Glen Saint Mary, FL, USA
N53269
Cessna 172S
The certified flight instructor (CFI) and student pilot departed on an instructional flight and when the CFI reduced throttle to demonstrate a power-off stall to the student, the engine experienced a loss of power, but the propeller continued to windmill. Attempts to restore engine power were unsuccessful and the CFI maneuvered the airplane towards a nearby field. The airplane was landed in the field before a row of trees and collided with them during the landing roll. Two weeks before the accident the engine "...cut out on round out at Fernandina Airport." The corrective action performed by maintenance personnel included adjusting the idle speed and the idle mixture. The CFI reported that on several previous occasions when flying the accident airplane, the engine experienced a loss of power when the throttle was reduced. . Postaccident examination of the airplane revealed a sufficient quantity of fuel. During an engine run in a test cell at the manufacturer's facility the engine lost power when the throttle was reduced below 1,500 rpm. The engine was only able to sustain operation at low power settings by manually leaning the fuel to air ratio. Examination of the servo fuel injector (servo) at the manufacturer's facility following the engine run revealed a plastic sleeve was missing/separated from the idle stop. Bench testing of the servo at the manufacturer's facility revealed with the throttle at the idle stop and the mixture control in the full rich position, the airflow in terms of pounds-per-hour was 6.0 instead of 100.0, and the fuel flow was 1.2 pph instead of 6.0 to 7.0 pph. Further bench testing of the servo revealed the fuel flow at 4 of the test points exceeded specified limits, while the fuel flow was within limits at 2 of the test points. No determination could be made as to when the plastic sleeve separated from the idle stop.
On July 2, 2005, about 1314 eastern daylight time, a Cessna 172S, N53269, registered to Fly Magic, Inc., operated by DreamCatcher Aviation, Inc., experienced a loss of engine power while maneuvering and collided with trees, during a forced landing in a field near Glen Saint Mary, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 local, instructional flight from Herlong Airport, Jacksonville, Florida. The airplane was substantially damaged and the certified flight instructor (CFI) and student pilot sustained minor injuries. The flight originated about 1230, from Herlong Airport. The CFI stated that he performed a preflight inspection using the airplane's checklist; no discrepancies were reported. The flight departed with approximately 40 gallons of fuel on board and proceeded west where the flight climbed 2,500 feet. The student performed several maneuvers, and when asked to demonstrate a power-off stall, was unsure how to perform the maneuver. The CFI elected to demonstrate the maneuver to the student, and he performed a cockpit check which included confirming the fuel shutoff valve was in the on position or "in", the fuel selector valve was in the "both" position, verified the circuit breakers were in, the engine gauges were in the green, and checked the annunciator panel. He initiated the maneuver by reducing power to 1,500 rpm, and extended the flaps to 30 degrees. When the airplane was at 60 knots, he reduced power to simulate flare. At that time, the engine experienced a loss of power; however, the propeller continued windmilling. He pitched the airplane to maintain 68 to 70 knots, retracted the flaps, and noted the engine rpm was in the "idle rpm" range, and the throttle control felt "loose". He attempted to restart the engine but was unable. While descending he maneuvered the airplane towards a field, and while descending and approaching it, saw unmarked power lines. He added 30 degree of flaps, and cleared the power lines. Before touchdown, he told the student to open his door. The airplane was landed in the approximately 1,500-foot long square field approximately 10 feet before a row of trees. The airplane collided with trees and came to rest. With respect to the throttle control, he reported it felt "freer" than normal. Postaccident examination of the airplane and engine were performed by representatives of the airplane and engine manufacturer with FAA oversight. The examination of the airplane revealed the fuel selector was in the "both" position. Approximately 17-18 gallons of fuel were drained from each main fuel tank; the gascolator bowl was broken. Continuity of the engine controls from the cockpit to engine was confirmed. The engine was sent to the manufacturers facility for an attempted engine run. With NTSB oversight in preparation of an engine run, the upper and lower vacuum pumps were removed. The engine was placed in a test stand with a test club propeller installed and the engine could not be rotated by hand. A lubricant was sprayed into all cylinders and the engine was able to be partially rotated by hand but impact damage to the propeller flange was noted. The propeller flange was straightened and 360-degree rotation of the engine by hand was obtained. The engine was then started but ran rough. The engine run was terminated and the bottom spark plugs were removed; the No. 3 cylinder bottom spark plug was cleaned after noting it was contained a large amount of rust and debris. High tension testing of the ignition harness revealed the top ignition leads for the Nos. 1 and 2 cylinders failed. Both ignition harnesses were replaced and the engine was restarted but quit when the throttle was reduced below 1,500 rpm. The fuel injector nozzles were inspected and found to be free of obstructions. Simultaneous flow testing of the entire fuel injection system revealed the quantity of fuel flowed from each fuel injector nozzle visually appeared to be the same. The engine was restarted and when the throttle was reduced below 1,500 rpm, the engine would only remain running by manually leaning the mixture from the full rich setting to a fuel flow rate of approximately 5.8 pounds-per-hour (pph). The engine was documented to obtain rated power with the test club propeller installed (2,402 rpm). Fuel injection components consisting of the servo fuel injector (fuel servo), 4 fuel injector nozzles, and flow divider were removed from the engine and sent to the manufacturer's facility for further examination. Examination of the fuel servo, 4 fuel injector nozzles, and flow divider was performed at the manufacturer's facility with FAA oversight. Visual examination of the fuel servo revealed the throttle lever was bent slightly, the unit was blackened in the throat, and a "...plastic sleeve is broken off the idle stop." Bench testing of the fuel servo as received was performed using production testing standards. The bench testing revealed that with the throttle at the idle stop and the mixture control placed at the full rich position, the recorded airflow in terms of pounds-per-hour (pph) was 6.0 pph instead of 100 pph, and the fuel flow at that setting was 1.2 pph (fuel flow specification at idle stop and 100 pph airflow is 6.0 to 7.0 pph.) Further bench testing of the fuel servo as received revealed the fuel flow rates in terms of pph were greater than specified at test points 1, 6, 7, and 11. The unit flowed within pph fuel flow limits at test points 8, and 10. The idle settings were then adjusted and the unit was again bench tested and the fuel flow pph were within specified limits at test points 3, 6, and 10. The unit exceeded fuel flow pph limits at test points 1, 7, 8, and 11. A review of the airplane "Discrepancy Form" revealed an entry dated June 18, 2005, which indicates that the engine "cut out on round-out @ Fernandina Airport." A sales invoice dated June 22, 2005, for a Jacksonville, Florida, maintenance company indicates 1.0 hour labor to "Adjusted idle and idle mixture." There was no record of this work performed in the permanent maintenance records. The airplane and all NTSB retained components were released to Chris Dannecker, of CTC Services Aviation (LAD, Inc.,) on May 22, 2006.
The separation of a plastic sleeve off the idle stop of the servo fuel injector for undetermined reasons resulting in decreased fuel flow and subsequent total loss of engine power.
Source: NTSB Aviation Accident Database
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