Avionics and Engine Diagnostics: The Overlap in Aircraft Engine Troubleshooting
In the digital era of aviation, avionics and engines are no longer separate concerns. Today’s aircraft engines rely heavily on electronic systems—ranging from sensors and data buses to software-controlled FADECs (Full Authority Digital Engine Controls). That means effective aircraft engine troubleshooting is just as much about interpreting electronic signals as it is about diagnosing mechanical faults.
In this guide, we’ll explore how avionics affect engine performance, common failure points, and diagnostic strategies that combine mechanical insight with electronic precision. Whether you're a technician, operator, or aviation engineer, this knowledge is vital for reducing downtime and maintaining flight readiness.
The Role of Avionics in Engine Health
At the heart of every modern engine is a complex control and monitoring network:
FADEC systems oversee fuel flow, thrust settings, and engine parameters.
Sensors measure temperatures, pressures, RPM, and vibrations.
Wiring harnesses transmit data between the engine bay, cockpit, and central maintenance computer (CMC).
EICAS or ECAM displays relay engine status and fault alerts to the flight crew.
A fault in any part of this digital chain can result in abnormal readings, false warnings, or even performance limitations.
Common Avionics-Related Engine Issues
Understanding the overlap between avionics and engine performance is crucial. Here are the most common issues:
1. Sensor Failures
Faulty temperature or pressure sensors can cause false EICAS alerts or prompt the FADEC to derate engine performance unnecessarily. In worst-case scenarios, it may trigger an engine shutdown.
2. Data Bus Communication Loss
Systems like ARINC 429 or CAN bus carry critical data between the FADEC, cockpit instruments, and CMC. Intermittent signal loss can lead to phantom alerts or degraded engine control.
3. Power Supply Instability
Voltage drops or EMI (electromagnetic interference) in the engine bay can impact the reliability of both sensors and FADEC logic boards.
4. Software Mismatches
Using outdated or incompatible firmware in engine control systems can cause erratic behavior, false fault codes, or failure to meet updated performance benchmarks.
5. Wiring Harness Fatigue
Repeated thermal cycling and vibration can lead to insulation breakdown or chafing, especially where wires pass through high-heat zones or bulkheads.
Step-by-Step Aircraft Engine Troubleshooting Process
Modern troubleshooting goes far beyond checking fuel lines and spark plugs. Here's a streamlined process used by professional aviation technicians:
Step 1: Review Flight and Fault Logs
Start with pilot reports and automated data downloads. Use onboard BITE (Built-In Test Equipment) results or ACARS data to identify any abnormal parameters.
Step 2: Inspect Sensor Outputs
Cross-reference suspect sensor data with adjacent systems. If EGT readings are high but vibration and RPM are stable, a sensor fault may be more likely than a real over-temp.
Step 3: Check Power and Grounding
Use multimeters and oscilloscopes to validate voltage consistency. Look for signs of poor grounding, such as erratic sensor behavior or repeated system resets.
Step 4: Verify Software Configuration
Ensure that the FADEC and CMC are running compatible firmware versions. Misalignments can cause improper alerts or inhibit valid troubleshooting data.
Step 5: Conduct Ground Runs
If necessary, perform an engine test run while monitoring all digital and analog outputs. Use diagnostic software to capture real-time data for analysis.
For a deeper dive, the FAA Advisory Circular on Digital Engine Control Systems outlines certification, monitoring, and diagnostic standards in commercial and general aviation engines.
Preventive Strategies for Engine-Avionics Reliability
1. Routine Sensor Calibration and Health Checks
Calibrate sensors at regular intervals. Replace or bench-test those that show signal drift, even if no alert has been triggered.
2. Environmental Shielding
Install EMI filters, proper routing brackets, and heat shields to protect signal integrity—especially near turbine engines or high-frequency antennae.
3. Wiring Harness Maintenance
Inspect and re-secure wire bundles using borescope and megohmmeter testing to check for insulation breakdown or water intrusion.
4. Software Version Management
Track software updates across all integrated systems. Align FADEC, cockpit displays, and maintenance computers to avoid incompatibilities.
The EASA Engine Certification Resources also provide technical bulletins and airworthiness guidance that align with industry best practices.
Case Study: ERJ-145 Thrust Control Dropouts
An Embraer ERJ-145 fleet experienced multiple instances of automatic thrust rollback during climb. Engineers discovered that corrosion in a pressure sensor’s connector was feeding erratic data to the FADEC. Although the engines were mechanically sound, the digital systems misinterpreted the data as a threat and limited thrust to idle.
This example underscores the importance of evaluating both physical components and data quality when addressing aircraft engine troubleshooting.
Emerging Trends in Engine Diagnostics
AI-Powered Health Monitoring: Machine learning tools are now used to detect performance anomalies before traditional sensors register them.
Cloud-Based Predictive Maintenance: Systems like Pratt & Whitney’s eFAST and GE’s Health Monitoring stream engine performance data to ground crews in real time.
Cybersecurity Integration: As engine controls become networked, new protocols are being developed to secure FADEC and avionics software from unauthorized access or disruption.
Conclusion
In modern aviation, engine troubleshooting is no longer limited to torque wrenches and thermocouples. It demands a multidisciplinary approach—one that balances mechanical knowledge with a command of avionics and software systems.
Whether you're maintaining a turboprop or a wide-body jet, successful aircraft engine troubleshooting means mastering the intersection of electronics, power systems, sensors, and diagnostics. With the right tools and training, technicians can keep aircraft engines—and the systems that support them—operating with maximum reliability.
