N330PC

On February 6, 2023, at 1432 central standard time, an experimental amateur-built RV-6, N330PC, was substantially damaged when it was involved in an accident near Milton, Florida. The airline transport pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to the pilot, he was relocating the airplane following completion of its annual condition inspection. He reported performing a thorough preflight inspection that included sampling the fuel, with no contaminants noted, checking the oil, which was full at 8 quarts, and checking the tires and brakes, which were new. He also reported that the left fuel tank was indicating about 7 gallons of fuel and the right fuel tank was almost full. Nothing abnormal was observed during the preflight, engine start, or run-up and taxi. The pilot reported he positioned the fuel selector to the right fuel tank before taxiing to the runway. Shortly after takeoff, during the initial climb about 300 to 400 ft mean sea level, the engine “let out a muffled, sucking backfire” and sustained a total loss of power that was confirmed by multiple eyewitnesses. The pilot pushed the nose over abruptly to maintain airspeed and made a mayday radio call reporting the loss of engine power over the airport’s common traffic advisory frequency. During descent, the engine regained power shortly before the airplane impacted the ground. A witness was taking a video recording of the airplane during the flight and the video cofirmed the increase in engine power several seconds before impact.

The airplane impacted the ground and a fuel truck before coming to rest. There was no postimpact fire. Postaccident examination confirmed the fuselage, tail section, and wings were substantially damaged. The right wing was mostly intact and the left wing was crushed from impact with the ground and fuel truck. The right fuel tank remained intact and contained about 9 gallons of fluid consistent in color and odor with 100LL aviation fuel and no contaminants were noted. The left fuel tank was breached but contained residual fuel.

Postaccident examination of the engine yielded no anomalous damage or pre-impact failures or irregularities in the engine or its subcomponents.

Photographs showed the fuel pickups in the wings remained secured in place and the left fuel pickup exhibited impact damage. The fuel selector was in the left position and liquid with an odor consistent with 100LL aviation fuel was observed in the engine-driven fuel pump, fuel servo, the hose from the servo to the flow divider and in the flow divider. The fuel strainer screen was removed and exhibited minimal debris. Both the electric fuel boost pump and engine-driven fuel pump were examined and operated normally with no anomalies noted. The fuel injector servo remained attached to the engine and examination revealed no damage or anomalies. The servo fuel regulator section was partially disassembled and no damage to the rubber diaphragms or other internal components was observed, and the injectors were free of any obstructions. The throttle control cable remained attached to the throttle control arm, which remained attached to the servo. The mixture control cable remained attached to the servo mixture control arm. The mixture control cable was impact separated at the rod end and the rod end remained attached to the servo.

The propeller and flange were impact separated from the engine and exhibited signatures consistent with torsional overload. One propeller blade was rotated about 90° in the hub such that the leading edge faced forward and was curled aft beginning about 1 ft from the tip and also exhibited trailing edge “S” bending, spanwise twisting, chord-wise abrasion, and leading-edge gouges. The opposing propeller blade was curled aft beginning about 8 inches from the tip and exhibited spanwise twisting, chord-wise abrasion, and leading-edge gouges. The propeller governor remained attached to the engine and no damage was noted. The governor drive assembly was rotated freely by hand. The governor oil screen was absent of debris.

The fuel pickup in both wing tanks were not installed correctly when compared to the plans for a Van’s Aircraft RV-6. The plans called for the fuel pickups to be routed down towards the bottom of the fuel tank and then bend toward the aft bulkhead of the fuel tank, under the fuel sending unit. The fuel pickups on the accident airplane were routed down and then bent forward toward the leading edge (see figure 1). The kit manufacturer reported that if the fuel pickups were bent forward toward the leading edge instead of aft, as the plans called for, then the amount of unusable fuel would greatly increase. The pilot (who was the third owner of the airplane and not the original builder) reported that there was no documentation stating the amount of unusable fuel, only that the fuel tanks had a total capacity of 38 gallons. The investigation was not able to determine the amount of unusable fuel due to the selected fuel tank being compromised in the accident sequence. A “Flying Lessons” article published by the FAA on May 26, 2011, discussed how fuel moving away from the fuel tank pickups could result in fuel starvation and a loss of engine power.

Figure 1 - Fuel pickup position on accident airplane with RV-6 plan schematic showing the proper configuration.

A review of maintenance records showed that service bulletin SB 06-2-23 and a service notification letter issued June 12, 2000, from the kit manufacturer, relating to the fuel pickups, had not been complied with. The publication Service Bulletins and the Aircraft Owner, published by the FAA, states, “Manufacturers issue aircraft Service Bulletins to inform owners and operators about critical and useful information on aircraft safety, maintenance, or product improvement,” and, “If you are operating your aircraft under 14 CFR part 91, a service bulletin is advisory, and compliance is not mandatory unless it is included in an Airworthiness Directive.” A search of the FAA Dynamic Regulatory System found no airworthiness directives for the Van’s Aircraft Inc. RV-6.