Accident Narrative
On October 20, 2021, at approximately 1615 central daylight time, a Cessna 210N airplane, registration N1235U, sustained substantial damage in an accident near Dallas, Texas. The airline transport pilot, who was the sole occupant, reported no injuries. The flight was conducted as a Title 14 Code of Federal Regulations Part 91 business flight.
The pilot stated that during takeoff, he felt and heard a fluctuation in engine power. The fuel flow monitor initially indicated about 148 pounds per hour, then displayed only dashes. The pilot initiated a descent to abort the takeoff, at which point the engine returned to full power. He noted the power fluctuation lasted only a few seconds and observed no corresponding fluctuation on the cylinder head temperature monitor.
During the subsequent landing, the nosewheel struck the runway first, causing the tire to blow. The airplane departed the runway, impacted a shallow ditch, and came to rest inverted on a grass field. The pilot performed an emergency shutdown and egressed without further incident. Substantial damage was reported to the fuselage, left wing, and empennage.
Postaccident Examination
A postaccident examination of the airframe and engine revealed that both fuel tanks and fuel lines appeared free of contaminants. Fuel drained from the airframe was light blue and uncontaminated. When the fuel strainer was opened, an unknown white substance was noted, and small specks of white contaminants were found in the gascolator.
The fuel pump was removed and bench-tested normally. However, teardown revealed internal damage to the pump rotor and thrust plate. The diaphragm was in a stiff condition. No contaminants were found inside the fuel pump, and the source of the internal damage could not be determined.
Previous Issues
The pilot reported that the airplane had experienced previous fuel fluctuation issues. He had previously found “very fine sand like material” in fuel samples and theorized that the contaminants might have originated from residue left during previous maintenance work when the fuel tanks were sealed. During an earlier inspection, a mechanic noted that “inspection of the upper wing fuel tank access plates shows that improper sealant was used in their installation.” Additional information on the type of sealant used was not available.
Maintenance Context
Continental Motors Service Bulletin (SB) 08-4A, titled “Fuel Injection System Contamination,” states that fuel injection system components must be kept free from contamination during installation and maintenance. It further notes that fuel system contamination may lead to component damage, erratic engine operation, loss of power, or engine shutdown.
A review of the airplane’s maintenance records showed that recent work on the fuel injection system did not include annotation of compliance with SB 08-4A. The Federal Aviation Administration does not mandate compliance with service bulletins for Part 91 operations.
Additionally, a magazine article titled “Continuous Flow Fuel Injection Systems” published by Aircraft Maintenance Technology discusses Continental Motors fuel injection systems and states that many such system failures can be attributed to contaminants entering the system, including shaved O-rings and fuel bladder material. It notes that foreign objects always seem to migrate to the worst possible spots.