N2876QCessna 172L · 1971

On December 3, 2019, about 2130 central standard time, a Cessna 172L N2876Q, was substantially damaged when it was involved in an accident near Potts Camp, Mississippi. The private pilot sustained serious injuries. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations as a Part 91 personal flight.

The pilot reported that he conducted an instructional flight with a flight instructor earlier during the day and flew 1.5 hours from Olive Branch Airport (OLV) Olive Branch, Mississippi, to Tupelo Regional Airport (TUP) Tupelo, Mississippi. He then returned to OLV, where they landed about 1400 and “topped off” the fuel tanks with 12.8 gallons of 100 low-lead aviation fuel, which brought the total to about 40 gallons. The previous flight was unremarkable with no engine indications or anomalies noted.

Several hours later, the pilot conducted a night solo flight about 1900. After departure, he flew to McKellar-Sipes Regional Airport (MKL), Jackson, Tennessee, and conducted some sightseeing; then he proceeded to TUP, where he performed a touch-and-go landing before returning to OLV at a cruise altitude of 3,000 ft mean sea level. There were no indications or anomalies noticed during the flight until the engine experienced a total loss of power about 20 minutes after departing TUP and about 2 hours since departing from OLV.

He declared an emergency with Memphis air traffic control. The pilot successfully restarted the engine by establishing best glide speed and performing the emergency checklist, which included activating carburetor heat; the responding controller provided heading and distance to Holly Springs-Marshall County Airport (M41) Holly Springs, Mississippi, which was at 12 o’clock and 17 miles. The pilot acknowledged and informed the controller that he would head to M41 if his engine continued to operate, but it failed a second and final time about 5 minutes after restart.

The controller asked the pilot if he was familiar with highway 78, which the pilot acknowledged and reported the highway was in sight. He also informed the controller that his carburetor heat was “all the way out.” During approach to the highway, the airplane cleared a bridge, but the airspeed was degrading, and he was not sure if he would clear the second bridge. He decided to land on the left side of the road prior to the second bridge and attempted to avoid a concrete structure; however, during the landing, the airplane bounced then struck terrain before flipping over and coming to rest inverted.

Examination by a Federal Aviation Administration (FAA) inspector revealed that the airplane was substantially damaged during the impact. Both wings were deformed, and the right wing was folded down about 12 inches outboard of the wing strut, damaging the wing spar. The nose landing gear was sheared off and there was damage to the bottom of the engine compartment and multiple buckles in the airframe. The two-blade metal propeller was undamaged, and the spinner was crushed uniformly. In addition, about 18 gallons of fuel was recovered from the airplane (13 gallons in the left tank and 5 gallons in the right tank and fuel was observed in the fuel bowl).

A more comprehensive examination confirmed crankshaft continuity through 720° of rotation, with observed thumb compression on all cylinders. All spark plugs were removed and examined; they all exhibited normal wear and were light gray in color when compared to the Champion Check-A-Plug Chart. About 6 quarts of oil was observed in the engine and the oil filter presented no evidence of foreign material or blockages. Both left and right magneto input drives were rotated and produced spark on all towers. Fuel was observed in the gascolator and carburetor and no anomalies were observed in the functionality of the carburetor or fuel accelerator pump. No water was detected in any of the systems. The fuel selector functionality was confirmed. The carburetor heat control was in the ON position and remained attached to the carburetor heat box. The examination of the wreckage and engine revealed no evidence of any preimpact mechanical anomalies that would preclude normal engine operation or airplane performance.

According to the FAA Special Airworthiness Information Bulletin (SAIB) CE-09-35 Carburetor Icing chart, weather conditions at the time of the accident were conducive to the formation of serious carburetor icing at cruise power settings.

Special Airworthiness Information Bulletin (CE-09-35) – Carburetor Icing Prevention, stated that:

…pilots should be aware that carburetor icing doesn't just occur in freezing conditions, it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity. Icing can occur in the carburetor at temperatures above freezing because vaporization of fuel, combined with the expansion of air as it flows through the carburetor, (Venturi Effect) causes sudden cooling, sometimes by a significant amount within a fraction of a second. Carburetor ice can be detected by a drop in rpm in fixed pitch propeller airplanes and a drop in manifold pressure in constant speed propeller airplanes. In both types, usually there will be a roughness in engine operation.