WWAOG Technical Academy · Guided workshop

King Air Engine Indications & Sensor Fault Isolation

Explore the named components, make a prediction, then connect the supplied result to the system. This workshop adds coached practice alongside the course handbook and assessed lab.

TM-074 · Visual systems workshop

See what an indication test actually includes

An engine indication can respond to a test signal while its disconnected sensor remains untested. Follow the actual sensor, a substituted input, the two data sources and the selected screen. Predict each fictional result before revealing it, then explain what the observation establishes.

01 / Explore the relationships6 selectable components

Functional indication relationships. DCU and EDC are alternative data sources, not units connected in series. Real-sensor and substituted-signal arrows represent different test conditions; the diagram is not a connector or wiring instruction.

Green outlines identify components named in the selected exercise record; they do not indicate a healthy component.

Named connections and what each arrow means

Actual engine sensor → Normal DCU sourceInformation / signal: Actual parameter input: installed normal route
Actual engine sensor → Secondary EDC sourceInformation / signal: Actual parameter input: installed secondary route
Qualified substituted signal → Normal DCU sourceInformation / signal: Substituted aircraft-side input in named check
Qualified substituted signal → Secondary EDC sourceInformation / signal: Substituted aircraft-side input in named check
Normal DCU source → Engine indication and comparatorInformation / signal: Normal engine-data source
Secondary EDC source → Engine indication and comparatorInformation / signal: Secondary engine-data source
DISPLAY screen selection → Engine indication and comparatorTask sequence: Presentation selection

Component purpose

Actual engine sensor

Converts the named physical engine quantity into an electrical input.

How it works with the rest

In the supplied exercises, the actual item is either the MT4 propeller tachometer generator or the MT5 fuel-flow transmitter. The generator responds to its mechanical drive; the transmitter responds to actual fuel flow. A source connected on the aircraft side of a disconnected sensor connector bypasses that sensor. Its successful indication cannot establish the excluded drive, transmitter or physical quantity.

What the evidence must show

Identify the parameter, sensor and connection point. Record whether the real sensor was connected during the observation.

Selected: Actual engine sensor

02 / Predict · reveal · explain

Follow the change through the system.

0 / 3 exercises reviewed

Exercise brief · supplied training conditions

Fictional left-engine record under the complete 77-40-09 propeller-RPM indication-check setup: the MT4 generator is disconnected at P21. The named qualified function-generator signal is supplied to the aircraft-side indication path. Predict what a satisfactory displayed response can establish; the real generator is excluded.

Before the recorded change

Actual MT4 generator: disconnected. Named P21 test signal and complete applicable setup: supplied. Expected indication in this task: green 1600 ± 30 RPM on the MFD. Actual result is hidden.

Next observation

Choose your prediction before revealing the supplied result.

Reference: Textron 130-590031-11, B300/B300C Maintenance Manual, 77-40-09 p. 601, April 15, 2023; supplied Chapter 77 PDF p. 67. Indication-only scope, qualified stimulus and 1600 ± 30 RPM comparison.

Predict the resultWith the propeller tachometer generator disconnected, what can a satisfactory RPM indication from the function-generator input at P21 establish?

The included downstream indication responds; the disconnected generator still needs its own evidence.The actual generator responds correctly; the aircraft-side input has reproduced its complete mechanical drive.The generator drive is satisfactory; the substitute signal has measured the engine’s actual propeller speed.Both physical generator and indication pass; the matching value covers both sides of the disconnected connector.

Course applicability and study references

The identified B300/B300C Pro Line 21 integrated engine-indication installation in Textron 130-590031-11, 77-40-00, 77-40-07 and 77-40-09: FL-381, FL-383 and After; FM-12 and After. This supplement uses fictional records prepared under the named task conditions. It does not extend these electrical checks to every standalone indication or replace current applicable aircraft instructions.

Normal and secondary engine-data sources
Textron 130-590031-11, 77-40-00 p. 1, April 1, 2018; supplied Chapter 77 PDF p. 53. Defines DCU normal and EDC secondary roles and engine-display functions.
Fuel-flow indication and presentation check
77-40-07 pp. 601–602, April 15, 2023; supplied PDF pp. 63–64. Defines the indication-only P6 check, named supply states, comparator observation, DISPLAY selection and restoration.
Propeller-RPM indication check
77-40-09 p. 601, April 15, 2023; supplied PDF p. 67. Defines the qualified P21 substitute signal and 1600 ± 30 RPM indication. The real generator is excluded from this electrical check.

Original learning diagrams and supplied training records explain the stated relationships. Current aircraft-effective instructions and authorization govern actual maintenance.