Cessna 182N N703Z

Summary

On 6 July 2023 at about 16:17 local time, a Cessna 182N registered N703Z was involved in an accident near St Maries, Idaho, United States. One person was on board and one died. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

6 July 2023 at 16:17

Classification

Accident

Location

St Maries, Idaho, United States

Nearest airport

St Maries Muni (S72)

Coordinates

47.3223, -116.5615

Aircraft

Cessna 182N

Registration

N703Z

Category

Airplane

Year built

1971

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR23FA256

1 person died.

The total loss of engine power due to the failure of the No. 3 exhaust valve for reasons that could not be determined. Contributing to the accident was the pilot’s failure to maintain control of the airplane after the loss of engine power.

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

Read the full NTSB narrative

Shortly after takeoff, the airplane lost engine power and the pilot transmitted “failure” over the Common Traffic Advisory Frequency (CTAF). Witnesses reported hearing the engine popping and sputtering and seeing smoke coming from the airplane. They reported the airplane turned and descended to impact with the terrain. ADS-B data indicated the airplane reached a maximum altitude of 240 ft before it descended to impact a hay field about 0.5 nautical miles from the departure end of the runway. Postaccident examination revealed that the No. 3 engine cylinder exhaust valve head was separated from its stem. The exhaust valve fractured at its neck in cyclic brittle overstress initiating at the stem’s core and propagating to the edges, with the final separation at the shear lip. The valve stem and guide exhibited excessive wear and thermal discoloration. It could not be determined if this was due to operational wear or if the valve guide or stem was built to specification at the time of assembly. Although the engine had only 935 hours total time (565 hours short of the recommended overhaul period) it was 19 years since the last overhaul. Teledyne Continental Motors Service Information Letter SIL98-9C states the time between overhaul for the IO-470 series engines is 1,500 hours or every 12 years, whichever occurs first. Following manufacturer overhaul periods is not required for Part 91 operations. However, since the last overhaul in 2004, the Nos. 1 and 2 cylinders were repaired, including replacement of the No. 2 valve guide.

Quoted verbatim from the NTSB record.