T6 B OnBoard Oxygen Generation System OBOGS Created

T-6 B On-Board Oxygen Generation System (OBOGS) Created: 5 Sep 2015 Updated: 14 Sep 2019 T 6 BDriver. com

Objectives • Identify components and understand operation of OBOGS (Utilize OBOGS system schematic while reviewing this slideshow)

References • T-6 B NATOPS Manual • Section 1 • On-Board Oxygen Generating System (OBOGS) • • • Oxygen Pressure Regulator Supply Lever Oxygen Pressure Regulator Concentration Lever Oxygen Pressure Regulator Pressure Lever Oxygen Pressure Regulator BIT Button Oxygent Pressure Regulator Flow Indicator

Lt Side P 3 Port Shutoff Valve OBOGS System Overview Heat Exchanger High Temp Switch OBOGS TEMP 200 F Condensation Drain Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 3 min – OBOGS FAIL if internal failure Low Press Switch OBOGS FAIL OBOGS BIT Water Separator (Hot Bat Bus) OBOGS FAIL Monitor Low Concentration Provides each pilot with automatically regulated oxygen supply • Uses conditioned bleed air from engine by pressure swing absorption using a molecular sieve • Oxygen provided at a slight positive pressure • Plenum provides a limited amount of oxygen in case of OBOGS failure • Each cockpit has pressure regulator Internal Failure Pressure Regulator/Shutoff Valve OBOGS FAIL • Concentrator Composition Controller Non-return Valve Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Plenum OXYGEN FLOW BIT SUPPLY • EMERGENCY • NORMAL • TEST MASK Cockpit Specific • NORMAL ON OXYGEN • MAX OFF Affects Both Cockpits < 15 K: 25 – 70% > 15 K: 45 – 95% MAX: 95% Cockpit Specific (Turns on OBOGS & Opens P 3 Shutoff Valve)

Bleed Air Supply Lt Side P 3 Port • Left Side P 3 Port • Tap off compressor section of engine • Supplies engine bleed air to OBOGS only • Shutoff Valve • • Controlled by supply lever on Oxygen Pressure Regulator Allows the flow of bleed air into the OBOGS Accessory Section (right side) Gas Generation Section (left side) Shutoff Valve Supply Lever Lt Side P 3 Port

Lt Side P 3 Port Heat Exchanger Shutoff Valve Heat Exchanger • Cools bleed air for use in OBOGS • Divided into 2 sections: • • Cooling for anti-G/canopy seal/OBOGS (left side) Cooling for all other ECS functions • Air directed to heat exchanger by cooling air inlet duct on nose • On ground, flap covers inlet duct and WOW switch activates blower to push air across heat exchanger Cooling Air Inlet OBOGS Line Heat Exchanger

Supply Line Lt Side P 3 Port • High Temperature Switch • • • Shutoff Valve Heat Exchanger • OBOGS TEMP 200 F Condensation Drain OBOGS FAIL Low Press Switch Condensation Drain • • High Temp Switch • Measures temperature in OBOGS ducting A OBOGS TEMP caution illuminates if temperature exceeds 200°F in OBOGS ducting Indicates heat exchanger not sufficiently cooling bleed air Actually multiple drains in the system (3 total) Removes moisture from lines as a direct result of cooling through heat exchanger Low Pressure Switch • • • Senses bleed air pressure upstream of the OBOGS concentrator An OBOGS FAIL warning illuminates to indicate low bleed air pressure in system OBOGS Fail Message critical action items requires advancing PCL to see if warning extinguishes

OBOGS Unit Lt Side P 3 Port • Located in left avionics bay (and labeled OXYGEN) • Powered by Hot Battery Bus • Activation and functional settings controlled by Oxygen Pressure Regulator (either cockpit) • Extracts oxygen from conditioned bleed air by pressure swing absorption using a molecular sieve • Oxygen stored in Plenum and pushed to pilots at a low positive pressure • Internally: Shutoff Valve Heat Exchanger OBOGS TEMP High Temp Switch 200 F Condensation Drain OBOGS FAIL Low Press Switch OBOGS (Hot Bat Bus) • • OBOGS FAIL Internal Failure • Left Avionics Bay Shutoff Valve Composition Controller Concentrator Monitor An OBOGS FAIL warning illuminates to indicate internal failure of system OBOGS Unit

