Pilot Debrief

AERO COMMANDER S2R near Vinton, IA — 2018-07-17

Final reportCEN18LA278
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Date
2018-07-17
Location
Vinton, IA, USA
Airport
KVTI
Aircraft
AERO COMMANDER S2R
Registration
N5553X
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

Loss of throttle control input due to a failure in the throttle control system. Contributing to the accident was the inadequate inspection and reinstallation of worn parts by maintenance personnel.

NTSB narrative

The pilot stated that on final approach, he slowed the airplane for landing. When the airplane crossed the end of the runway, he reduced the throttle back, but the airplane would not slow, so he executed a go-around. During the go-around, the engine lost partial power and would not respond to the pilot’s throttle inputs. The pilot then executed a forced landing in a cornfield, and the airplane sustained substantial damage to the fuselage and empennage. Examination of the throttle control system revealed that the interlocking teeth mechanisms between the carburetor lever stop assembly and the throttle control lever were worn and lost integrity to interconnect. The teeth on the lever stop assembly were severely worn. Thus, it is likely that during the accident flight, when the pilot actuated the throttle control lever, the throttle control system failed when the worn-down teeth on the lever stop would not engage the teeth on the mating throttle control lever. This caused a loss of the throttle lever input, which allowed the engine to enter a low rpm condition. The material examination also noted a mismatch in hardness of the associated parts; although the hardness values were typical for the respective part compositions and microstructures, the mismatch in hardness lent itself to higher wear rates. A review of the airplane’s maintenance records revealed that the carburetor had been removed for overhaul and reinstalled 135 hours before the accident. It is likely that maintenance personnel reinstalled the worn parts without thoroughly inspecting them.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Throttle control failure during approach could have prompted an earlier go-around decision.

NTSB coding

Evidence available

  • Photos
  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

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