Oral Prep - Bleed Air Flashcards
What does 10th stage bleed air supply?
Engine starting, air conditioning, avionics cooling and pressurization
What does 14th stage bleed air supply?
Wing and cowl anti-ice systems and thrust reversers.
If for some reason the L/R 14th stage bleed air switchlights are not pressed in, what systems will not work?
Anti-Ice and Thrust reversers.
In this situation, if the Thrust Reverser switches are Armed, how would you know they will not work?
EICAS will not post a green L REV ARMED or R REV ARMED msg, but there will be a white Status msg for L 14TH SOV CLSD and R 14th SOV CLSD.
Describe the function of the TEST position of the DUCT MONITOR SELECTOR switch?
Simulates an overheat in both the 10th and 14th stage manifolds and the wing anti-ice duct.
Describe the function of the LOOP A/B positions?
Tests the individual loops of the 10th stage leak detection system for shorts or failure.
What does a red DUCT FAIL in the 10th or 14th stage switchlight indicate?
A leak (duct failure) in the associated duct section.
What does the amber FAIL light in the LCV switchlight indicate?
The APU LCV is stuck in the open position when commanded closed by the interlock protection or pilot.
Will the APU LCV open when the left 10th stage bleed switchlight is OPEN.
No
Will the APU LCV open if the right 10th stage bleed switchlight is pressed OPEN with the ISOL valve CLOSED?
Yes
What prevents backflow of high pressure bleed air from the manifold?
A check valve and APU LCV interlock (switch position logic)
Briefly describe the bleed air leak detection and warning system, dual or single loop, what is monitored, etc.
The bleed air leak detection and warning system monitors all pneumatic ducting from the engine pylon, fuselage and wing areas.
The 10th stage bleed system uses a dual loop overheat detection system, with a single loop provided for the 14th stage. The wing anti-icing system uses a single overheat loop in the fuselage and thermal sensors in the wing leading edges.
Why can you start both engines on the ground with the APU but the only choices to start an engine in flight, are Starter Assisted Cross Bleed Relight, or Windmilling Relight, except in the case of Double Engine Failure?
The 10th stage pneumatic system receives bleed air from either the engines, APU or external highpressure air. Bleed air from the 10th is used for engine starting, air conditioning, and pressurization. APU bleed air is modulated through the LCV, allowing APU bleed air to enter the left side of the manifold. To prevent the back-flow of high pressure 10th stage bleed air from the manifold, a check valve is installed in the APU bleed duct to prevent damage. The APU LCV interlock provides a second level of protection. With one engine operating in flight the check valve and LCV interlock protect the APU by closing it off form the bleed air system. That only leaves the option of using a cross bleed starter assist or windmilling procedure.
