Pilot Debrief

ENSTROM F 28F near Tomah, WI — 2014-08-07

Final reportCEN14LA412
Sign in to save
Date
2014-08-07
Location
Tomah, WI, USA
Aircraft
ENSTROM F 28F
Registration
N213BL
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Climb

Probable cause

A loss of engine power due to the malfunction of the No. 4 cylinder intake valve.

NTSB narrative

The pilot felt a vibration in the cyclic control and he stated that the engine was running irregularly as he neared the intended application field on the agricultural application flight. He immediately elected to execute a precautionary landing to a cornfield; the corn crop was about 10 feet tall at the time. During the landing, the landing skids collapsed, and the tailboom was severed by a main rotor blade. A postaccident examination of the engine revealed that the No. 4 cylinder did not exhibit compression during crankshaft rotation. Further examination of the No. 4 cylinder revealed that the intake valve did not seat properly; a gap of about 0.015 inch existed when the valve should have been fully seated. Linear scoring was observed on the valve stem, and debris consistent with valve guide material was also recovered upon removal of the valve. No other anomalies with respect to the engine were observed. The engine had accumulated about 831 hours since overhaul. The helicopter maintenance records did not contain a record of any unresolved maintenance issues.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have returned to the loading site instead of attempting a precautionary landing.

NTSB coding

Evidence available

  • 11 docket documents
View NTSB final reportView NTSB docket

Docket documents11

Related mishaps