Schweizer G-164B N7503L

Summary

On 9 July 2011 at about 21:30 local time, a Schweizer G-164B registered N7503L, operated by Onstott Dusters Inc, was involved in an accident near Yuba City, California, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

9 July 2011 at 21:30

Classification

Accident

Location

Yuba City, California, United States

Coordinates

39.0683, -121.7353

Aircraft

Schweizer G-164B

Registration

N7503L

Category

Airplane

Engines

1

Operator

Onstott Dusters Inc

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Yuba City → Yuba City

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR11LA320

Nobody was injured.

High-cycle fatigue on the 1st-stage compressor blade retaining ring, which resulted in the ring’s fracture and a subsequent loss of engine power.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot reported that, during the initial climb, he heard a "loud pop" and observed fire coming from both exhaust stacks before the engine lost power. He subsequently made an off-airport landing to an adjacent road. During the landing, the airplane slid into a ditch, the landing gear sheared off, and the airplane nosed over. A postaccident engine examination revealed that the blade retaining ring of the 1st-stage compressor blades had fractured into several pieces; about 30 percent of the ring was not recovered. A metallurgical examination of the recovered sections of the retaining ring revealed that all but two of the fractures were due to ductile overload. An examination of the nonoverload fractures revealed fatigue originating from the rivet hole areas, which was indicative of high-cycle fatigue. The power section had been overhauled 747 hours before the accident. According to the overhaul manual current at the time of the overhaul, the blade retaining ring was an on-condition inspection item and not required to be replaced at overhaul. The fatigue fracture of the 1st-stage compressor blade retaining ring likely affected the engine's ability to produce power.

Quoted verbatim from the NTSB record.