N2994XCessna 177 · 1967

On November 27, 2022, about 1345 mountain standard time, a Cessna 177, N2994X, was substantially damaged when it was involved in an accident near Willow Spring, Arizona. The pilot and passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot stated that the purpose of the flight was to fly to Sedona, Arizona, for lunch. He departed Lake Havasu, Arizona, his home base, with a calculated 34 gallons of fuel. He had made the same flight on previous occasions and the airplane used about 12 gallons, which would leave a reserve of about 21 gallons upon his arrival; he planned to refuel in Sedona.

After departing about 1245, the airplane climbed to about 9,600 feet mean sea level (msl) for the en route portion of the flight. The airplane continued at that altitude for about 10 minutes and then the engine sustained a total loss of power. The pilot attempted to troubleshoot the loss of power by trying various mixture and throttle settings while preparing for an off-airport landing. He estimated the airplane had about 23 gallons of fuel at this time. The pilot initially planned on landing on a dirt road but was unable to align the airplane, so he selected a field that contained high brush. During the landing the pilot pulled back on the control yoke to slow the airplane and to avoid contacting a boulder. The airplane stalled and came to rest inverted in the field adjacent to the remote dirt road.

The airplane had amassed a total time of 3,804.96 hours. A review of the airplane’s logbooks revealed that the engine was overhauled in June 2022, equating to about 38 flight hours before the accident. In August, the engine was inspected after the pilot encountered an overspeed. The records indicated that the last maintenance performed was in October 2022, with the installation of an autopilot system and an upgraded engine monitoring system.

A postaccident examination revealed no evidence of leakage in the fuel system. The wings were removed from the airframe for recovery and inspection showed they were not breached. The fuel strainer was opened and about 3 ounces of liquid was captured in a clean glass jar. The liquid was consistent in color (blue) and odor with that of 100LL Avgas. The fuel line at the strainer was removed and pressurized air was directed from the right and left wing fuel ports. Air flowed through the selector, the reservoir, the fuel shut-off, and the strainer, escaping out the disconnected line. The strainer was attached to the firewall and the screen was clean. Taking off the fuel lines through the system resulted in trace amounts of fluid leaking out. The electric boost pump remained attached to the firewall. Investigators connected an auxiliary battery to the pump and could hear the pump clicking coinciding with feeling light puffs of air on the outlet, consistent with normal operation. The mechanical pump was removed and disassembled, revealing no anomalies. When the pump’s lever was manipulated up and down, suction could be felt in the inlet and pressure could be felt on the outlet.

Disassembly of the carburetor revealed that it contained trace amounts of fuel. The composite floats were removed and floated when placed in water. There was some small debris in the carburetor bowl.

The throttle cable was frayed and had stretched out of its housing (inner wire pulled from the swage). It could not be determined if the damage was a result of impact. It was attached to the carburetor arm and moved slightly when manipulating the control knob in the cockpit (full travel was not possible). The airframe was missing the required bracket needed to attach the throttle cable to the airframe; instead, it was attached in an indirect route (see Figure 1 below). The mixture control arm was separated from the mixture shaft and the shaft was bent.

Figure 1: Throttle Cable from Arm to Cockpit

The engine cylinders’ combustion chambers were examined through the upper spark plug holes with a lighted borescope. The combustion chambers remained mechanically undamaged and there was no evidence of foreign object ingestion or detonation. There was no evidence of valve to piston face contact. The gas path and combustion signatures observed at the spark plugs, combustion chambers, and exhaust system components displayed coloration that the Lycoming representative said was consistent with normal operation. There was no oil residue observed in the exhaust system gas path.

Investigators achieved manual rotation of the crankshaft by rotation of the crankshaft propeller flange. Thumb compression was established in all cylinders. Valvetrain continuity was observed, with about equal lift action at each rocker assembly. The accessory gears were undamaged and had a light residue of oil.

The magnetos remained attached to their mounting flanges. The magnetos were both timed to about 26°. The left magneto leads were removed and upon rotation of the propeller spark was observed at each lead. The right magneto was removed. Manual rotation of the magneto produced spark at every lead.

The oil filter and suction screen were secure at their respective mountings. The oil filter and suction screen were removed and examined. The oil filter was cut open to expose the filter media. Visually there was no evidence of pre-mishap metal contamination observed in the filter pleats. There was small sliver of fibrous material in the suction screen.

The air intake filter was dirt filled, which was consistent with impact. The Sceet ducting (air intake duct) extending from the air filter housing to the carburetor was partially crushed. Wear marks and red sealant were observed on both the tubing and the cowling. Corresponding marks were identified on the No. 2 exhaust tube. Modifications were evident on the air filter box involving the relocation of the tubing attaching flange.

The Cessna Service Manual states that the throttle control should be replaced at the engine time between overhaul (TBO), which was 2,000 hours for the accident engine.