On June 17, 1999, a Ryan NAVION B (registration N870DR) was involved in an aviation accident near Klamath Falls, OR. Investigators recorded the probable cause as: The pilot's failure to reinstall the engine oil filler cap during preflight, resulting in engine oil loss and the necessity for an immediate landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot added oil during preflight but forgot to replace the filler cap, causing oil on the cowling and windscreen. After an aborted landing attempt, the aircraft touched down hard in dirt north of the runway, punching the right main gear through the wing.
Incident
During preflight, a pilot added one quart of oil to the engine. The oil filler cap was not replaced before takeoff.
Immediately after departure from runway 14, the pilot observed oil on the top of the engine cowling and on the windscreen. The pilot requested an immediate return and was cleared to land on any runway.
Landing Attempt
The pilot executed a 60-degree left turn toward runway 25. The engine was running roughly during the approach. The pilot stated that due to altitude, he was unable to reach the runway. The aircraft touched down at approximately a 45-degree angle just north of the runway in a dirt area. The landing was hard enough that the right main landing gear punched through the top of the right wing.
Damage
The aircraft sustained damage to the right wing where the landing gear penetrated the upper surface.