Piper PA-28-140 accident near Augusta, Kansas, April 1, 2021

The NTSB's narrative final · quoted from the NTSB record

The pilot was performing a practice instrument approach with a safety pilot onboard when the accident occurred. Upon crossing the final approach fix inbound, he reduced engine power to initiate a descent. Shortly afterward, he attempted to increase engine power slightly; however, there was no response. He subsequently applied full throttle without any corresponding increase in engine power. Attempts to restore adequate engine power were not successful and the pilot executed a forced landing to a field during which the airplane sustained substantial damage. A postaccident examination revealed that the throttle cable had become disconnected from the carburetor throttle arm. The attachment hardware was not located. The airplane parts catalog specified that a castellated nut and cotter pin be used to secure the throttle cable rod end bearing to the carburetor. No other anomalies with respect to the engine, carburetor, or throttle cable were observed. The airplane maintenance records indicated that the carburetor was replaced about 23 flight hours before the accident. An annual inspection was completed about 11 flight hours before the accident. Based on the available information, it is likely that the throttle cable was not properly secured to the carburetor throttle arm when the carburetor was replaced; specifically, the cotter pin was not installed. The missing cotter pin was not detected during the annual inspection. The engine power available at the time the cable became disconnected was not sufficient to maintain altitude, resulting in a descent and forced landing.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.