Primary finding
Probable cause
A loss of engine power due to the separation and ingestion of an air filter retaining bracket into the engine cylinder.
Investigator assessment
Analysis narrative
The pilot reported that about 40 ft above ground level (agl) during the initial climb from the grass airstrip, engine cylinder Nos. 2 and 3 lost power. About 10 seconds later, engine cylinder Nos. 1 and 4 lost power. The pilot was unable to maintain altitude. He switched fuel tanks in an attempt to regain engine power but noted no change in the engine performance. The airplane impacted trees beyond the departure end of the runway and sustained substantial damage to both wings, fuselage, and empennage. Postaccident examination of the engine revealed an air filter retaining bracket that was fastened to a fiberglass air snorkel/box had separated and was ingested into the No. 2 cylinder. The separated bracket then jammed the intake valve into the open position, resulting in a loss of engine power. Elongation was noted on the fiberglass where the rivets secured the fabricated retaining bracket.
Source record
Factual narrative
On August 14, 2024, about 2021 central daylight time, a Vans RV-8A airplane, N184DC, sustained substantial damage when it was involved in an accident near Guthrie, Oklahoma. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, about 40 ft agl during the initial climb from the grass airstrip, engine cylinder Nos. 2 and 3 lost power. About 10 seconds later, engine cylinder Nos. 1 and 4 lost power. The pilot was unable to maintain altitude. He switched fuel tanks in an attempt to regain engine power but noted no change in the engine performance. The airplane impacted trees beyond the departure end of the runway. The airplane sustained substantial damage to both wings, fuselage, and empennage. Postaccident examination of the engine revealed no compression was noted on the No. 2 cylinder. The air filter was removed from the fiberglass air snorkel/box, and one of the four fabricated retaining brackets was separated and missing (see Figure 1). Elongation was noted on the fiberglass where the rivets secured the fabricated retaining bracket. Figure 1. Air filter retaining brackets; one bracket separated and missing. The No. 2 cylinder intake tube was removed, and a foreign metal piece, consistent with the separated retaining bracket, was observed within the cylinder. The bracket was jammed in the cylinder and under the intake valve seat. The intake valve and retaining bracket were removed from the cylinder and photo documented (see Figures 2 and 3). Figure 2. No 2. cylinder intake and separated retaining bracket. Figure 3. Separated air filter retaining bracket located in the No. 2 cylinder intake.