N9748Y

On August 07, 2025, at 1532 Pacific daylight time, a North American T-28C, N9748Y, was substantially damaged when it was involved in an accident near West Wendover, Utah. The pilot and the passenger were seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The passenger stated that they had arrived earlier in the week for Bonneville Speed Week and the purpose of the accident flight was to return home. Prior to departure they received full fuel, and the pilot started the engine, letting it run at idle while waiting for a helicopter to depart. They departed to the southeast and the pilot initiated a gradual climb. The pilot then began a right turn to head west toward mountainous terrain.

At an estimated 700–800 feet above ground level, the airplane began to shudder, which the passenger described as feeling the vibration emanating from the front of the airplane. He did not recall any reduction in power after takeoff, and he did not smell fuel, oil, smoke, or anything unusual, nor did he hear any abnormal sounds. As the shuddering worsened, the pilot continued the right turn, which the passenger interpreted as an attempt to return to the airport. When the airplane was heading back toward the airport, the vibration became severe.

The airplane descended and impacted the ground hard, bouncing several times before coming to rest about 1.5 miles from the airport. Dust immediately filled the cockpit, obscuring his view of the pilot. The pilot was bleeding from a head wound, but regained responsiveness after a couple of minutes. Both occupants had worn seat belts, but did not wear helmets.

The airplane was manufactured in 1956 by North American as model T-28C, and was designated serial number 140551. The airplane was powered by a Wright R1820-86B 9-cylinder radial engine rated at 1,425 horsepower and equipped with a Hamilton Standard 3-bladed constant speed propeller.

Investigators conducted a post-accident examination at the recovery facility. Oil had coated the left side of the airplane, with the origin at the engine breather tube (see figure 1 below).

Figure 1: Airplane after accident (picture provided by Federal Aviation Administration inspector)

An external examination of the engine revealed no evidence of an uncontained failure. Oil was observed lightly coating cylinders Nos. 1, 2, 3, and 4. The No. 4 cylinder pushrods were bent with the pushrod housing nut on the exhaust valve displaced (see figure 2 below).

Figure 2: Cylinder No. 4 push rods (bent)

Removal of the forward spark plugs revealed that cylinders Nos. 4, 6, and 7 were oil-soaked. The No. 6 forward spark plug was not torqued in the cylinder bore and was loose to rotate out of the cylinder. Investigators were unable to rotate the engine by applying force on the propeller blades. Investigators removed cylinder No. 4, providing an internal view of the crankcase. The articulating rods for Nos. 4, 5, and 6 were fractured at the master rod end. The corresponding cylinder skirts were damaged with grooves similar in dimension to the respective articulating rod, consistent with repeated contact between the skirt wall and the broken rod in the same plane. The articulating-rod journals on the master rod were not oil-covered (dry). The counterweights showed gouges on the outer portion of the shoe. Metallic debris was present on the aft side of the pistons and throughout the case.

The cylinder No. 4 articulating rod remained attached to the piston pin (see figure 3 below). The No. 4 piston face was dark with carbon, consistent with normal operation. The valves appeared normal with no evidence of piston-to-valve contact. The valve reliefs on the exhaust valve displayed a gouge consistent with the radius. The No. 4 piston was stuck in place and could not be freed.

Figure 3: Cylinder No. 4 articulating rod

The oil reservoir tank contained only a trace amount of oil with slight metallic debris on the bottom. The Cuno oil filter was removed and revealed fine metallic particles. The high-pressure oil strainer screen was removed and revealed coarser metallic particles (see figure 4 below). The metallic debris was both ferrous and non-ferrous, with mostly non-ferrous debris, indicative of aluminum, and there was additionally gold color flecks. The airplane was not equipped with an after-market “clean kit” or Whittaker valve, nor was it required.

Figure 4: The oil filter and oil screen metallic contents

The oil sump pump was removed; the gears were intact, and rotational scoring was noted on the gear vanes and surrounding housing with metallic particles present. The sump chip detector was coated with metallic particles. The chip detector on the supercharger had fine particles, but the screen was clean. Continuity was obtained on both chip detectors. The oil chip light in the cockpit was intact with no stretch noted in the filament. Continuity was obtained between the light and the cannon plug to the sump gear detector, indicating that it would have been operational. The oil shutoff poppet valve and spring on the oil pump housing appeared intact and operational.