field detector is used to determine if a bearing has been magnitized.
The process of unmagnitizing (degaussing) involes placing the part near an electromagnetic coil that is creating an alternating magnetic field until the magnetic field of the bearing is no longer.
Spraying an atomized metallic material onto the base metal of a part at a high velocity and at a high heat temperature is called what?
Plasma Coating
