Accident Overview
On September 17, 2017, at approximately 1347 Pacific daylight time, a Piper 28-161 airplane, registered as N2587X, lost engine power while on downwind for runway 27L at Gillespie Field Airport (SEE) in El Cajon, California. The certified flight instructor (CFI) sustained minor injuries, and the pilot-rated passenger was uninjured. The left wing sustained substantial damage. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight had originated from Gillespie Field at about 1250.
Flight Details
The pilot reported that after flying in the area, they returned to the airport to practice touch-and-go landings. The first two left-traffic touch-and-goes were uneventful. After the third takeoff, air traffic control directed them to make right traffic. While on downwind, they were cleared to land; the pilot reduced power and began a descent. After turning base, the pilot increased power, but the engine did not respond and remained at idle. There was no change in engine noise, and the engine was not running rough. Both pilots manipulated the throttle several times without response; they also operated the primer with no effect. The pilot chose to land on a nearby road. During the descent, the airplane struck powerlines and a tree before impacting the roadway and sliding to a stop.
Postaccident Examination
A postaccident engine examination found no anomalies that would have precluded normal operation. The throttle and mixture controls moved freely throughout their ranges. The gascolator bowl, when removed, had a clear screen with no debris. The oil filter was opened and contained oil with no contaminants or debris. The spark plugs exhibited wear consistent with normal operation per the Champion check-a-plug chart. With the rocker covers removed and the propeller rotated by hand, spark occurred in proper firing order, and rockers moved at the correct times. Thumb compression was present on all cylinders except the number 2 cylinder, which revealed the intake valve was unseated due to impact damage. Boroscopic inspection of all cylinders showed normal operating signatures. The carburetor bowl was removed; the fuel screen was clear, but the bowl and the accelerator pump well contained no fuel. The floats were intact and undamaged. Air blown from the gascolator to the wing root and from the electric-driven fuel pump to the carburetor inlet confirmed all lines were clear of blockages and debris.
Weather Conditions
At the time of the accident, the weather at Gillespie Field reported a temperature of 25°C and a dewpoint of 15°C. Review of the carburetor icing probability chart, per FAA Special Airworthiness Information Bulletin CE-09-35, indicated that the airplane was operating in conditions favorable for the formation of serious carburetor icing at glide power. On-scene photographs showed the carburetor heat lever was in the off position.