Air Tractor AT504 N8516V accident near Big Cypress, Florida

Probable cause

The pilot’s decision to depart with cargo outside of the designated baggage compartment, which resulted in the cargo interfering with the rudder control system.

NTSB analysis

During the first leg of a ferry flight the pilot reported that, while descending through 9,000 ft above ground level (agl), the airplane yawed left violently. Even with application of pressure to the right rudder pedal, the airplane continued in a left descending turn until impacting swampy terrain. The airplane sustained substantial damage to the left wing and engine mounts.

Postaccident examination of the airplane revealed that a large amount of baggage and cargo had been zip-tied to the tubular metal fuselage structure aft of the baggage compartment and under the cockpit area. Multiple zip ties were found cut and others were found loose. The loose and cut zip ties were found in the vicinity and around a large piece of spray equipment that had been wrapped in plastic, as well as a box both, both of which could be moved by hand when pressure was applied. These items were in the vicinity of both the right rudder direct drive cable and the right rudder/aileron interconnect cable. The examination otherwise found no evidence of any preaccident mechanical malfunctions or failures of the airplane that would have precluded normal operation. Based on this information it is likely that the cargo shifted during the flight and interfered with the rudder control system, resulting in the rudder hard over.

The weight and balance filled out by the pilot prior to the flight showed that he had accounted for cargo and baggage outside the airplane’s designated baggage compartment. While this showed that the airplane was likely being operated within its center of gravity envelope it, the pilot’s decision to operate the flight with cargo outside the designated area did not account for the potential that the cargo would shift in such a way that it could interfere with the flight controls.

Text from the NTSB. Open the NTSB docket for ERA25LA079 for the full record.