IA Fuel Systems & Hydraulic Systems Inspection 2 — Questions and Answers
Question 1: What is the correct method for checking fluid level in an aircraft hydraulic reservoir during an inspection?
- Always check with all actuators in the fully extended position
- Always check with all actuators in the fully retracted position
- Follow the specific aircraft manufacturer's maintenance manual instructions (Correct answer)
- Check only with the aircraft in a level flight attitude
Correct answer: Follow the specific aircraft manufacturer's maintenance manual instructions
The correct position for checking hydraulic fluid level varies significantly by aircraft design and system architecture; the IA must always follow the specific aircraft manufacturer's maintenance manual instructions.
Question 2: A milky or cloudy appearance of hydraulic fluid most commonly indicates which condition?
- Normal aging and oxidation of the fluid
- Water contamination in the hydraulic system (Correct answer)
- Air entrainment from a malfunctioning pump
- Fluid overheating beyond maximum operating temperature
Correct answer: Water contamination in the hydraulic system
A milky or cloudy appearance in hydraulic fluid is a classic indicator of water contamination, which can cause corrosion in the system and degrade the fluid's lubricating and sealing properties.
Question 3: What is the most common cause of hydraulic fluid leaks at line connections during maintenance inspections?
- Improper torque on fittings (Correct answer)
- Vibration fatigue cracks in rigid lines
- Chemical incompatibility between fluid and line materials
- Excessive system operating pressure
Correct answer: Improper torque on fittings
Improperly torqued fittings are the most common source of hydraulic leaks at connections; under-torquing allows seepage while over-torquing distorts seating surfaces and causes cracks.
Question 4: Under what circumstances may MIL-H-5606 (petroleum-based, red) hydraulic fluid be mixed with MIL-H-83282 (synthetic, red) hydraulic fluid?
- They may be mixed in emergencies if the resulting blend does not exceed 25% of either type
- They may be mixed if system operating temperature will not exceed 160°F
- They should never be mixed; the system must be flushed if contamination occurs (Correct answer)
- They are interchangeable and may always be mixed in any proportion
Correct answer: They should never be mixed; the system must be flushed if contamination occurs
Although both fluids are red and may appear identical, MIL-H-5606 and MIL-H-83282 should not be mixed; if contamination occurs, the system must be drained, flushed, and refilled with the aircraft manufacturer's specified fluid.
Question 5: What is the primary function of a hydraulic accumulator in an aircraft hydraulic system?
- To filter particulate contaminants from circulating hydraulic fluid
- To store pressurized fluid for emergency use and dampen pressure surges (Correct answer)
- To boost hydraulic pressure above the pump's rated output
- To provide a vent path for bleeding air from the hydraulic system
Correct answer: To store pressurized fluid for emergency use and dampen pressure surges
Hydraulic accumulators store a quantity of pressurized fluid for emergency operation of critical systems and help absorb pressure surges, providing more consistent system pressure during rapid actuator movement.
Question 6: During an annual inspection, an IA finds hydraulic fluid seeping past the piston rod seal of a landing gear actuator. What action is required?
- Clean the area, log it as a monitoring item, and return to service with owner advisory
- Apply hydraulic sealant to the external seal area and return to service
- Replace the seals or overhaul the actuator before returning to airworthy service (Correct answer)
- Reduce system pressure by 10% and return to service with owner notification
Correct answer: Replace the seals or overhaul the actuator before returning to airworthy service
A leaking actuator seal compromises system pressure integrity and creates a fire hazard from hydraulic fluid on hot components; the actuator must have its seals replaced or be overhauled before the aircraft is returned to service.
Question 7: Which regulation requires the inspection of hydraulic systems as part of an aircraft annual inspection?
- 14 CFR Part 91.207
- 14 CFR Part 43, Appendix D (Correct answer)
- 14 CFR Part 65.82
- 14 CFR Part 23.1435
Correct answer: 14 CFR Part 43, Appendix D
14 CFR Part 43, Appendix D enumerates the items that must be inspected during an annual or 100-hour inspection, including hydraulic systems and their components.
IA Fuel Systems & Hydraulic Systems Inspection 2
What is the correct method for checking fluid level in an aircraft hydraulic reservoir during an inspection?