On November 7, 2020, about 0830 central standard time, an ERCO Ercoupe 415-C airplane, N331BW, sustained substantial damage when it was involved in an accident near Ardmore, Oklahoma. The commercial pilot sustained serious injuries and the two passengers sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The purpose of the flight was for the pilot to take the two passengers in the two-seat airplane on a local flight to photograph a home. The pilot reported the airplane departed with a full fuel load. The pilot was in the left seat while the two passengers shared the right seat . Both seats were equipped with lap belts. After the completing two passes by the house, the pilot felt a “slight shudder” and he announced to the passengers that he thought they were flying through the airplane’s own propeller wash. Immediately after that, the engine started “vibrating so bad” that the pilot thought the engine was going to separate from the airframe.
The pilot attempted to control the vibration by adjusting the throttle to no avail. He did not apply carburetor heat. The pilot then set the airplane up in a glide configuration at which time the airplane banked to the left. The pilot applied full right aileron control, but it did not stop the left turn. The pilot was attempting to land the airplane in a field when it contacted a tree and came to rest inverted.
The airplane sustained substantial damage to the fuselage, both wings, and the empennage. A postaccident examination of the engine and airframe, including the flight controls, revealed no preimpact mechanical malfunctions or failures with the airframe and engine that would have precluded normal operation.
A review of local area meteorological data showed that at the time of the accident, the airplane was likely operating in conditions conducive to the formation of serious icing conditions (at cruise power) per the Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin CE-09-35 Carburetor Icing Prevention.
A review of weight and balance data showed that the airplane was 48 pounds over the maximum weight at the time of engine start.
According to ERCO Ercoupe Information Letter Number 2, the model 415-C does not employ a flight manual, and none is available. According to FAA Type Certificate Data Sheet A-718 for the airplane, it is limited to two seats, but the data sheet does not address the topic of two passengers sharing a single seat together. The FAA has issued a clarification on the interpretation of the seat belt and seating requirements for general aviation flights and states in part:
This clarification states that the use of a seat belt and/or seat by more than one occupant is permitted only if the seat usage conforms to the limitations contained in the approved portion of the Airplane Flight Manual (AFM). In addition, before multiple occupants use the same seat and/or seat belt, if the pertinent information is available, the pilot in command (PIC) must also check whether: The seat belt is approved and rated for such use; and the structural strength requirements for the seat are not exceeded. This clarification also emphasizes that, because it is safer for each individual person to have his or her own seat and seat belt, whenever possible, each person onboard an aircraft should voluntarily be seated in a separate seat and be restrained by a separate seat belt.