Engine Instrumentation Questions and Answers

Answer: A

Correct answer: Both Statement I and Statement II are correct

Both are true and the second gives the main reason. A direct reading gauge brings the fluid itself into the cockpit through a pipe, so a fractured line puts hot oil or fuel behind the instrument panel - a leak and fire hazard directly in front of the crew.

A remote system leaves the sensor at the engine and carries only an electrical signal forward. It brings two further advantages: no long capillary to introduce lag or to break, and a signal that can be recorded, processed and shown on a shared display alongside other parameters.

Answer: B

Correct answer: Both Statement I and Statement II are correct

Both are true and the second explains the first. Individual engines of the same type run at different baseline vibration levels, because of manufacturing tolerances, balance history and installation, so an absolute figure carries little information on its own.

What signifies is change: a steady rise over successive flights with nothing else altered points to a developing imbalance - blade damage, a shifted balance weight or bearing wear. Engine condition monitoring is therefore built on trends in vibration, exhaust temperature and fuel flow rather than on single readings against fixed thresholds.

Answer: C

Each step has an instrument that confirms it, and the crew watches for a missing confirmation rather than for a fault message. A rising temperature without rising speed is the hung start the sequence is designed to catch.

Answer: D

The compensated leads matter because any dissimilar metal junction in the circuit would add its own voltage. Compensation then converts the difference the thermocouple actually measures into the absolute value the crew reads.

Answer: A

Correct answer: 1, 2, 3, 4, 5

The chain is causal and each step follows from the one before. A leak develops, so oil quantity begins to fall. With less oil in the system the pump eventually draws air and pressure fluctuates and then falls.

Temperature rises next, since the reduced quantity must carry away the same heat. The crew's response comes after those indications, reducing power to lower the heat load and diverting. Bearing damage is the outcome only if the engine keeps running without oil film, which is why the response is placed before it rather than after - the whole point of the drill is to arrive at step four before step five.

Answer: B

The target depends on the day's conditions, so it cannot be a fixed number. The final cross-check exists because a blocked pressure probe would let the ratio indicate correctly while the engine is not actually at that thrust.

Answer: C

The escalation matches the response expected of the crew, from monitoring through timely action to immediate action. The dark cockpit principle means that in normal operation none of the upper three is displayed at all.

Answer: D

Correct answer: Only three

The first three pairs are correct. A tachometer indicates rotor speed as a percentage of a datum; engine pressure ratio is turbine discharge over compressor inlet pressure; and a torquemeter measures shaft torque on a turboprop.

The fourth is wrong. A manifold pressure gauge reads the absolute pressure in the induction manifold, referenced to vacuum, not a difference across the throttle. That is why it indicates ambient pressure with the engine stopped, which a differential instrument would not.

Answer: A

Correct answer: Only three

Green, yellow and red are correctly described: normal operating range, caution range for limited periods, and a limit not to be exceeded.

White is the odd one out. On an airspeed indicator white marks the flap operating range, and on engine instruments it is used for such things as a starting range or a transient marking - never for a prohibition. A prohibited range, where one exists, is marked by a red arc, as on a tachometer with a restricted rpm band. So three of the four are correct.

Answer: B

Correct answer: Only three

The first three describe their sensors correctly. A thermocouple generates a voltage from the temperature difference between its junctions; a resistance thermometer works by the change of electrical resistance with temperature; and a continuous fire loop signals by a change in resistance or capacitance when heated.

The fourth is wrong. A torquemeter measures shaft torque, hydraulically from the axial thrust of a helical gear or electrically from shaft strain. Blade angle is measured separately by a propeller pitch indication, and neither measurement is optical.