VANS RV-7A

Full Narrative

On December 22, 2024, about 1639 mountain standard time, an experimental amateur-built Vans RV-7A airplane, N1FB, was substantially damaged when it was involved in an accident near Gila Bend, Arizona. The pilot sustained minor injuries, and the passenger was not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight.
According to the pilot, after departing Phoenix Goodyear Airport (GYR), Phoenix, Arizona, he climbed the airplane to 2,000 ft above mean sea level (msl). After clearing the Class B airspace shelf, he proceeded to climb to the planned cruise altitude of 4,500 ft msl. About 4,000 ft msl, he adjusted the fuel mixture and engaged the autopilot. About four minutes later, he felt abnormal vibrations from the engine. He began to troubleshoot, but the engine continued to run rough and lose power. The pilot stated that manipulation of the mixture control had no corresponding effect, and that he noticed a lack of tension on the mixture control cable. He moved the throttle control from full throttle to about halfway toward idle, and the engine roughness slightly subsided, but the engine rpm decreased and the engine lost total power.
The pilot turned the airplane toward the nearest airport, but realized the airplane would not reach the runway, and he performed a forced landing to a field with tall desert vegetation. During the landing roll, the airplane’s landing gear contacted a ditch and the airplane nosed over, resulting in substantial damage to the left wing.
Postaccident examination of the fuel system revealed the bolt that connected the mixture control cable to the mixture control arm had backed out. The missing bolt was recovered from the lower cowling in a pile of brush consistent with vegetation observed at the accident site. The bolt showed no deformation signatures, and the adjoining washers, castellated nut, and cotter pin were not recovered. The bolt that secured the rod end bearing to the mixture bellcrank and its associated hardware was present and unremarkable. The mixture control arm was found in the idle-cutoff position. The throttle linkage attachment bolts, washers, castellated nuts, and cotter pins were present and unremarkable. Review of the airplane’s engine logbook indicated that the engine controls were checked and lubricated during a condition inspection dated February 7, 2024. An entry dated December 2, 2024, stated that the engine crankshaft seal was cleaned and reinstalled due to oil leaks, a magneto was replaced and magneto timing checked, engine oil and oil filter were changed, and new crankshaft propeller flange bushings were installed. The entry stated that the engine was inspected in accordance with the scope and detail of Part 43 Appendix D. Whether any of this work required disconnecting the mixture control cable/arm was not determined.
14 CFR Part 43 Appendix D details items to be included in annual and 100-hour inspections. The components listed for inspection of the engine includes, “Engine controls – for defects, improper travel, and improper safetying.”