N2591VCessna 177RG · 1974

On July 30, 2022, about 0800 Pacific daylight time, a Cessna 177RG, N2591V, sustained substantial damage when it was involved in an accident near Livermore, California. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight.

The pilot departed Salinas Airport (SNS), Salinas, California, en route to Livermore Municipal Airport (LVK) after an uneventful prefight check and engine runup. About 30 minutes after takeoff, he noticed that the engine monitor was indicating an increase in EGTs for all cylinders. The engine then briefly “stuttered,” and he decided to divert to an airport en route for a precautionary landing. He then adjusted the fuel mixture control, and the temperatures returned to normal, so he decided to continue to the original destination. About 10 minutes later, he initiated the landing descent to LVK by reducing engine power and moving the fuel mixture to full rich.

During the landing approach, the EGTs again began to rise, and the engine lost all power. The airplane sustained substantial damage to the left wing and stabilator after landing short of the runway and striking a set of instrument landing system lights.

Postaccident examination did not reveal any anomalies with the engine or airframe, and the engine could be operated at varying speeds during a ground run. Review of the data recorded by the airplane’s engine monitor indicated that the EGT rise was about 200° F, and during the periods of EGT rise, there was no discernible change in fuel flow. (The fuel flow transducer was installed at the inlet of the fuel injection servo, rather than the outlet to the flow divider.)

The airplane was equipped with a Bendix RSA-5AD1 fuel injection servo. The servo and flow divider were tested and examined at Precision Airmotive’s facility. The testing revealed that both units met the performance specifications required following a field overhaul.

However, disassembly of the fuel injection servo revealed significant internal corrosion and corrosion deposits throughout. The diaphragm cavities displayed “water lines” and corrosion on the metered and unmetered fuel sides, consistent with water contamination (figures 1 and 2). Corrosion deposits were present in the servo valve seat cavity and in the mixture control assembly (figures 3 and 4).

Figure 1 - Water line and corrosion on metered side

Figure 2 - Water line and corrosion on unmetered side

Figure 3 - Corrosion deposits on the lower side of the mixture control spring

Figure 4 - Corrosion on the surfaces of the idle and mixture valve housing bore

Precision Airmotive Service Bulletin PRS-97, revision 2, issued in August 2013, stated that the time between overhaul (TBO) for all fuel injection system components is either the same as the TBO specified by the engine manufacturer for the engine or 12 years since placed in service or last overhauled, whichever occurs first. The bulletin also stated that an overhaul is mandatory if the fuel system is contaminated with water.

Maintenance records indicated that the last rebuild of the fuel injection servo was performed in August 1999, 23 years before the accident while the engine was undergoing an overhaul. Another engine overhaul was performed in August 2012, and the corresponding logbook entry stated that no accessories were overhauled at that time.

The maintenance logbooks did not indicate the fuel system had been exposed to water; however, examination of the airplane indicated that the gascolator had recently been replaced. There was no maintenance entry to reflect this work, and the mechanic who performed the most recent annual inspection stated that he did not replace the gascolator at that time. There were no significant periods of inactivity noted in the logbook, although the owner stated that the airplane sat idle for 6 months before he purchased it in June 2020. He stated that the airplane was kept in a hangar for much of its recent life.