On April 25, 2025, an Amazon Prime Air Boeing 767-319, registration N347AZ, departed Ontario International Airport (ONT) in California, bound for Lihue Airport (LIH) in Hawaii. During the descent into Lihue, the flight crew experienced repeated autopilot disconnections. After attempting the autopilot disconnect checklist without success, the crew began hand-flying the aircraft at approximately 10,000 feet. The crew reported that significant down pressure on the yoke was necessary to maintain a descent.
Upon inspection, the crew identified that the horizontal stabilizer was inoperative, indicated at 3.4 units on the stabilizer position indicator. Despite attempts to use the alternate electric trim switches, the stabilizer remained stuck. The crew subsequently leveled the aircraft at 3,000 feet and selected flaps 5 to reduce the control column force required for pitch control. After performing both the stabilizer trim checklist and the unscheduled stabilizer trim checklist from the quick reference handbook (QRH) with no improvement, the crew declared an emergency and diverted to Daniel K. Inouye International Airport (HNL).
The aircraft landed safely at HNL with flaps 25 selected. There were no injuries and no fatalities during the event.
The investigation
The NTSB upgraded the investigation from a class 5 to a class 3 investigation in September 2025. The investigation revealed that the horizontal stabilizer trim actuator (HSTA) had been replaced with an overhauled unit during scheduled maintenance approximately one month prior to the incident. At the time of the flight, the overhauled HSTA had been in service for 11 cycles and 31 flight hours. Following the landing, the HSTA was removed and sent to the component manufacturer for examination. The investigation into the flight data is ongoing.