History of Flight
On July 23, 2022, at 1331 Pacific daylight time, a North American T-28B, registration N787AS, was substantially damaged when it collided with a plant nursery near Fallbrook, California. The pilot sustained serious injuries and the pilot-rated passenger was fatally injured. The flight was conducted as a personal flight under 14 CFR Part 91.
According to a law enforcement officer's interview with the pilot immediately after the accident, the pilot and passenger had been friends for over 50 years and both had extensive aviation experience. Earlier that day, they departed from Chino, California, in separate airplanes: the pilot flew the T-28 and the passenger flew the pilot's Cessna 150, intending to drop off the Cessna in Fallbrook. The plan was to then depart Fallbrook together in the T-28, stop for lunch in Temecula, and return to Chino.
The T-28 landed in Fallbrook about four minutes ahead of the Cessna. After the Cessna was dropped off, the pilot performed a preflight inspection. The pilot occupied the front seat and the passenger the rear seat. During the takeoff from Fallbrook, when the airplane reached approximately 200 feet above ground level, the engine experienced a total loss of power. The pilot checked the mixture, power, and fuel, and lowered the nose to avoid a stall. The airplane impacted a plant nursery. The pilot estimated that about 30 seconds elapsed from the engine failure to impact. He reported that he forgot to open the canopy before impact, and several people assisted him in exiting the airplane after the crash by prying open the canopy.
The pilot also stated that he performs his own maintenance and recalled last performing maintenance on the airplane about six months before the accident.
Review of automatic dependent surveillance-broadcast (ADS-B) data, video recordings, and audio recordings revealed that the T-28 landed at Fallbrook around 1255. At 1326:01, the airplane taxied to runway 18 and began its takeoff roll at 1331:20. The airplane reached midfield about 12 seconds later at a ground speed of 88 knots. At 1331:44, it was about 300 feet south of the runway identifier markings at an airspeed of 97 knots. The last recorded position was at 1331:49, about 160 feet north of the first identified impact point, at an airspeed of 94 knots on a heading of approximately 180°.
A sound spectrum analysis of a witness's cell phone video indicated the engine was idling smoothly at about 1,530 rpm, then ran roughly for about 10 seconds as it increased to about 2,420 rpm while the airplane moved along the runway. The engine then ran smoothly for 12 seconds as it passed the camera, followed by a sudden decrease in rpm similar to idle, and the airplane impacted seconds later.
Aircraft Information
The North American T-28B is a two-place, single-engine, low-wing monoplane powered by a nine-cylinder Wright R-1820-86 engine rated at 1,425 horsepower, driving a Hamilton Standard three-blade constant-speed propeller. Dual flight controls were installed in the tandem cockpit, and a speed brake was located on the bottom fuselage aft of the main landing gear wheel wells. The tricycle landing gear was fully retractable.
The pilot had owned the airplane for over 10 years and reported no prior carburetor work or issues. He estimated the engine had just under 400 hours since major overhaul at the time of the accident. Maintenance records were incomplete, but the last conditional inspection was recorded on September 5, 2021, at an airframe total time of 14,772.3 hours and a Hobbs time of 362.3 hours. The rebuilt electric fuel pump was purchased in September 2015. The carburetor was last overhauled in February 2010, over 12 years before the accident. The engine-driven fuel pump was last overhauled in February 2010, with removal reason noted as "engine failure" and normal wear. The last engine overhaul was completed in April 2010.
The fuel system comprised four bladder-type fuel cells, an aluminum alloy sump tank with an electric boost pump, a fuel shutoff valve, a fuel strainer, an engine-driven fuel pump, check valves, and necessary feed and vent lines. Fuel flowed by gravity from all cells into the sump tank located in the inboard right wing. A fuel shutoff control handle in each cockpit had ON and OFF positions, simultaneously operating the shutoff valve and electric boost pump. An electric fuel-boost-pump test switch on the electrical panel in the forward right cockpit was wired in series with the pump switch. When held in TEST, power to the electric pump was interrupted to verify engine-driven pump pressure. The electric pump supplied fuel at 19 to 24 psi through the shutoff valve, strainer, and engine-driven pump, which then maintained 23 to 25 psi to the carburetor. If the electric pump failed below 10,000 feet pressure altitude, the engine-driven pump could draw fuel through the electric pump bypass to sustain normal fuel flow. If the engine-driven pump failed, the electric pump could maintain engine operation. The takeoff checklist specified at 1,800 rpm to place the fuel boost pump switch to TEST and check fuel pressure of 21 to 25 psi.
