Engine Instruments Flashcards
What is the purpose of engine instruments?
Necessary for the flight crew to properly adjust and monitor engine system operations and for troubleshooting
Engine instruments must be mounted in a way that is resistive to what type of vibrations?
High
Amplitude
Low
Frequency
What are transient markings?
A diamond, dot, triangle, or a second red radial line, that indicate the absolute max limit
What does a slippage mark look like?
A white radial line starting on the instrument case and extending to the face of the glass
When is a slippage mark used?
Must be present when range markings are on the glass
What do slippage marks do?
Show if the glass has loosened or moved
What do bourdon tubes measure?
High pressure or Temperature
What are 3 examples of high pressure systems?
Hydraulic
Oil
Oxygen
Pressure is directly affected by what?
Temperature
What are diaphragms used to measure?
Low pressure
Has high sensitivity
What do bellows measure?
Low pressure
Has a greater range of movement
What FAR talks about tachometers being a primary engine instrument?
FAR 91.205(b)(4)
What do tachometers measure on reciprocating engines?
Crankshaft RPM
What do tachometers measure on helicopters and turbines?
Rotor or propeller RPM
For turbine engines, the tachometer will indicate in:
Percent of RPM
What is the most common type of mechanical tachometer?
Magnetic Drag Cup
What is the electric tachometer called that is engine driven and produces a three phase AC current at differing frequencies with different speeds?
Tach Generator
(Higher engine RPM = Higher frequency)
The tach generator produces a three phase variable frequency signal that drives what?
A synchronous motor inside the instrument
What type of electric motor is commonly used in electric tachometers?
Synchronous motor
The indicator of a tachometer system is responsive to changes in?
Frequency
Why do helicopters require a minimum of two synchronous tachometer systems?
One indicates engine RPM and the other for the main rotor RPM
What unit in an electric type tachometer system sends information to the indicator?
The three phase AC tach generator
An electric tachometer uses a synchronous motor which is governed by the tach generator’s:
Frequency
In what units are turbine engine tachometers calibrated?
Percent of engine RPM