AM Hydraulic & Pneumatic Systems Flashcards
6 cards from real AM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 AM Hydraulic & Pneumatic Systems flashcards as text
What is the typical operating pressure range for a large transport aircraft hydraulic system?
Answer: 3,000–5,000 psi
Large transport aircraft hydraulic systems typically operate between 3,000 and 5,000 psi, with many modern aircraft using 5,000 psi systems for reduced weight.
What fluid is specified for most Boeing commercial aircraft hydraulic systems?
Answer: Skydrol (phosphate ester)
Boeing commercial aircraft use Skydrol, a fire-resistant phosphate ester hydraulic fluid, to reduce fire risk in the event of a hydraulic leak.
What is the function of a hydraulic accumulator?
Answer: Store pressurized fluid and dampen pressure surges
A hydraulic accumulator stores pressurized fluid under a pre-charged gas pressure to supplement pump output during peak demands and dampen pressure spikes.
Which seal material is NOT compatible with Skydrol hydraulic fluid?
Answer: Buna-N (nitrile) rubber
Nitrile (Buna-N) seals swell and deteriorate rapidly when exposed to Skydrol phosphate ester fluid and must not be used in these systems.
What is the purpose of a hydraulic system relief valve?
Answer: Limit maximum system pressure to protect components
A relief valve opens to return fluid to the reservoir when system pressure exceeds the set maximum, protecting pumps, actuators, and lines from over-pressurization.
How is hydraulic fluid contamination level typically classified in aircraft maintenance?
Answer: By NAS 1638 or ISO 4406 cleanliness codes
NAS 1638 and ISO 4406 cleanliness codes classify hydraulic fluid contamination by counting particle sizes per unit volume using automated particle counters.