Aviation Pneumatic Systems

PNEUMATIC SYSTEMS

PNEUMATIC SYSTEM

The learning objective of this presentation, To develop the student's knowledge of the vacuum system to meet the basic functions in vacuum system that supply essential instruments of the aircraft and ability to detect abnormal or unsafe operation and responding to a vacuum system failure

PNEUMATIC SYSTEM

•Aircraft Pneumatic System Intro •Vacuum Systems•Pneumatic Use in Small Aircraft •Pneumatic System Components•Air Pumps •Pneumatic System Operation •Actions before every flight •Failure Causes •Early Recognition •Emergency Procedures •Spatial Disorientation •Redundancy Options

Aircraft Pneumatic System Intro

Sometimes called vacuum pressure systems

Aircraft Pneumatic Systems power Instruments, *landing gear, *flaps, air conditioning, windows, doors and more

In light Aircraft, Suction Pressure Gauge shows Vacuum System Pressure

Vacuum Systems

•Pumps

•Relief Valves •Vacuum Air Filter

•Suction Gauge Gyro instruments:

-Attitude Indicator

-Heading Indicator

Pneumatics Use in Small Aircraft

• Gyro compass

• Artificial Horizon

• Turn coordinator

Pneumatic System Components•Air Pump •Vacuum Regulator •Inlet Air Filter •Overboard Vent Line

•Gauges:

– Attitude Indicator– Heading Indicator

•System Indicators

– Suction Gauge – Gyro Flag

– Annunciator Lights

Pneumatic System Components

• Pneumatic Air Filter

- Prevent system contamination

- Remove air particulates

- Clean air is essential to good operation

Pneumatic System Components

• Pneumatic Pressure Regulator

- Prevents System over pressurization

- Insures proper calibration

Air Pump

Heart of pneumatic system is pressure or vacuum air pump(Usually engine driven)• Two basic types :•Wet air pumps use engine oil to lubricate pump internally

•Dry air pumps - more common –have graphite vanes inside pump casing - self-lubricate as pump rotates

Pneumatic System Operation •Filtered Air is pulled through system by vacuum pump

•Evacuated air passes through instrument case causes gyro to spin

•Spinning gyros provide

“rigidity in space” for instrument references

•Air exhausts through Gyro Pressure Gauge exhaust port

– Gauge measures system pressure

•Failure Warning Systems

Actions Before Every Flight

Check for external damage

Check for loose fittings that allow contaminants into the system

Check the hose And clamps for Oil leaks

Check for oil leaks

Failure Causes • System Contamination

-Solid particles in pneumatic system damage pump and plug valve openings

–Liquids from oil, water, or engine cleaning solvents

• Restriction/ leaks within the system -A loose fitting or damaged hoses-Worn out, misused, or incorrectly routed hoses

• Sudden changes in engine speed- Abrupt engine deceleration- Sudden engine stoppage

Early Recognition

• Pneumatic System health can be determined by the indications on either the vacuum gauge or flags on the attitude indicator

Early Recognition

Inaccurate/conflicting Instrument information

Suction/pressure gauge indicates outside normal operating (green) range

Spotting pneumatic system failure early reduces chances of spatial disorientation

Statistics

1995-2004 Accidents cause by vacuum

Failure

1st Qtr2nd Qtr

95% are Fatal

5% non Fatal

While pneumatic system failures alone do not cause accidents, spatial disorientation does, and tragically these accidents are almost always fatal

Spatial Disorientation Accidents byPilot Certificate and Weather Conditions

Emergency Procedures• Activate a back up power supply for pneumatics

( aux Vacuum pump if have)

• Maintain partial panel instrument flying - Cover up or simulate loss of flight instruments

• Make timed turns

• Notify ATC

• In IMC –seek and fly VMC

Spatial Disorientation When your instruments disagree ,confusion ,dizziness, and uncertainly can cause loss of control. Spatial disorientation occurs quickly when outside visual reference is poor such as night, IMC , Haze

Redundancy Options

Electrical Power Instruments

Secondary Air pump ( Electric Aux Vacuum Pump)

Pressure differential Switch

Conclusion

Pneumatic Systems fail at unexpected times

The danger , in the event of pneumatic system failure is spatial disorientation

Have a good knowledge what power systems on the aircraft you fly

Practice on the partial panel Flying and be familiar with aircraft instruments

Whether you rent , own ,or operate become familiar with the maintenance history of the Aircraft

Summarizing

-Aircraft Pneumatic System Intro -Vacuum Systems-Pneumatic Use in Small Aircraft

-Pneumatic System Components -Air filter -Regulator

-Air Pumps -Pneumatic System Operation -Actions before every flight -Failure Causes -Early Recognition-Statistics -Emergency Procedures -Spatial Disorientation -Redundancy Options -Conclusion

QUESTIONS ?