Hydraulic and Pneumatic Systems Flashcards
6 cards from real A&P practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Hydraulic and Pneumatic Systems flashcards as text
What is the correct method for connecting a B-nut (flared tube fitting) on an aircraft hydraulic line?
Answer: Align the flare with the fitting, thread the nut by hand to ensure no cross-threading, then torque to specification
B-nut (AN/MS flared) fittings must be hand-started to prevent cross-threading, then torqued to the value specified by the fitting size per AC 43.13-1B.
Which FAA document specifies acceptable torque values for standard aircraft AN flared tube fittings?
Answer: AC 43.13-1B, Chapter 9
AC 43.13-1B (Acceptable Methods, Techniques, and Practices — Aircraft Inspection and Repair), Chapter 9, provides torque values for flared tube fittings.
What is cavitation in an aircraft hydraulic pump, and what causes it?
Answer: Vapor bubble formation and collapse inside the pump caused by inadequate inlet pressure or restricted suction
Cavitation occurs when low inlet pressure causes the hydraulic fluid to vaporize, forming bubbles that collapse violently inside the pump, causing noise, vibration, and rapid pump damage.
What does the term 'bootstrap' mean in reference to an aircraft hydraulic system?
Answer: A system where the fluid reservoir is pressurized by system pressure to ensure positive pump inlet pressure
A bootstrap reservoir uses a piston pressurized by system pressure (from the return line) to maintain positive fluid pressure at the pump inlet, preventing cavitation at altitude.
When inspecting a hydraulic hose assembly, which condition requires immediate replacement?
Answer: A kink that prevents free flex of the hose
A kinked hydraulic hose must be replaced because the kink damages the internal reinforcement layers, creating a weak point that can fail under pressure.
What is the maximum allowable bend radius rule for flexible hydraulic hoses during installation?
Answer: Never bend tighter than the minimum bend radius specified by the hose manufacturer
Flexible hoses must never be bent tighter than the manufacturer-specified minimum bend radius, as over-bending damages internal layers and reduces rated burst pressure.