History of Flight
On September 10, 2008, at approximately 1350 Pacific daylight time, a Cessna T210N, registration N6278C, ditched in the San Francisco Bay about one-quarter mile north of the Oakland Bay Bridge, Oakland, California. The flight was operated by Ja-Mar Industries, Inc., DBA Air Flight Services, under 14 CFR Part 91. The commercial pilot and one passenger were not injured. The airplane sustained substantial damage to the tail and lower cowling area from impact forces. The local photo flight had departed Reid-Hillview Airport of Santa Clara County (RHV) at about 1320. Visual meteorological conditions prevailed, and no flight plan was filed.
The pilot reported that approximately 30 minutes after departure, the engine began to lose power. He observed zero oil pressure. At the time of the power loss, the airplane was at about 1,500 feet mean sea level. The pilot decided the best landing option was on the water.
Aircraft Information
The airplane was a Cessna T210N, serial number 21063853. Review of the logbooks showed a total airframe time of 8,147 hours at the last annual inspection, dated June 1, 2008. The tachometer read 8010.7 at that inspection and 8147.8 at the accident scene.
The engine was a Teledyne Continental Motors TSIO-520-R, serial number 293904-R, installed in September 1997. Total time since major overhaul was 2,866.8 hours, exceeding the manufacturer's recommended 1,600 hours or 12 years between overhauls. During the annual inspection on June 1, 2008, the number two and three cylinders were replaced with serviceable items; total time since installation was 137.1 hours.
Examination Findings
Investigators examined the wreckage at Plain Parts, Sacramento, California, on September 17, 2008. The engine assembly had a heavy coating of dark gray sealant on the backbone area and forward hardware. Fretting was found on the crankcase halves at the backbone area near the number five and six bolt attachments. Cylinder bays number three, five, and six were intact and undamaged; bays number one, two, and four had mechanical damage, with the number one bay exhibiting displaced material and a small hole.
All main bearing support mating surfaces showed rough surfaces and pitting from fretting. The number one main bearing support diameter had displaced material; the number two support had an elongated lock-slot and displaced material with damage from bearing rotation and extrusion. The number two main bearings were missing from their support diameters, with fragments found in the oil sump and on the support diameter. Larger bearing fragments had smearing of the surface babbit, exposing the copper layer. Number one and three main bearings showed deformation, hard particle passage, and smearing; number four had gouges from hard particle passage; number five had normal wear. No signs of lubrication distress were observed on any main bearings.
The crankshaft had separated into two sections between the number two connecting rod journal and the main bearing journal. The fracture surfaces of the crankshaft cheek had displaced material and thermal discoloration.
Additional Information
A Federal Aviation Administration inspector reviewing the maintenance logbooks noted several discrepancies and non-compliance with manufacturers' recommendations throughout several inspections.