PIPER PA-28-140 near Augusta, KS — 2021-04-01

Probable cause

Inadequate maintenance at the time the carburetor was replaced, which resulted in the improperly installed throttle cable and a partial loss of engine power. Contributing to the accident was an inadequate annual inspection that failed to detect the improper throttle cable installation.

NTSB narrative

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.

Analysis

Primary failure mode

Mechanical failure

First missed decision gate

Pilot could have aborted the approach after initial power loss.

NTSB coding

• Loss of engine power (partial) · Approach-IFR final approach
• Maintenance

Evidence available

• Photos
• 9 docket documents

Docket documents9

• PILOT/OPERATOR AIRCRAFT ACCIDENT REPORT, NTSB FORM 6120.1form
• PILOT STATEMENTinterview
• SAFETY PILOT STATEMENTinterview
• AIRPLANE EXAMINATION SUMMARYother
• AIRPLANE PARTS CATALOG (EXCERPT) -- ENGINE CONTROLS INSTALLATIONother
• FAA TERMINAL PROCEDURE -- VOR/DME Aother
• MAINTENANCE RECORDS -- AIRFRAMEother
• MAINTENANCE RECORDS -- ENGINEother
• ACCIDENT PHOTOSphotos

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