Casualties unknown

Engine Failure After Departure Leads to Shoreline Landing in Float-Equipped Airplane (N7797B)

Skwentna, AK, US

On August 14, 1996, a Piper PA-18 (registration N7797B) was involved in an aviation accident near Skwentna, AK. Investigators recorded the probable cause as: An engine failure due to an eroded engine piston. Factors in the accident were unsuitable terrain for a forced landing and improperly timed magnetos. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A private pilot and passenger experienced an engine failure shortly after departing a remote lake in a float-equipped airplane, resulting in a forced landing on the shoreline. Postaccident inspection revealed a locked piston ring and degraded cylinder.

Departure and Engine Failure

A certificated private pilot and sole passenger departed a remote lake in a float-equipped airplane. Approximately three minutes after takeoff, the engine began to run rough and subsequently ceased operating. The pilot initiated a turn back toward the lake but was unable to reach it by gliding, instead landing the airplane on the shoreline.

Postaccident Inspection

Examination of the engine after the accident disclosed a lack of compression in the number 4 cylinder. The top piston compression ring was found frozen in its groove. The outer and upper edges of the piston crown were eroded and scored. Tiny metallic particles originating from the piston material were observed adhering to the spark plugs. Additionally, one magneto was timed at 4 degrees before the recommended setting of 25 degrees.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001208X06402. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.