Accident Overview
On January 19, about 0800 Pacific standard time, a Piper PA-28R-200 (registration N57355) was substantially damaged during an accident near Carlsbad, California. The flight instructor, pilot receiving instruction, and a passenger were not injured. The aircraft was being operated under Title 14 Code of Federal Regulations Part 91 as an instructional flight.
Flight Events
The flight instructor reported that the flight was planned to Santa Ana, California, for the pilot to accumulate flight time. A preflight inspection was normal, with the oil sump containing about 6 quarts of oil. After an uneventful engine run-up, the aircraft departed and turned right to a northerly heading after climbing to approximately 2,500 ft mean sea level (msl). As the aircraft reached about 3,200 ft msl, the instructor noticed the oil pressure gauge indicated below 0 psi while oil temperature remained in the normal range. The instructor notified ATC and informed them of a deviation to a nearby airport.
While the pilot attempted to maintain 3,000 ft msl, the instructor observed the propeller default to maximum rpm and anticipated imminent engine failure. Minutes later, smoke entered the cockpit through the defrosters, accompanied by a faint oil smell. A loud sound from the engine compartment followed, and the propeller stopped turning, with smoke emanating from the engine cowling.
The pilots decided on a water landing. The pilot flew the aircraft to the surface, and the instructor notified ATC of the engine failure and intended landing site. The aircraft touched down about 50 yards from the shoreline with the landing gear retracted.
Maintenance History
A review of maintenance records revealed that an annual inspection was completed on September 15, 2022, about four months before the accident. The engine had been overhauled in November 2016. At the last annual inspection, the engine had accumulated approximately 1,280 hours since overhaul.
Aircraft Damage
Postaccident examination showed the left wing fractured and separated about midspan. Buckling and bending were observed on the fuselage aft of the wings, and damage to the right wing was noted about midspan.
Engine Examination
The engine remained attached to its mounts but was exposed to salt water during the accident and contained rock debris from impact with terrain. All accessories remained attached with no loose wiring or fluid leakage. The engine case was breached between the push tubes of the No. 2 cylinder, showing a visible puncture along the push-pull tube channel. The oil dipstick indicated a mixture of oil, water, and sand.
The oil sump, attached to the engine case, was severely corroded due to saltwater exposure. A hole about 3 inches wide was observed in the sump below the No. 2 cylinder induction tube connection. The area was white, consistent with saltwater corrosion, soft, and easily penetrated when pressure was applied.
Internal examination after removing the No. 1 cylinder revealed that the No. 2 connecting rod had separated from the crankshaft, with a small portion of the end cap remaining attached to the rod shank. Rotational score marks were present on the camshaft at the No. 2 connecting rod. A heat gradient was observed along the No. 2 connecting rod shank, consistent with thermal stress. The No. 2 connecting rod bearing had separated from the journal, which was mechanically damaged. The remaining section of the end cap displayed score marks consistent with interfacing at the No. 2 crankshaft journal.
Further examination showed that the crankshaft main bearings were intact with normal wear. Crankcase halves showed no signs of fretting or main bearing shift. Oil galley plugs were removed, and the galleys were free of obstruction. The No. 1, 2, and 3 connecting rod bearings had thermal discoloration and metal deformation. Crankshaft oil galleys were clear. The center bearing exhibited evidence of thermal distress and rotational scoring. Pushrods were intact except for the No. 2 cylinder pushrods, which were damaged postaccident by saltwater. Intake and exhaust valves for cylinders 2 and 4 could not be inspected due to saltwater damage. Each rocker arm was securely attached.
The engine was mostly devoid of oil. The oil return line at the No. 3 cylinder contained oil sludge, as did the oil sump, which also showed saltwater corrosion. The accessory housing was unremarkable except for the oil pump, which exhibited heavy resistance when rotated by hand. The pump gears and housing contained oil with non-ferrous fragments, sludge along the gear tracks, and rust on one gear. After cleaning, the pump turned normally. No obstructions were found in the oil galleys.