Engine Oil Analysis

Questions and Answers

What is the implication of finding metallic chips or flakes in the engine?

Presence of small fuzzy particles

Normal engine wear

Oil leakage prevention

Serious internal wear that must be investigated (correct)

Where are MCDs normally located?

Fuel pumps and oil pumps

Engine forward-bearing sump, engine rear-bearing sump, accessory gearbox, and transfer gearbox (correct)

Cylinder heads and valve trains

Engine crankshaft and camshaft

What happens when an MCD is removed?

It opens a valve to allow oil flow

It activates an electric circuit

It closes off a valve to prevent oil leakage (correct)

It triggers an indicator light in the cockpit

What is the purpose of an indicating chip detector?

To detect metallic debris and trigger a warning light Signup and view all the answers

What is the response required from the flight crew when the indicator light illuminates?

To respond to the warning and take necessary precautions to prevent engine damage and ensure flight safety Signup and view all the answers

What type of attachment is commonly used for chip detectors?

Quick-disconnect bayonet fitting Signup and view all the answers

What is the purpose of the fuel pressure differential switch in the fuel system?

To detect the presence of icing on the fuel filter Signup and view all the answers

What happens if too much fuel is supplied to the combustion chamber?

All of the above Signup and view all the answers

What is the function of the fuel control unit in a gas turbine engine?

To control the power output Signup and view all the answers

What is a common issue that can occur in the fuel system due to icing on the fuel filter?

Fuel filter blockage Signup and view all the answers

What is the purpose of the micron filter in the fuel system?

To remove fine contaminants Signup and view all the answers

What is a rich blowout in a gas turbine engine?

A mixture that is too rich to burn Signup and view all the answers

What takes a pressure reading from near the fuel flow transmitter and from between the fuel filter and HP pump?

Fuel pressure differential switch Signup and view all the answers

What is the consequence of compressor surge or stall in a gas turbine engine?

Back-pressure from the combustion chambers Signup and view all the answers

What is the primary purpose of the pneumatic anti-ice system?

To provide surface heating of the engine and/or power plant Signup and view all the answers

Which parts of the engine may require protection from ice formation?

First-stage inlet guide vanes and inlet cowling Signup and view all the answers

What is the source of hot air for the anti-icing system?

HP compressor Signup and view all the answers

What happens when the anti-ice switch is actuated?

A light illuminates in the cockpit and a slight rise in exhaust gas temperature and rpm are noticed Signup and view all the answers

What controls the amount of airflow in the anti-icing system?

Bimetallic spring coils Signup and view all the answers

What is the purpose of engine anti-icing?

To eliminate the formation of ice in the intake Signup and view all the answers

What is the primary purpose of the turbine engine pressure gauge in the oil system?

To indicate actual pressure delivered to the engine Signup and view all the answers

Where is the oil temperature sensor located in relation to the engine bearings?

Before the oil goes to the engine bearings Signup and view all the answers

What happens to the low oil pressure warning light when the engine is starting?

It extinguishes when oil pressure exceeds the low limit Signup and view all the answers

Which component is used for measuring oil pressure in gas turbine engines?

Oil pressure gauge Signup and view all the answers

What type of display systems are commonly used for engine oil indication and warning in modern aircraft cockpits?

ECAM and EICAS displays Signup and view all the answers

What is the function of the low-pressure warning light in an aircraft engine's oil system?

To warn of inadequate oil pressure during engine operation Signup and view all the answers

What does the oil filter differential pressure switch monitor in the oil system?

Pressure differential across the oil filter Signup and view all the answers

What does the oil quantity indicator measure in the lubricating system?

The total volume of oil in the system Signup and view all the answers

What is the primary power source for the EEC during normal engine operation?

Engine-driven permanent magnet alternator (PMA) Signup and view all the answers

What does the EEC primarily control in a turbofan engine?

Fuel flow to the engine Signup and view all the answers

Which statement about the FADEC system is true?

It operates with a dual-channel electronic control unit. Signup and view all the answers

How does the PMA contribute to the operation of the EEC?

It supplies electric power for the EEC's functioning. Signup and view all the answers

Where is the EEC typically mounted in a large turbofan engine?

On the fan casing Signup and view all the answers

What is the primary function of the fuel metering valve in relation to the EEC?

To react to commands from the EEC Signup and view all the answers

What type of cooling method is used for the EEC?

Natural fan case cooling air Signup and view all the answers

What is a characteristic feature of a true FADEC system?

It lacks a backup hydromechanical fuel control system Signup and view all the answers

Study Notes

Engine Wear and Chip Detection

Small fuzzy particles or grey metallic paste indicate normal engine wear; not concerning.
Metallic chips or flakes suggest serious internal wear that needs further investigation.
MCD (magnetic chip detector) locations: engine forward-bearing sump, rear-bearing sump, accessory gearbox, transfer gearbox.
MCDs are labeled by their scavenge system affiliation and prevent oil leakage when removed.
A common MCD feature is a quick-disconnect bayonet fitting.
Some MCDs have an electric circuit that activates a warning light in the cockpit via an indicating chip detector.

Oil System Indication

Oil pressure, quantity, low pressure, filter differential, and temperature indicators are essential components of engine oil systems.
The turbine engine pressure gauge connects downstream of the main oil filter for accurate pressure readings.
Low oil pressure warning lights activate with aircraft electrical power when the engine is off; should extinguish upon engine start and pressure rise.
Oil temperature sensors are positioned in the pressure line before reaching engine bearings after oil system components.

Engine Oil Indication Systems

Modern aircraft display engine oil indications and warnings electronically via ECAM (Electronic Centralized Aircraft Monitor) or EICAS (Engine Indication and Crew Alerting System).

Fuel Filters

Three common filter types: micron filter, wafer screen filter, and plain screen mesh filter, each dictated by specific filtering needs.

Fuel Pressure Differential Switch

Detects icing on fuel filters by monitoring pressure differential; illuminates cockpit warning light if a set threshold is reached.
Takes pressure readings near the fuel flow transmitter and between the fuel filter and high-pressure pump to indicate blockages.

Fuel Control Systems

Fuel Control Units regulate power/thrust by controlling fuel quantity injected into the combustion chamber.
Excess fuel can cause turbine damage, compressor stall, or rich blowout conditions.
Electric power for Fuel Electronic Control (EEC) functions derived from aircraft systems; basic operation powered by a separate engine-driven permanent magnet alternator (PMA).

Full Authority Digital Engine Control (FADEC)

FADEC system employed in modern high-bypass turbofan engines with dual-channel EEC for comprehensive engine operation control.
The EEC processes engine data from various electronic sensors to determine fuel flow needs.
Power supplied to EEC from PMA or aircraft electrical systems; PMA has dual coils for independent channel power.

Anti-Icing System

Pneumatic anti-ice systems heat engine surfaces to prevent ice formation in critical areas like inlet guide vanes and nose cone.
Hot air sourced from the high-pressure compressor, regulated through valves, directed to areas needing anti-icing.
Activation of anti-ice switches causes cockpit warning lights to illuminate and observable rises in exhaust gas temperature and engine RPM.
Bimetallic spring coils in air regulator valves control airflow based on air temperature for efficient anti-icing management.

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Description

Learn to identify signs of engine wear through oil analysis. Understand the difference between normal engine wear and serious internal wear. Identify locations of Magnetic Chip Detectors (MCD) in an engine.