Pilot Debrief

SILVAIRE LUSCOMBE 8A near New Port Richey, FL — 2025-03-27

Final reportERA25LA159
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Date
2025-03-27
Location
New Port Richey, FL, USA
Aircraft
SILVAIRE LUSCOMBE 8A
Registration
N28790
Category
Airplane
Highest injury
None
Fatalities
0

Probable cause

Maintenance personnel’s inadequate inspection of the exhaust system, which allowed exhaust gases to enter the induction system from cracks in the exhaust manifold, resulting in a total loss of engine power and a subsequent forced landing.

NTSB narrative

The airplane had recently undergone significant maintenance, including an engine overhaul, airframe reassembly, and an annual inspection. The accident flight was the third flight after the maintenance was completed. While flying at an altitude of 800 ft, the pilot reported a total loss of engine power. The pilot attempted to restart the engine but was unsuccessful. The pilot performed a forced landing in a grassy area, and during the landing, the airplane struck a rut in the grass and flipped over, resulting in substantial damage to the vertical stabilizer, the rudder, the horizontal stabilizer, and the left wing. Postaccident examination of the wreckage revealed that the spark plugs and internal portions of the cylinders were dark and soot-covered. This was consistent with an overly rich mixture during engine operation. Further examination of the airplane revealed that the exhaust system was severely corroded, with metal thinning at multiple locations and was porous in other locations. The portions of the exhaust system that were within the carburetor heat shroud displayed cracks that contained exhaust deposits, and there were exhaust deposits within the carburetor heat shroud. This is consistent with the cracks being present prior to the accident, and allowing exhaust gases to enter the carburetor heat system. Even if the carburetor heat was off at the time of the loss of power, some of the exhaust gases would still be able to enter the engine’s induction system, which would result in an enrichment of the fuel/air mixture. It is likely that during the test flight, sufficient exhaust gases entered the induction system, making the fuel/air mixture overly rich and resulting in the loss of engine power. The airplane’s most recent annual inspection had been completed less than a month prior to the accident, and the airplane had flown for only about 2.5 hours since then. It is unlikely that the observed corrosion occurred within that short period. While the mechanic reported that he didn’t believe that the exhaust was in that condition at the time of the annual inspection, the pilot confirmed that the exhaust had not been changed since the annual inspection. Given this information, it is likely that the mechanic failed to properly inspect the exhaust during the inspection and reassembly process. Had the mechanic performed a proper inspection, he would have found the exhaust in an unairworthy condition.

NTSB coding

Evidence available

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  • 9 docket documents
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Docket documents9

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