Flashcards in Interview Questions Deck (47)
Approaching Mach 1 center of life moves so far rearward that’s there’s not enough elevator control to maintain level flight. The nose pitches down and AC accelerates more.
One wing travels faster and becomes straighter to the relative wind creating more lift and hence a roll. The extra lift creates extra drag resulting in opposite yawing motion, creating another dutch roll.
-increases critical Mach # by splitting air into spanwise and cordwise vector
-better high speed stability and handling
- more efficient and less drag at high speeds
- Increased approach and landing speeds
-poor slow speed stability and handling
- less desirable stall characteristics
Lowest Mach number which airflow over any part of the AC reaches the speed of sound.
Where on the AC would reach critical Mach first?
Edge of an AC’s high altitude operating envelope. Speed between high speed buffet (Mach buffet) and low speed buffet (stall).
How do we counteract Dutch roll?
Perfect coordination and yaw dampers.
Stages of a thunderstorm.
-Cumulus: lofting, updrafts, rapid vertically building clouds.
-Mature: most violent, rain begins, all hazards are their greatest.
Going around a T storm
Upwind are least 20 miles. Avoid anvil (downwind) by at least 1 mile for every kt of wind at height of anvil.
What is a diffuser and where in a turbine?
Diffuser slows down compressor delivery air to reduce flow losses in combustor. Slower air required to help stabilize combustion flame and the higher static pressure improved combustion efficiency. Slows down high velocity air to increase air pressure in a centrifugal compressor.
Where does bleed air come from?
Depends on engine, but comes from compressor section. On the CRJ the 10th and 14th stages of the compressor.
What does bleed air provide?
Inter-cooling of engine, cross starting another engine, engine and airframe anti-icing, cabin pressurization, pneumatic actuators, air driven motors, pressurization the hydraulic reservoir, and waste/water storage tanks. 10th stage is used for pneumatic starting and air conditioning. 14th is used for anti-ice and thrust reverse.
Low pressure compressor speed reading in % of RPM.
Connected directly to low pressure turbine.
Used to set power for cruise, climb, takeoff. It is a tach generator sending signal for reading.
High pressure compressor read in % of RPM.
Connected directly to high pressure turbine.
Another tach generator.
Which moves more air, the bypass or the core?
Bypass, 80-86% of air intake.
Moving blades connected to drive shafts, usually for tree design.
Stationary blades used to direct airflow.
Air that goes around the core of the engine. 80-86%.
Air that goes through the core and gets compressed, ignited.
Accessory gear box
Usually uses a tower shaft from the compressor or turbine to drive accessories for the AC. Hydraulic pumps, generators, fuel pumps, oil pumps, ATS (air turbine starter)...
Constant speed drive (CSD)
A device used to turn the generator at constant speed. Similar to prop governor it operates in three modes underspeed, over speed, and on speed.
Where does most of the thrust in the turbo fan come from?
Bypass air provides most of the thrust.
What is the difference between a turbofan and turbojet.
Bypass is major difference. Turbojet is not as efficient and is loud but has good high altitude characteristics.
A turbofans bypass produces most of the thrust for an engine, is more efficient and quieter. Has good low altitude, low speed characteristics. The fan is kind of like a prop for low altitude and speed while the core is like a turbojet in cruise.
Sections of a turbine engine:
Fan - low pressure compressor - high pressure compressor- combustion chamber - high pressure turbine - low pressure turbine - nozzle
Types of drag:
Induced: byproduct of lift
Parasite: form, skin friction
What is MDA?
What do you need to descend below it?
Min descent altitude.
If established on approach course before FAF and ATC reports wx below mins can you continue?
Before FAF you must go around. After if you have your mind you can continue. 121.651
Where is the FAF in ILS?
FAF is glideslope intercept.
If vis met mins, but was reported as less how you say you determined this?
By visual reference, I broke out at mins. Flight vis is the average forward distance from cockpit in flight which prominent unlighted objects can be see in the day and lighted can be seen at night.