Piper PA 28-180 N4931L accident near Quincy, California

Probable cause

The partial loss of engine power during takeoff due to the separation of the exhaust baffling, which resulted in a partial blockage of airflow to the engine. Contributing to the accident was maintenance personnel’s inadequate inspection of the exhaust system during the airplane’s most recent maintenance.

NTSB analysis

The pilot reported that, shortly after takeoff, the airplane would not climb; therefore, he chose to make a precautionary landing onto a nearby field. During the final approach, the stabilator impacted a fence post, and the pilot subsequently landed the airplane uneventfully.

During a postaccident examination of the exhaust system, the baffles within the muffler assembly were found partially separated and blocking the exhaust ducts, which would have restricted the airflow in the ducts and resulted in a loss of engine power when the airplane reached a higher engine rpm setting during takeoff. No additional mechanical anomalies were observed that would have precluded normal operation.

The airplane manufacturer's service manual states, in part, "a very thorough inspection of the entire exhaust system, including the…muffler and muffler baffles, stacks, and all exhaust connections and welds must be accomplished at each 100-hour inspection. The possibility of exhaust system failure increases with use." The airplane's most recent annual inspection, which should have included the items from the 100-hour inspection, occurred about 3 flight hours before the accident. Maintenance records indicated that maintenance personnel inspected the exterior of the muffler system; however, the records did not indicate that maintenance personnel performed the airplane manufacturer-recommended exhaust system inspection.

Text from the NTSB. Open the NTSB docket for WPR14LA249 for the full record.