History of Flight
On April 10, 2023, at approximately 1759 eastern daylight time, a Cessna 152, registration N757YM, was substantially damaged during an accident near Danbury, Connecticut. The flight instructor and student pilot sustained minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as an instructional flight.
The student reported performing weight and balance calculations indicating 15 gallons of fuel onboard. The flight instructor later stated he used a fuel consumption rate of 5 gallons per hour, equating to about 3 hours of remaining fuel, but did not account for fuel used during engine start, taxi, or takeoff. The student performed a preflight inspection, including a fuel tank check with a dipstick, but could not recall the readings. The instructor indicated there was enough fuel for the flight but admitted he had not checked the tanks and could not recall the fuel gauge readings at engine start. The student performed an engine run-up before departure, which included checks of magnetos and carburetor heat, both operative; all instruments were functioning. The instructor asked her to check the fuel gauges but did not recall her reporting anything about them.
According to ADS-B data, the flight departed from runway 26 about 1601. The instructor stated that after takeoff they remained in the traffic pattern, performed a go-around, and a normal landing. They then departed the pattern for airwork practice, returned for more pattern work. After the third go-around, while on the downwind leg abeam the landing spot, the instructor took control to demonstrate a landing and turned onto base leg. While flying at 65 knots between 800 and 900 feet mean sea level, the engine began sputtering. He pitched down; the engine restarted briefly (about 2 seconds) then lost all power. He observed two high towers near the end of runway 26 and turned toward a grass field behind him. He performed a steep spiral to lose altitude. The airplane slowed, and the stall warning horn sounded. He moved the flap selector from 10° to 20° and braced for impact. The student reported the airplane struck a shed. Both pilots stated that an EMT told them they smelled of fuel after the accident.
Aircraft and Fuel Information
The airplane was modified with multiple Supplemental Type Certificates (STCs), including installation of a Lycoming O-235-L2C(M) engine and a Sensenich fixed-pitch propeller. The FAA Approved Airplane Flight Manual Supplement (AFMS) for the modifications stated rated rpm of 2,800 and 125 horsepower for all operations. The AFMS performance section noted increased fuel consumption relative to the original airplane flight manual.
According to the Airplane Type Certificate Data Sheet, total usable fuel capacity was 24.5 gallons, with 0.75 gallon unusable in each wing tank (total 1.5 gallons unusable). The Pilot's Operating Handbook specified that fuel consumed during engine start, taxi, and takeoff was 0.8 gallon. The engine Operator's Manual listed fuel consumption ranging from 9.5 gallons per hour at normal rated power to 5.8 gallons per hour at 65% rated power.
Fuel records indicated 16.6 gallons of 100 low-lead fuel were added on the morning of the accident, filling the tanks. Operator records showed that between fueling and the accident flight, the airplane flew 3 flights totaling 3.1 hours. The accident flight lasted 2.2 hours according to the hour meter, so the airplane had flown a total of 5.3 hours since last fueling.
Wreckage and Impact Examination
According to the FAA inspector, the airplane impacted a residential area about 1 mile east of Danbury Municipal Airport (DXR). The right wing struck near the roof line of a house adjacent to a shed, then impacted the shed. No post-impact fire occurred. The airplane came to rest listing to the right. No fuel was drained from the left fuel tank (nearly vertical), and about 1.7 gallons were drained from the right fuel tank.
Examination of the fuel system after recovery revealed broken fuel supply lines in the cockpit area, but no blue stains were present. The fuel supply line to the airframe fuel strainer was kinked; the bowl separated from the firewall and contained about 40 milliliters (about 1 ounce) of fuel. The carburetor bowl contained no fuel. Both fuel caps were vented and had no discrepancies. No pre-impact discrepancies other than impact damage were found in the fuel supply lines. Due to impact damage, the fuel gauges could not be electrically checked.
Postaccident examination of the engine found no evidence of pre-impact failure or malfunction of the powertrain, ignition, air induction, or exhaust systems. Throttle and mixture control continuity was confirmed from the cockpit to the carburetor. The propeller blades had no nicks on leading or trailing edges, and no scoring on cambered sides or blade faces; one blade had a slight aft bend.