DOC AIRBUS | AMM A320FOIL FILTER CLOGGING WARNING SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. Oil Differential Pressure Switch
** ON A/C NOT FOR ALL - The oil differential pressure switch is located above the scavenge filter. Lines are routed to the switch from bosses on the scavenge filter.
- Actuation of the differential pressure switch is at:
25.5 psid (1.76 bar) plus or minus 1 psid (0.07 bar) increasing pressure
22 psid (1.52 bar) decreasing pressure.
2. Oil Filter Clogging Indication
An oil differential pressure switch (also named clogging indicator transmitter) is installed on the lubrication unit. The pressure switch signal is used by the ECAM system to generate the main oil filter clog indication when the oil differential pressure across this filter is comprised between 29 psig (2 bar) and 33 psig (2.28 bar).
In result:
** ON A/C NOT FOR ALL An oil differential pressure switch (also named clogging indicator transmitter) is installed on the lubrication unit. The pressure switch signal is used by the ECAM system to generate the main oil filter clog indication when the oil differential pressure across this filter is comprised between 29 psig (2 bar) and 33 psig (2.28 bar).
In result:
- ENG page on the lower display unit of the ECAM appears with OIL FILTER CLOG indication (White and Amber)
- instructions appear on the upper display unit
3. Engine-mounted visual indication system, associated with the master magnetic
chip detector (MCD)
chip detector (MCD)
A. General
The oil (scavenge) system is equipped with a fan inlet case-installed visual indication system which serves to directly see and check if the oil system is contamined by magnetic particles/chips, or not.
A pop-out type visual indicator, installed just above the oil tank, permits this visual check, each time the nacelle access door to the oil tank is opened during normal line maintenance (oil tank servicing for example)
The oil (scavenge) system is equipped with a fan inlet case-installed visual indication system which serves to directly see and check if the oil system is contamined by magnetic particles/chips, or not.
A pop-out type visual indicator, installed just above the oil tank, permits this visual check, each time the nacelle access door to the oil tank is opened during normal line maintenance (oil tank servicing for example)
B. Description
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL
From front to rear, the visual indication system consists of the items which follow:
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL - the hand-removable probe of the master magnetic chip detector (MCD)
- a two-wire, shielded electrical cable (DPM cable)
- a pop-out type visual indicator
In this system, the electronic circuitry of the visual indicator is supplied by a dedicated (28 VDC; 1.1 Amp. max.) aircraft line, but the visual indication is local, without redundancy in the cockpit.
Besides, the only purpose of the two-wire cable (DPM) is to link (electrically) the MCD hand-removable probe and the pop-out type visual indicator.
C. Operation
The on-engine-installed magnetic particles contamination indicating system is electrically and electronically designed so that the 28 VDC detecting loop made of:
The on-engine-installed magnetic particles contamination indicating system is electrically and electronically designed so that the 28 VDC detecting loop made of:
- the 2 magnets of the MCD hand-removable probe
- the two-wire DPM cable
- the electronics circuitry of the visual indicator
is OPEN as long as the gap between the 2 magnets is not bridged by magnetic particles.
In this condition, or state, the (red) pop-out indicator remains sunk under and inside its transparent cap and is thus NOT VISIBLE (see state 1)
If a magnetic particle contamination occurs in the engine oil system, the gap between the 2 magnets is bridged by the particles and becomes conductive; this closes the 28 VDC loop and energizes (0.5 second only) the electronics of the visual indicator, which in turn energizes (see state 2)
a solenoid which triggers out, or set off, the red pop-out indicator which is then VISIBLE through its transparent cap.
In this state, the 28 VDC aircraft supply is cut-off on the electronics and the solenoid. The pop-out indicator will remain in its set-off, or popped-out position (see state 3), as long as it is not re-armed or re-set manually.
But before resetting it in its ready-to-detect configuration (state 1), it is necessary to: - remove the hand-removable probe; collect the particles on the magnets, and investigate the origin/cause of the magnetic contamination
- get the cause(s) corrected
- clean the probe magnets carefully and re-install it on the lubrication unit.