The PremierMRO team in Dayton completed an impressive list of repairs on a King Air C90B, boosting performance and reliability. The aircraft entered PremierMRO’s Dayton facility with on-going engine issues, autopilot malfunction, and intermittent right-hand engine start problems. Thanks to the expertise of the technicians, performance and reliability concerns that were documented in the aircraft’s logbook for over 15 years have been fully rectified.
ITT Split Diagnostics
Initial observations of the engines showed a 30° difference between the right and left engines at altitude. The ITT readings showed one engine consistently running hotter despite matched settings. The PremierMRO team checked T5 temperature sensors and wiring continuity to ultimately discover the wiring issue. After repairing the wiring, the ITT split was reduced to 15°, well within acceptable limits.
The wiring repair was integral to improving the performance and reliability of the King Air C90B making for a very satisfied customer.
Avionics and Autopilot Fixes
In addition to the wiring harness repair, the team resolved avionics and autopilot issues reported by the owner, who noted that the Garmin autopilot was not engaging properly. PremierMRO technicians tested autopilot engagement and reviewed communication between the Garmin and Collins components, ultimately tracing the issue to the Collins #2 directional gyro. The gyro was functioning but not providing data to the rest of the system or the autopilot due to an internal fault, which prevented full autopilot functionality.
Without a replacement on hand, the team simulated the signals normally sent by the gyro to confirm that the rest of the system was operating as intended. With customer approval, a new Collins directional gyro was installed, restoring proper heading indications and full autopilot functionality.
Right-Hand Engine Start Issue
The King Air C90B client was also experiencing intermittent right-hand engine start issues, especially during cold starts. The owner reported that the engine would fail to light unless connected to a power cart. The team went to work troubleshooting the issue by swapping starter relays between engines and connecting with Textron for additional diagnostic steps and system checks. Ultimately, the team rectified the issue so both engines start every time.
PremierMRO’s Excellence in Service
All of the issues on the King Air C90B posed significant diagnostic challenges, from electrical to avionics, that our team was able to rectify. Their commitment to providing top-tier service is reflected in their ability to fix all of the issues on the aircraft and finally clear the logbooks of long-standing issues. Going the extra mile and finding ways to identify and fix performance and reliability issues is part of what has built the PremierMRO technicians’ reputation for service excellence that sets us apart and makes us a top choice for clients in throughout the MidWest.
Compliance & Safety Notice: This case study is informational only and not approved maintenance data. All work must be performed by certificated personnel using current OEM/ICA documentation or other FAA-acceptable methods (14 CFR §43.13).