On December 17, 1995, a Maule M-4 (registration N12010) was involved in an aviation accident near Hot Springs, SD. Investigators recorded the probable cause as: The pilot's decision to block engine cooling and carburetor air inlets with cardboard, which resulted in reduced engine performance and an inability to climb. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot blocked engine cooling and carburetor air inlets with cardboard to increase cabin heat, resulting in a loss of climb performance and a subsequent forced landing.
What happened
The pilot reported that prior to flight, he attempted to improve the amount of heat reaching the cabin by blocking two specific air inlets located on the engine. To achieve this, he used cardboard to cover the openings. One of these inlets is designed to allow cooling air to enter the engine cowling, while the second inlet supplies necessary air directly to the carburetor.
After takeoff, the pilot noticed that the airplane was unable to climb as expected. Due to the loss of performance, he was forced to execute a landing away from the departure airport.
Probable cause
The pilot's decision to block engine cooling and carburetor air inlets with cardboard, which resulted in reduced engine performance and an inability to climb.
