FAA Aviation Mechanic Powerplant (AMP)Engine InspectionHard
A technician sends a routine oil sample from a turbine engine for Spectrometric Oil Analysis Program (SOAP) testing. The report shows iron content has increased from 5 ppm to 45 ppm over the last three sampling intervals, while other elements remain stable. What is the most appropriate interpretation and action?
- AThe result indicates the wrong oil was used and the system must be flushed
- BThis is a normal trend and requires no action since iron is always present in oil
- CThe trending increase in iron suggests developing wear in a steel component; further investigation such as borescope or filter inspection is warranted
- DSOAP results cannot detect trends over time, only single-sample abnormalities
Show answer & explanationAnswer & explanation
Correct answer: C. The trending increase in iron suggests developing wear in a steel component; further investigation such as borescope or filter inspection is warranted
SOAP analysis tracks trace metal concentrations over successive oil samples. A significant upward trend in a specific element, such as iron, indicates increasing wear of a ferrous component and warrants further investigation, even if the absolute value alone might not be alarming at a single point in time.
Why the other options are wrong
- A. Wrong oil type would typically show broader chemical anomalies, not an isolated trending metal increase.
- B. A sharp upward trend, even in normally present elements, is a warning sign, not normal.
- D. SOAP is specifically valuable for trend analysis across multiple samples over time.
Spectrometric Oil Analysis Program (SOAP)
A trend-monitoring program that measures trace metal concentrations in oil samples to detect developing engine component wear before failure.
- Tracks parts-per-million levels of metals like iron, copper, aluminum, silver
- Trend analysis over multiple samples is more meaningful than a single reading
- Sudden or steady increases in specific metals suggest wear in components made of that material
Memory trick: 'Rising metal levels are the oil telling on a wearing part'