Engine Oil/Anti-Ice Flashcards
Engine Oil System Type
Self-contained, pressurized, recirculating dry-sump system
Oil Flow
Pump sucks up oil and pressurizes oil as it flows through filter into passages in AGB and six main sump bearings.
2 sets of jets provide each main bearing lubrication providing redundancy following malfunction or damage.
Scavenge pump sucks up oil and sends past chip detector, fuel/oil cooler, main frame, scroll vanes and back to oil tank.
Oil Filter
Impending bypass PDI has thermal lockout below 38*C to prevent indicator from popping during cold-weather starting.
Oil Cooler
Scavenge oil cooled by fuel/oil cooler on forward face of AGB
Then flows through the scroll vanes that function as air/oil cooler, cooling oil and providing full-time anti-icing.
Oil Temp/Press
Sensors on forward face of AGB; cautions activated by vertical instruments
Engine Start System
Pneumatic start using air turbine engine starter–either APU or engine crossbleed air.
When started pressed, air from selected source directed through start valve to engine starter.
Anti-ice/start bleed valve remains open to reduce backpressure and prevent compressor stall until Ng reaches approx 90-94% OAT dependent.
Dropout 52-65% Ng–if needed disengage by pulling on PCL, cb or removing air source
APU Start
APU provides pneumatic power for start regardless of AIR SOURCE ECS/START switch position
Crossbleed Start
Pressing starter simultaneously opens start valve on receiving engine and crossbleed valve on donor engine.
Ng shall be a min of 24% prior to advancing PCL to IDLE; requires donor engine Ng of approx 90-94%
Anti-Ice System Methods
- Vent bleed air into engine swirl vanes and engine Inlet Guide Vanes by engine anti-ice/start bleed valve.
- Vent bleed air into airframe engine inlet by engine inlet anti-ice valve.
- Continuously pump oil through scroll vanes.
Both valves held closed electrically and controlled by ENGINE ANTI-ICE and DEICE MASTER switches. When DEICE MASTER is ON, both valves controlled by ice detector.
Engine Anti-Ice/Start Bleed Valve and VG Interaction
Valve provides 5th stage bleed air and opens during starts. Open below 90% to prevent compressor instability.
Temporary hang up of the Variable Geometry system at valve may cause engine flameouts at low collective settings.
VG activated by fuel pressure from HMU; HMU will schedule max fuel flow to VG actuator creating diversion from scheduled fuel flow to engine. At low fuel flow regimes, can cause flameout.
Malfunctiong Anti-Ice/Start Bleed Valve
- Illum of ENG ANTI-ICE ON advisory above 90 (above 94% Ng if OAT >15*C)
- No illum when Ng drops below approx 88% (may vary on sliding scale)
- No illum when switch selected ON
- No rise in TGT when switch selected ON (30-100*C)
NOTE With ENG ANTI-ICE ON, max torque available is reduced up to 18% per engine.
Inlet Anti-Ice Valve
Bleed air routed from compressor through valve to inlet cowling and fairing.
No1 or No2 INLET ANTI-ICE advisory illuminates when air heats engine inlet to approx 93C; full anti-ice capability may not be available above 4C and will not be available above 13*C
With ENGINE ANTI-ICE switches ON, valve opened variably based on OAT; with ENGINE ANTI-ICE switches OFF and DEICE MASTER switch ON and ice detected, open variably based on OAT.
Release of 5th stage bleed air controlled by freon filled bellows which react only to temp:\
- <4*C - open
- 4-13C - bellows begin closing above 4C
- > 13*C - valve closed
WARNING Illumination of INLET ANTI-ICE ON light when OAT is above 13*C is indication of faulty engine inlet anti-ice modulating valve. The resultant loss of power could be a max of 49% when engine anti-ice system is activated.
Oil Anti-Ice
Primary function to cool hot engine oil providing anti-icing of mainframe. Air heated by scroll vanes vented overboard through the IPS and does not provide anti-icing protection to air entering compressor.
