Pilot Debrief

GRUMMAN G-164A near Emmett, KS — 2015-07-31

Final reportCEN15LA330
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Date
2015-07-31
Location
Emmett, KS, USA
Aircraft
GRUMMAN G-164A
Registration
N963X
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The engine failure due to several loose, damaged cylinder stud nuts and hold-down bolts. Contributing to the accident was maintenance personnel’s failure to detect that the cylinder nuts and hold-down bolts were not properly secured during the engine’s most recent inspection.

NTSB narrative

The commercial pilot was conducting an agricultural application flight. The pilot reported that, while making a spray run, he heard a loud "bang" and saw a puff of smoke emanate from the upper right side of the engine, followed by the propeller seizing. He made a forced landing in a field, and the airplane collided with some bushes and then nosed over. Examination of the engine revealed several loose cylinder stud nuts and hold-down bolts that appeared to have been pushed up on the cylinder skirt. Several of the studs, particularly the No. 4 cylinder stud, were stretched and looked to be nearly pushed out of the engine crankcase. One cylinder was almost separated from the crankcase. Examination of the airplane's maintenance logbooks revealed that the engine had received a major overhaul more than 8 years before the accident. The records indicated that, since that time, inspections of the cylinder heads and the cylinder hold-down studs had been conducted in compliance with two Federal Aviation Administration airworthiness directives. The engine was last inspected about 3 months before the accident. During this inspection, maintenance personnel checked the cylinder bases and heads for cracks and loose studs; however, they did not detect that the cylinder nuts and hold-down bolts were not properly secured.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have conducted a precautionary landing before engine failure.

NTSB coding

Evidence available

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

Docket documents7

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