Hydraulics and Pneumatics Flashcards
7 cards from real AMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hydraulics and Pneumatics flashcards as text
What is the consequence of using an incorrect AN/MS fitting torque when assembling an aluminum hydraulic tube fitting?
Answer: Under-torque causes leaks; over-torque crushes the flare and causes failure or leaks
Under-torqued fittings leak at the flare seat; over-torqued fittings collapse the aluminum flare, creating a path for leakage or immediate structural failure.
In an aircraft nose-wheel steering hydraulic system, what is the purpose of a centering cam?
Answer: To automatically center the nose wheel when weight is off wheels for gear retraction
A centering cam mechanically aligns the nose wheel to the straight-ahead position as the gear retracts so the wheel fits properly into the wheel well.
What is the purpose of the compensator port (vent port) in a master cylinder of an aircraft brake system?
Answer: To allow excess brake fluid to return to the reservoir when brakes cool and fluid contracts
The compensator port connects the brake line back to the reservoir when brakes are released, accommodating fluid volume changes due to thermal expansion and contraction.
When is it acceptable to repair a kinked aircraft hydraulic tube by straightening it?
Answer: Never; kinked tubing must be replaced because the kink work-hardens the material and creates a fatigue crack site
Straightening a kinked tube does not restore the original grain structure; the deformed area remains a stress concentration prone to fatigue failure and must be replaced.
What does a hydraulic system bootstrap reservoir accomplish that a simple vented reservoir cannot?
Answer: It uses system pressure to pressurize the reservoir, ensuring positive pump inlet pressure at high altitude
A bootstrap (pressurized) reservoir applies hydraulic system pressure to the fluid surface, guaranteeing adequate pump inlet head pressure where atmospheric pressure is too low at altitude.
Which condition requires immediate removal and replacement of a flexible hydraulic hose?
Answer: Any visible leakage, exposed wire braid, or a kink that reduces the internal bore
Leakage, exposed reinforcement braid, or kinking all compromise structural integrity and are cause for immediate replacement regardless of age.
In a pneumatic de-icing system using bleed air, what is the function of a pressure-reducing and shut-off valve (PRSOV)?
Answer: To simultaneously reduce bleed-air pressure to boot operating pressure and act as an on/off control valve
A PRSOV combines two functions—reducing high bleed-air supply pressure to the level required by pneumatic boots and shutting off flow entirely when de-icing is not needed.