OBOGS Unit Lt Side P 3 Port • • • Shutoff Valve Heat Exchanger OBOGS TEMP Water Separator • Pressure Regulator/Shutoff Valve • • High Temp Switch Internal system to actively remove water from bleed air Drains water to external vent Controlled by supply lever on regulator Turning supply lever on in either cockpit opens valve and allows oxygen production 200 F Condensation Drain OBOGS FAIL OBOGS Water Separator Pressure Regulator/Shutoff Valve Concentrator • • • Low Press Switch (Hot Bat Bus) OBOGS FAIL • Sets oxygen concentration as selected by concentration lever on regulator Concentration is based on current altitude When concentration levers are in NORMAL: • • BIT OBOGS FAIL • Internal Failure When either concentration lever is in MAX: • • Monitor Low Concentration Concentrator Composition Controller • Non-return Valve • OBOGS Fail Message Summary • • An OBOGS FAIL warning illuminates to indicate: • Low bleed air pressure • Low oxygen concentration • Internal system failure You can only affect the failure due to low pressure by advancing the PCL! • OBOGS supplies highest possible oxygen concentration to both regulators Concentration as low as 55% or as high as 95% oxygen depending on factors (individual concentrator efficiency, bleed air press. , cabin alt, aircrew breathing demands) Maximum concentration light (green) illuminates on regulator Composition Controller • • Oxygen concentration is 25% – 70% for altitudes up to 15, 000 ft MSL Oxygen concentration is 45% - 95% for altitudes above 15, 000 ft MSL Controls the gas composition (mixture) of the product Monitor • • Monitors composition and concentration of air being created An OBOGS FAIL warning illuminates to indicate low oxygen concentration from the system

OBOGS Unit Lt Side P 3 Port • Built-in-Test (BIT) • • • Shutoff Valve Heat Exchanger • OBOGS TEMP High Temp Switch Power up BIT to check system on initial start up System enters a 4 -minute, sensor warm-up period when first activated The OBOGS FAIL warning inhibited during the warm-up period (4 minutes) for concentration & internal failure (still works for low pressure) At end of BIT system will activate OBOGS FAIL warning if internal failure • Warning remains illuminated until failure is cleared by the self-test or by resetting regulators 200 F Condensation Drain OBOGS FAIL Low Press Switch OBOGS (Hot Bat Bus) OBOGS FAIL Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure Water Separator Pressure Regulator/Shutoff Valve • Initiated Built-in-Test (I-BIT) • • • BIT OBOGS FAIL Internal Failure Monitor Low Concentration Concentrator Composition Controller • Non-return Valve Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Use button on regulator to initiated the BIT at times other than the power up BIT Provides verification that OBOGS monitor is working along with fail warning Momentarily pushing button: • Opens valve in concentrator allowing ambient air into the concentration monitor • Concentration drops below normal (20 -30 seconds) • The OBOGS FAIL warning illuminates for low concentration • Once valve closes and concentration returns, warning extinguishes (within 2 minutes) Operations with mask down or loose fitting: • • • May induce OBOGS FAIL warning Ensure mask secure If extended mask down operation is desired, place respective OBOGS supply lever to OFF

OBOGS Unit Lt Side P 3 Port • Provides a limited supply of oxygen in the event OBOGS fails • Duration of Plenum depends on: Shutoff Valve • • Heat Exchanger OBOGS TEMP High Temp Switch 200 F Condensation Drain OBOGS FAIL Low Press Switch OBOGS Water Separator (Hot Bat Bus) OBOGS FAIL Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure Pressure Regulator/Shutoff Valve BIT OBOGS FAIL Internal Failure Monitor Low Concentration Concentrator Composition Controller Non-return Valve Plenum Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Cockpit pressurization Aircraft pressure altitude Pilot regulator settings Pilot demand

Pressure Regulator Lt Side P 3 Port • Panel-mounted regulator on right side console of each cockpit • Controls OBOGS electrical power and oxygen flow for respective cockpit • Can be “gang-loaded” in event of hypoxia symptoms or loss of cabin pressure (ON/MAX/EMERGENCY) Shutoff Valve Heat Exchanger OBOGS TEMP High Temp Switch 200 F Condensation Drain OBOGS FAIL Low Press Switch OBOGS BIT Water Separator (Hot Bat Bus) OBOGS FAIL Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure OBOGS FAIL Internal Failure Pressure Regulator/Shutoff Valve Monitor Low Concentration Concentrator Composition Controller Non-return Valve Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Plenum OXYGEN FLOW • EMERGENCY • NORMAL • TEST MASK BIT SUPPLY • NORMAL ON OXYGEN • MAX OFF Oxygen Pressure Regulator (front cockpit)

Pressure Regulator Lt Side P 3 Port • Supply Lever • • Shutoff Valve • • Heat Exchanger • OFF • • High Temp Switch OBOGS TEMP Controls power to OBOGS & oxygen flow to respective regulator ON Opens P 3 Shutoff Valve (left side) Opens Regulator Shutoff Valve (internally) for respective regulator Cuts OBOGS power & oxygen flow to respective regulator Both regulator supply levers must be OFF to disable the OBOGS system 200 F Condensation Drain Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure Low Press Switch OBOGS FAIL OBOGS Internal Failure Concentrator Composition Controller Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min OXYGEN FLOW BIT • Oxygen concentration is 25% – 70% for altitudes up to 15, 000 ft MSL Oxygen concentration is 45% - 95% for altitudes above 15, 000 ft MSL When either concentration lever is in MAX: OBOGS supplies highest possible oxygen concentration to both regulators Concentration as low as 55% or as high as 95% oxygen depending on factors (individual concentrator efficiency, bleed air press. , cabin alt, aircrew breathing demands) Maximum concentration light (green) illuminates on regulator BIT Button Flow Indicator SUPPLY • EMERGENCY • NORMAL • TEST MASK Cockpit Specific • • • Non-return Valve Plenum Sets oxygen concentration Concentration is based on current altitude When concentration levers are in NORMAL: • • Monitor Low Concentration • • • OBOGS FAIL Pressure Regulator/Shutoff Valve OBOGS FAIL Concentration Lever BIT Water Separator (Hot Bat Bus) • • NORMAL ON OXYGEN • MAX OFF Affects Both Cockpits < 15 K: 25 – 70% > 15 K: 45 – 95% MAX: 45 – 95% Cockpit Specific (Turns on OBOGS & Opens P 3 Shutoff Valve) Pressure Lever Concentration Lever Supply Lever

