N1235U

On October 20, 2021, about 1615 central daylight time, a Cessna 210N airplane, N1235U, sustained substantial damage when it was involved in an accident near Dallas, Texas. The airline transport pilot sustained no injuries. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 business flight.

The pilot reported that during the takeoff, he felt and heard a fluctuation in the engine power. The fuel flow monitor showed about 148 pounds per hour and then showed only “dashes” on the monitor. The pilot initiated a descent to abort the takeoff at which time the engine returned to full power. He concluded that the engine power fluctuation had only been for a few seconds, and he did not notice a fluctuation on the cylinder head temperature monitor.

During the landing, the nosewheel impacted the runway first, and the tire was blown. The airplane rolled off the runway, impacted a shallow ditch, and came to rest inverted on a grass field. The pilot performed an emergency shutdown and was able to egress from the airplane without further incident. The airplane sustained substantial damage to the fuselage, the left wing, and the empennage.

A postaccident examination of the airframe and engine was performed. Both fuel tanks and the fuel lines appeared to be free of any contaminants. Fuel was drained from the airframe and appeared to be light blue in color and free of any contaminants. The fuel strainer was opened, and an unknown white substance was noted. Small specks of white contaminants were found in the gascolator.

The fuel pump was removed, and bench tested normally. Teardown revealed internal damage to the pump rotor and the thrust plate. The diaphragm was found to be in a stiff condition. No containments were found inside of the fuel pump and the source of the internal damage to the fuel pump could not be determined.

The pilot reported that the airplane had previous fuel fluctuation issues and the pilot found “very fine sand like material” in previous fuel samples. The pilot theorized that the previous contaminants found could have been from residue from previous maintenance work where the fuel tanks were sealed. During a previous inspection, a mechanic noted that, “inspection of the upper wing fuel tank access plates shows that improper sealant was used in their installation.” However, additional information of the type of sealant previously used in the fuel tanks was not available.

Continental Motors has published Service Bulletin (SB) 08-4A Fuel Injection System Contamination. This document states in part:

It is imperative that fuel injection system components be kept free from contamination during all installation and maintenance procedures.

Fuel system contamination may lead to fuel system component damage, erratic engine operation, loss of power, or engine shutdown.

A review of the airplane’s maintenance records showing recent maintenance work prior to the accident, did not show any annotation of SB 08-4A being complied with, even though the fuel injection system was worked on. The Federal Aviation Administration does not mandate compliance with service bulletins for 14 CFR Part 91 operations.

Aircraft Maintenance Technology has published a magazine article titled, “Continuous Flow Fuel Injection Systems.” This article discusses Continental Motors fuel injection systems and states in part:

Many TCM fuel system failures can be attributed to contaminates that have entered the system. These contaminants range from shaved “O” rings to fuel bladder material. “Foreign objects” always seem to migrate to the worst possible spots.