Cessna 172H N2550L

Summary

On 19 May 2023 at about 01:17 local time, a Cessna 172H registered N2550L was involved in an accident near Seattle, Washington, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

19 May 2023 at 01:17

Classification

Accident

Location

Seattle, Washington, United States

Coordinates

47.6131, -122.3553

Aircraft

Cessna 172H

Registration

N2550L

Category

Airplane

Year built

1967

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Port Townsend → Seattle

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR23LA196

1 person had minor injuries.

A stuck exhaust valve that resulted in a partial loss of engine power and a forced water ditching.

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

Read the full NTSB narrative

The pilot reported that, as the airplane descended to 1,000 ft mean sea level (msl) crossing over a bay, the engine sustained a partial loss of power. The pilot declared an emergency and performed a forced water ditching. Examination of the engine revealed a stuck exhaust valve on the No. 4 cylinder. The No. 4 cylinder was removed for further examination. The exhaust valve guide exhibited evidence of oil coking along with an area of polishing on one side of the guide. A slight amount of discoloration consistent with corrosion was observed adjacent to the polished area. The exhaust valve stem was intact with some coking near the valve fillet and the intake valve exhibited moderate coking. It is likely that the coking resulted in the valve getting stuck. The Nos. 2 and 4 cylinder cooling fins exhibited thermal discoloration. A visual inspection of the internal area of the crankcase showed the crankshaft and camshaft did not reveal any anomalies or mechanical damage. The No. 4 cylinder had been serviced and reinstalled with a new cylinder kit 143 flight hours before the accident and the most recent annual inspection was about 11 months before the accident.

Quoted verbatim from the NTSB record.