Socata TB200 N207GT accident near Annapolis, Maryland

Probable cause

A loss of engine power for undetermined reasons after the disconnection of the propeller governor control due to inadequate securenment during maintenance.

NTSB analysis

The pilot stated that, about 45 minutes after departure, he felt a subtle vibration in the engine. A few minutes later, the propeller rpm increased uncommanded to 2,700 rpm and remained "pegged at the redline." The pilot was unable to control the rpm and the vibration increased, followed by smoke in the cabin and a loss of engine power; the pilot subsequently performed a forced landing, impacted a pole and guardrail, and the left wing and horizontal stabilator separated.

Postaccident examination of the engine revealed that the propeller governor control arm had disconnected from the propeller governor. It is likely that during maintenance conducted 5 months before the accident, the linkage was not properly secured, and the bolt eventually backed out of the propeller control arm, which resulted in the separation; however this would not have directly resulted in the loss of engine power. The examination of the airframe and engine was otherwise unable to identify a definitive cause for the loss of engine power.

Text from the NTSB. Open the NTSB docket for ERA18LA021 for the full record.