Accident Sequence
On June 15, 2019, at approximately 0932 Pacific daylight time, a Cessna 182M airplane, registration N777RK, was substantially damaged during a forced landing near Cable Airport (CCB) in Upland, California. The private pilot and two passengers sustained serious injuries. The flight was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
The pilot reported that during the initial climb, as the airplane ascended through approximately 250 feet above ground level, the engine began to sputter. The pilot initiated a left turn to return to the airport. Shortly thereafter, the engine lost all power, and the pilot executed a forced landing to an open area south of the departure runway on airport property. The pilot indicated that he intended to land hard to break both landing gear legs off so the airplane would slide to a stop; however, the airplane bounced upon landing, became airborne, crossed a road, and came to rest upright in a parking lot after impacting trees.
Aircraft Examination
Local law enforcement examination revealed that the left wing had separated and the fuselage suffered structural damage. The airplane was recovered for further examination.
The Continental Motors O-470-R engine was examined. Compression was present on all cylinders except the No. 2 cylinder. Internal inspection of the No. 2 cylinder via a lighted borescope and subsequent removal showed scuffing throughout the sides of the piston.
The airplane was equipped with an engine monitoring unit. Data from the accident flight was downloaded, spanning 1 minute and 42 seconds at a 6-second sample rate, from takeoff power application to the last recorded data point. When takeoff power was applied, rpm, manifold pressure, and fuel flow increased. Fuel flow reached a maximum of 14.5 gallons per hour (GPH) at 16:23:02 unit time, then decreased briefly for 12 seconds before reducing significantly 24 seconds later. Data for the two flights prior to the accident showed that the No. 2 cylinder head temperature exceeded 460°F on both flights, which is the maximum allowable per the Continental owner's manual for the O-470-R.
Using the engine performance chart, the calculated fuel flow at takeoff power should have been approximately 22 GPH. The carburetor was examined under FAA supervision; due to damage to the throttle shaft, fuel flow measurements could only be obtained at full throttle, where the flow rate was slightly higher than optimal (slightly rich condition).
The FAA's Pilot's Book of Aeronautical Knowledge notes that an overly lean mixture can cause detonation, which may result in rough engine operation, overheating, and/or loss of power. Detonation is defined as an uncontrolled, explosive ignition of the fuel-air mixture, leading to excessive temperatures and pressures, and can cause piston, cylinder, or valve failure, as well as engine overheating, roughness, or loss of power. Common operational causes include use of lower fuel grade, operation with high manifold pressure at low rpm, and high-power operation with an excessively lean mixture.