FAA Aviation Mechanic Powerplant (AMP)Reciprocating EnginesMedium
During a scheduled inspection program, a technician submits an engine oil sample for spectrometric oil analysis (SOAP). The most recent report shows a sharp increase in iron and chromium content compared to previous samples, while other elements remain stable. This trend most likely indicates:
- ANormal seasonal variation in oil additive breakdown
- BDepletion of the anti-wear additive package in the oil, requiring an oil change only
- CContamination from an external source such as improperly cleaned oil sampling equipment
- DIncreasing wear of ferrous engine components such as steel cylinder walls, rings, or bearings
Show answer & explanationAnswer & explanation
Correct answer: D. Increasing wear of ferrous engine components such as steel cylinder walls, rings, or bearings
Spectrometric oil analysis identifies trace metal content in used oil to detect abnormal wear trends. Iron and chromium are associated with steel and chrome-plated components such as cylinder walls, piston rings, and bearings; a sharp increase in these elements signals increasing wear of ferrous parts that warrants further investigation.
Why the other options are wrong
- A. A sharp spike in specific wear metals is not normal seasonal variation; it should be investigated.
- B. Additive depletion would show in additive elements, not specifically iron and chromium wear metal spikes.
- C. While contamination is possible, a consistent trend across multiple samples points to actual component wear, not sampling error.
Spectrometric Oil Analysis Program (SOAP)
A trend-monitoring program that analyzes trace metal content in used engine oil samples to detect abnormal component wear before failure occurs.
- Iron/chromium indicate steel or chrome-plated part wear
- Copper/silver often indicate bearing or bushing wear
- Trends over multiple samples are more meaningful than a single reading
Memory trick: Metal in the oil is a message — iron spikes whisper 'something's wearing away!'