Pressure Regulator Lt Side P 3 Port • Pressure Lever • • • Shutoff Valve Heat Exchanger • BIT Button • High Temp Switch OBOGS TEMP EMERGENCY – Provides pilot with positive pressure oxygen flow needed during emergencies NORMAL – Provides a slight positive pressure of oxygen flow TEST MASK – Provides highly pressurized flow to check face-to-mask seal Pressing momentarily activates an I-BIT 200 F Condensation Drain Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure Low Press Switch OBOGS FAIL OBOGS • • • Provides visual indication of oxygen flow through regulator Each inward breath activates a flow indicator (white) Can indicate leak in mask or hose assembly OBOGS FAIL Internal Failure Pressure Regulator/Shutoff Valve OBOGS FAIL Flow Indicator BIT Water Separator (Hot Bat Bus) • Monitor Low Concentration Concentrator Composition Controller Non-return Valve Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Plenum OXYGEN FLOW BIT Flow Indicator SUPPLY • EMERGENCY • NORMAL • TEST MASK Cockpit Specific BIT Button • NORMAL ON OXYGEN • MAX OFF Affects Both Cockpits < 15 K: 25 – 70% > 15 K: 45 – 95% MAX: 45 – 95% Cockpit Specific (Turns on OBOGS & Opens P 3 Shutoff Valve) Pressure Lever Concentration Lever Supply Lever

Pressure Regulator Lt Side P 3 Port • • Shutoff Valve Heat Exchanger • • • High Temp Switch OBOGS TEMP 3 Anti-Suffocation Valves (ASV) One in oxygen regulator (low resistance) • After engine start and OBOGS powered on, held closed during normal operations to prevent mixing of cabin and OBOGS air supply One at base of main oxygen supply hose (high resistance) One in CRU-60/P connector ASVs ensure pilot can breathe in event OBOGS fails 200 F Condensation Drain Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure Low Press Switch OBOGS FAIL OBOGS BIT Water Separator (Hot Bat Bus) OBOGS FAIL Internal Failure Pressure Regulator/Shutoff Valve OBOGS FAIL Monitor Low Concentration Concentrator Composition Controller Non-return Valve Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Plenum OXYGEN FLOW BIT SUPPLY • EMERGENCY • NORMAL • TEST MASK Cockpit Specific • NORMAL ON OXYGEN • MAX OFF Affects Both Cockpits < 15 K: 25 – 70% > 15 K: 45 – 95% MAX: 45 – 95% Cockpit Specific (Turns on OBOGS & Opens P 3 Shutoff Valve) Anti-Suffocation Valves

Lt Side P 3 Port Shutoff Valve Conclusion Heat Exchanger • High Temp Switch OBOGS TEMP Identified components and described operations of OBOGS 200 F Condensation Drain Built In Test (BIT) -Initiated upon first activation of system -Sensor warm-up period of 4 min -OBOGS FAIL inhibited (by Monitor for concentration) -OBOGS FAIL still works for Low Pressure -At end of 4 min – OBOGS FAIL if internal failure Low Press Switch OBOGS FAIL OBOGS BIT Water Separator (Hot Bat Bus) OBOGS FAIL Internal Failure Pressure Regulator/Shutoff Valve OBOGS FAIL Monitor Low Concentration Concentrator Composition Controller Non-return Valve Initiated Built In Test (I-BIT) -Initiated by BIT on regulator after 4 min warm-up -Verification that OBOGS sensor & OBOGS FAIL work -Use: --Momentarily push button --Oxy concentration purposely drops --Get OBOGS FAIL from Monitor (for concentration) --Warning extinguishes within 2 min Plenum OXYGEN FLOW BIT SUPPLY • EMERGENCY • NORMAL • TEST MASK Cockpit Specific • NORMAL ON OXYGEN • MAX OFF Affects Both Cockpits < 15 K: 25 – 70% > 15 K: 45 – 95% MAX: 45 – 95% Cockpit Specific (Turns on OBOGS & Opens P 3 Shutoff Valve) Abnormal OBOGS Scenarios located in Procedures Section/EPs