NTSB Factual Report

On March 18, 2008, about 1055 mountain standard time, a Cessna 150L, N19521, collided with trees during a forced landing at Mesa, Arizona. Arizona Aviation was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certified flight instructor (CFI) and the student pilot sustained minor injuries. The airplane sustained substantial damage to the wings and fuselage. The local instructional flight departed Mesa about 1040. Visual meteorological conditions prevailed, and no flight plan had been filed.

The CFI reported that the taxi, run-up, and the first two takeoffs and landings in the local traffic pattern were uneventful. On the third takeoff, the airplane climbed to around 75 feet above ground level, and then the engine sputtered. The CFI took control of the airplane from the student. He pulled the carburetor heat handle to the hot position and put the mixture selector in the full rich position. The airplane was slightly above 100 feet and did not produce enough power to maintain flight. As they descended for an off airport landing onto a street, a wing hit trees. The airplane spun around as it hit the ground. Both wings and the fuselage sustained substantial damage.

On April 1, 2008, a representative from Teledyne Continental Motors (TCM) conducted an examination of the engine components, under the supervision of a Federal Aviation Administration (FAA) inspector. The components had been transported from the accident site to Air Transport, Phoenix, Arizona, for storage and testing. Recovery personnel removed the airplane wings in order to transport the wreckage. They noted that the nose gear collapsed, and the front of the engine was on the ground.

The investigators noted that the bottom of the fuselage and horizontal stabilizer were stained with a substance similar in color, odor, and consistency with oil. The propeller had damage to the leading edge, including aft bending near the tips. There was also propeller spinner impact damage, which included longitudinal striations to the flattened area.

Investigators noted that the engine and engine accessories were intact; there was impact damage to the induction system. The crankcase split line contained a rubber-like material. The investigators removed the spark plugs and noted normal wear and dark sooty deposits when compared to the Champion Aviation Check-A-Plug Comparison Chart. A borescope inspection revealed deposits on the piston tops, cylinder heads, and valves. According to the engine manufacturer representative, the amount of deposits was above normal for the low time on the engine since last overhaul.

The TCM investigator removed the damaged propeller, and replaced it for the engine run. A container of fuel was attached to the left wing fuel line. The investigators noted that the mixture control bottomed out before reaching the full idle stop. They removed the air filter, and the throttle cable had to be straightened to allow normal actuation.

The investigators ran the engine without anomalies through operation at different ranges of power. They performed a magneto check, and noted that the engine ran rough on the left magneto. They shut the engine down, and all four cylinders were at temperatures that were consistent for normal operation.

The investigators performed a second engine run with only the left magneto operating. After they shut the engine down, the number one cylinder was cold when compared to the other cylinders. They disconnected the spark plugs from the ignition leads, and the investigator rotated the propeller by hand. All of the ignition leads produced a spark. The number one spark plugs were reconnected to their respective ignition leads. The number one bottom spark plug, which was connected to the left magneto, did not produce a spark when the propeller was rotated by hand. The investigator removed the spark plug, and observed that it was dark in color and coated with oil.

During a compression test performed by an FAA inspector, air was heard within the crankcase while there was pressure on the number four cylinder. After removal, the number four cylinder compression ring gaps were found in the same location on the piston. The investigator also found several cylinder base studs to be the improper size. According to the engine manufacturer representatives, the engine had a total time of 10,547.9 hours, and the time since the last major overhaul was 284.7 hours.

NTSB Probable Cause

A partial loss of engine power for undetermined reasons.