Wreckage and Impact Information
The accident site was located at a nursery about 1,815 feet from the departure end of runway 36. The debris field lay on upsloping terrain with numerous plants in plastic crates and an asphalt pile near the end. The main wreckage, consisting of the engine and most of the fuselage, came to rest upright, and the right wing had impacted a greenhouse structure. Debris was distributed over a 415-foot distance on a median magnetic bearing of about 175°.
On-scene examination showed no external evidence of catastrophic failure. Spark plugs were removed; no mechanical damage was noted, and electrodes and posts exhibited light ash gray coloration consistent with normal operation (the No. 6 plug was oil-soaked). Rotation of the propeller produced "thumb" compression in proper order on all nine cylinders. The valvetrain operated normally with no pre-mishap mechanical malfunction. Both magnetos were found securely clamped and timed within manufacturer specifications. Oil screens were free of debris. The carburetor sustained impact damage, and continuity of the mixture and throttle could not be established.
Over 50 gallons of fuel were found in each inboard wing tank. The fuel selector was in the ON position. Fluid consistent with fuel was found in the carburetor fuel strainer reservoir; the screen was clean and no water was detected. The header tank contained trace amounts of fuel. The electric fuel boost pump was intact, but investigators found a short in the electronic connector box. Disassembly revealed metal shavings lodged in the armature, causing a short. The impeller blades showed wear consistent with shaft instability during rotation. The upper commutator was cracked and worn. Brushes appeared normal. The pump-end bearing was worn on the outside with the labyrinth seal, washer, and shims deformed; the bearing cage was absent. Further examination identified the metal pieces in the armature as fragments of the bearing cage, shaped with rounded lips.
Continuity was established from the boost pump test switch to the pump. Wire continuity from the boost pump to the 20-amp circuit breaker was confirmed. The breaker could be moved in and out but could not be tripped. Subsequent testing showed the breaker operated as expected, but it could not be determined why it failed to trip when installed.
Carburetor examination revealed it was a Stromberg PD-12-K18 injection carburetor (serial number 792490), a double-barrel, downdraft unit with a fuel head enrichment valve, constant head idle spring, automatic mixture control, mechanically operated accelerator pump, and electric primer. Mixture control settings included IDLE CUTOFF, NORMAL, and RICH. The power enrichment valve was operated by a diaphragm exposed to un-metered and metered fuel pressure. Impact damage prevented establishing mixture and throttle continuity. Fuel was present in the carburetor at the site, and corrosion was found in the screen housing and on the spring.
Flow testing of the carburetor showed numerous parameters out of limits. At low power settings, the carburetor ran rich; at high power settings, it ran lean—consistent with insufficient fuel at takeoff power. Disassembly revealed the enrichment valve diaphragm was stiff and rigid, consistent with not being submerged in fuel for long periods. The carburetor manufacturer recommended overhaul every ten years and regular pressurization (monthly in hot, dry climates), noting that internal diaphragms can become brittle if not wetted with fuel regularly.
Tests and Research
Data from the Advanced AF-5500 recorder indicated it began recording at 1331:26. Airspeed was increasing, and the heading matched the accident runway. Manifold pressure and fuel flow increased, then stabilized at 1331:31. Pitch and vertical speed increased shortly after. At 1331:39, manifold pressure and fuel flow began decreasing, followed by a decrease in vertical speed. Airspeed plateaued and then slightly decreased. Pitch decreased but was below 0 degrees for only one sample. The recording ended at 13:31:46.