Oil Faults — OIL LO PR (<25 PSI), OIL HI TEMP (>190 °C), FILTER CLOG, the Three Oil Pressures
Oil System covered the circuit and deferred the OIL PRESS/TEMP warning thresholds to here. This article pays that off: OIL LO PR = oil pressure < 25 PSI, OIL HI TEMP = oil temperature > 190 °C, and it separates the three oil-pressure numbers cleanly (so 535 PSI is never mistaken for a warning).
1. The three oil faults
| Fault | Trigger | Handling |
|---|---|---|
| ENG OIL LO PR | oil pressure < 25 PSI | THR LEVER IDLE → (if persists) shut down, LAND ASAP |
| ENG OIL HI TEMP | oil temperature > 190 °C | RR: THR REDUCE to lower oil temp; if persists at idle → MASTER OFF |
| ENG OIL FILTER CLOG | high oil-filter differential (05/10) | crew awareness |
2. OIL LO PR — and the three oil pressures
ENG 1(2) OIL LO PR — ANNUNCIATIONS Triggering Conditions: This alert triggers when the oil pressure is lower than 25 PSI. THR LEVER (AFFECTED ENGINE) ... IDLE ...
Per PRO-ABN-ENG, OIL LO PR triggers when oil pressure is lower than 25 PSI; THR LEVER (affected) → IDLE.
[!warning]- The three oil-pressure numbers, cleanly separated (paying off the 05 debt)
Value Layer Source 0–250 PSI OIL PRESS display scale 10 (DSC-70-90-40) 535 PSI pressure-relief valve hardware setting (pump-downstream ceiling) 05 < 25 PSI low-oil-pressure warning threshold (OIL LO PR) this article (PRO-ABN-ENG) 05 deliberately held that "535 PSI ≠ warning threshold"; here the warning threshold resolves to < 25 PSI. Three numbers, three layers, never to be mixed — 535 PSI is the mechanical relief ceiling, 25 PSI the low-pressure alarm floor.
3. OIL HI TEMP — the RR REDUCE handling
ENG 1(2) OIL HI TEMP — Triggering Conditions: This alert triggers when the engine oil temperature is above 190 °C. For aircraft equipped with RR engines: THR LEVER (AFFECTED ENGINE) ... REDUCE — Gradually reduce thrust on the affected engine in order to decrease oil temperature below the limit. If the caution persists with the thrust lever at idle: ENG MASTER (AFFECTED ENGINE) ... OFF
Per PRO-ABN-ENG, OIL HI TEMP triggers at oil temperature > 190 °C; on RR engines, THR LEVER REDUCE — gradually reduce thrust to bring the oil temperature below the limit; if it persists with the lever at idle, ENG MASTER OFF. RR uses REDUCE (gradual) rather than straight to IDLE — try to cool first, shut down only if that fails.
4. OIL FILTER CLOG
OIL FILTER CLOG (high differential across the oil/scavenge filter, 05's filters on the chip-detector path) is crew awareness — a hint of a developing clog, watch it (PRO-ABN-ENG).
5. Reading and counterintuitive points
| Monitor | Threshold | Meaning |
|---|---|---|
| OIL PRESS | < 25 PSI | low oil pressure (bearing-lubrication risk) → IDLE/shutdown/LAND ASAP |
| OIL TEMP | > 190 °C | high oil temp → RR REDUCE gradually / shutdown |
| OIL QTY | advisory 4 QT | low quantity (05/10) |
| OIL FILTER CLOG | high differential | crew awareness |
[!warning]- 25 PSI (warning) ≠ 535 PSI (hardware relief) ≠ 0–250 PSI (scale) Three oil-pressure numbers, three layers (05/10/this): < 25 PSI low-pressure alarm, 535 PSI mechanical relief ceiling, 0–250 PSI display scale. Don't read 535 as a warning, or 25 as a scale.
[!warning]- RR high-oil-temp handling is "gradual reduce," not straight to IDLE RR OIL HI TEMP: THR LEVER REDUCE, gradually lowering thrust to cool the oil (PRO-ABN-ENG); shut down only if it persists at idle — give cooling a chance first.
Self-test
[!note]- Q1. The OIL LO PR trigger threshold? Oil pressure < 25 PSI.
[!note]- Q2. The OIL HI TEMP trigger, and RR handling? Oil temp > 190 °C; RR: THR LEVER REDUCE to cool, if it persists at idle → MASTER OFF.
[!note]- Q3. What layer is each of 25 / 535 / 0–250 PSI? < 25 PSI = low-pressure warning (this); 535 PSI = hardware relief setting (05); 0–250 PSI = display scale (10). Three layers, never mixed.
[!note]- Q4. The OIL FILTER CLOG level? Crew awareness.
Key takeaways
| Point | Detail |
|---|---|
| OIL LO PR | < 25 PSI; OIL HI TEMP > 190 °C (RR REDUCE gradually); FILTER CLOG crew awareness |
| Three oil pressures | 25 PSI warning / 535 PSI hardware relief / 0–250 PSI scale |
| Low pressure | bearing risk → IDLE/shutdown/LAND ASAP; high temp RR gradual reduce |
References
- FCOM PRO-ABN-ENG — OIL LO PR (< 25 PSI); OIL HI TEMP (> 190 °C, RR THR REDUCE gradual / persists MASTER OFF); OIL FILTER CLOG (crew awareness).
- FCOM (05) / DSC-70-90-40 (10) — 535 PSI hardware relief / 0–250 PSI scale (the three layers).
Independent study material, not an Airbus publication and not endorsed by the manufacturer. Always defer to the current operator FCOM, FCTM, and QRH for operational use.