Incident Overview
While approximately 20 miles from the destination airport, the pilot reported smelling smoke and observing erratic engine instrument readings. The landing gear was extended, and three green lights indicated that the gear was down and locked. Shortly thereafter, the gear warning light and horn activated. During the landing, the gear remained extended, and the pilot taxied to the ramp with the warning systems still active.
Post-Flight Inspection
A subsequent inspection revealed that the left muffler was broken at its forward end, at the attachment point to the exhaust riser. Three wire bundles leading to the firewall were found melted. The muffler's flame tube had been replaced and the muffler reinstalled approximately 37 operational hours prior to the incident. The flame tube was observed to be rubbing vertically across the area where the muffler had failed.
Sequence of Events
The pilot initially noted the smoke smell and erratic instruments while still some distance from the destination. The decision to extend the gear was made, and the gear appeared to be properly down and locked based on the three green indicator lights. However, the subsequent activation of the warning light and horn indicated a discrepancy in the gear system. Despite the warnings, the gear remained extended throughout the landing, and the pilot continued to the ramp with the warnings still active. The inspection findings point to a mechanical failure in the exhaust system, with the broken muffler and melted wiring suggesting a heat-related issue.