FAA Aviation Mechanic Airframe (AMA)Hydraulic and Pneumatic SystemsMedium
A technician is comparing two hydraulic filter elements removed from a system for inspection. One is made of pleated paper and is designed to be discarded once contaminated; the other is made of fine stainless steel wire mesh and can be cleaned ultrasonically and reused. These two element types are best described, respectively, as:
- APrimary and secondary filters
- BMicronic (disposable) and cleanable (wire mesh) elements
- CFull-flow and bypass elements
- DCase drain and pressure filters
Show answer & explanationAnswer & explanation
Correct answer: B. Micronic (disposable) and cleanable (wire mesh) elements
Micronic filter elements are made of treated paper or fiber material with very fine pore sizes and must be replaced (they cannot be effectively cleaned). Wire mesh (cleanable) elements have larger, more uniform openings, are more durable, and can be disassembled and cleaned for reuse, though they typically offer less fine filtration than micronic elements.
Why the other options are wrong
- A. Primary and secondary are not standard terms distinguishing these element types.
- C. Full-flow and bypass describe filter circuit arrangement, not element material/type.
- D. Case drain and pressure filters describe filter location in the system, not construction type.
Hydraulic Filter Element Types
Hydraulic filter elements are generally either disposable micronic (paper/fiber, fine filtration, replace only) or cleanable wire mesh (metal, reusable, coarser filtration).
- Micronic elements offer finer filtration but cannot be cleaned
- Wire mesh elements are durable and can be ultrasonically cleaned
- Element choice affects both contamination control and maintenance cost
Memory trick: Paper is 'pitched' (disposable); mesh is 'mended' (cleanable)