PITTS S1S

Full Narrative

On December 31, 2025, at 1603 central standard time, a Pitts S1S airplane, N401MS, was substantially damaged when it was involved in an accident near Carbondale, Illinois. The pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that he had completed three touch-and-go landings on runway 36R. He then completed a low approach over runway 18L and began a climb near the departure end of the runway. Upon reaching 400 ft agl, the engine lost power. The pilot was able to momentarily restore partial power by manually actuating the emergency fuel pump; however, the engine lost power again. Unable to maintain altitude, the pilot completed a forced landing on an airport perimeter road, then exited the road to the right and struck a power pole. The left wing separated from the airplane during the impact.

Postaccident examination revealed the engine crankshaft was fractured which was consistent with the ground impact. Additionally, the left side of the engine no. 2 cylinder exhibited impact damage. No anomalies were noted with the engine; however, no indication of fuel was present at the fuel manifold when disassembled. Disassembly of the fuel manifold revealed the four cover screws were not safety wired and found loose, and the manifold diaphragm contained red silicone on both sides. Throttle control continuity and full motion of travel was confirmed from the cockpit to the engine fuel servo.

A review of the maintenance logbooks indicated that several fuel lines were replaced aft of the firewall, and a fuel flow transducer was installed forward of the firewall along with an engine monitor, at 122.4 hours total airframe time, and 3.6 hours before the accident. Examination found the mixture control cable was not secured at the fuel injection servo. The mixture cable was secured by a cushion clamp on the engine mount about 10 inches from the servo, and the cable sheath was not secured near the servo. Safety wire used to secure the cable was found severed, and the cable outer sheath exhibited flexing when the cockpit mixture control was actuated. With the cockpit mixture control in the full rich position, the engine fuel injector mixture lever position corresponded to about mid-range. A full rich mixture setting at the engine fuel injector servo could not be achieved.