Pilot Debrief

BELLANCA 8GCBC near Frankford, DE — 2024-07-04

Final reportERA24LA299
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Date
2024-07-04
Location
Frankford, DE, USA
Aircraft
BELLANCA 8GCBC
Registration
N749SK
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Climb

Probable cause

A partial loss of engine power resulting from cylinder detonation and a cracked spark plug, which resulted in a forced landing and impact with terrain.

NTSB narrative

The pilot was flying at 300 ft mean sea level (msl) while towing a banner when he noticed the engine oil temperature began to increase. The pilot informed the operator and climbed to 1,200 ft msl; however, the airplane would not maintain altitude and was slowly descending. The engine rpm began to decrease and the engine increasingly began to run rough. The pilot dropped the banner as the airplane descended through 700 ft msl, and he initiated a forced landing in a field that was bordered by trees. Unable to reach the field, the airplane impacted the top of trees. The airplane then descended to the ground, resulting in substantial airframe and wing damage. Postaccident examination of the engine revealed damage to the No. 3 cylinder that was consistent with detonation in the form of erosion on the edge of the intake valve and valve seat insert, and a cracked lower spark plug that was likely the cause of the detonation. A review of the most recent annual inspection maintenance logs revealed that the No. 3 cylinder assembly was replaced with a new cylinder 45 days before the accident.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have opted to land earlier when engine issues began.

NTSB coding

Evidence available

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

Docket documents6

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