# NTSB LAX98LA262: Cessna 150M, N704UV, Santa Paula, CA, August 10, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 10, 1998, 08:30 local (15:30 UTC) - Place: Santa Paula, CA - Coordinates: 34.399749, -119.070892 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.3997&lon=-119.0709&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report June 22, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 43687 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX98LA262 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43687/pdf - Page: https://openairdocs.org/ntsb/LAX98LA262 ## Probable cause Failure of the number one cylinder due to a fatigue crack that had originated from corrosion pits at the cooling fin. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, maneuvering - engine assembly,cylinder - corroded (cause) - engine assembly,cylinder - fatigue (cause) - engine assembly,cylinder - cracked (cause) - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, landing - roll - terrain condition - rock(s)/boulder(s) - Nose over, landing - roll ## Analysis The student pilot was on a local solo flight. After practicing various maneuvers the engine began to run rough, vibrate, and smoke. The pilot made a forced landing into a riverbed and came to rest inverted. The number one cylinder was found to have a circumferential crack extending approximately 325 degrees around the barrel between the 8th and 9th cooling fins. The cylinder was further examined by a metallurgist, who reported that the barrel fins were covered with an iron oxide. The examination further revealed a fatigue crack that emanated from corrosion pits at the root radius between the 8th and 9th cooling fins. The remaining portion of the fracture exhibited an overstress separation. ## Factual narrative On August 10, 1998, at 0830 hours Pacific daylight time, a Cessna 150M, N704UV, made a forced landing in a riverbed due to a rough running engine, struck a boulder, and nosed over near Santa Paula, California. The airplane, operated by C.P. Aviation of Santa Paula as an instructional flight under 14 CFR Part 91, sustained substantial damage. The student pilot, the sole occupant, was not injured. Visual meteorological conditions existed for the local instructional flight and no flight plan was filed. The flight had originated from the Santa Paula airport at 0800 on the day of the accident. In an interview, the pilot stated that he was practicing a series of climbs, descents, and ground reference maneuvers, when the airplane began experiencing a rough running, vibrating engine that was producing smoke. The airplane was examined by a Safety Board investigator and it was noted that the number one cylinder had a circumferential crack approximately mid-barrel, and the corresponding top spark plug was oil fouled. According to the Champion Spark Plugs Check-A-Plug chart AV-27, the remaining spark plugs exhibited coloration consistent with normal operation. The oil screen was removed and visually inspected. It contained residual oil and metallic flakes. Examination of the number one cylinder by a metallurgist from the Safety Board, disclosed that the fins of the barrel were covered with iron oxide. Closer examination revealed a fatigue crack, which emanated from corrosion pits at the root radius between the 8th and 9th cooling fins. The corrosion pits measured approximately 0.002 inch in depth, and the fatigue crack propagated 325 degrees circumferentially round the cylinder. The metallurgist reported that the remaining portion of the fracture exhibited features typical of overstress separation. Examination of the airplane records revealed that the total time on the engine and the No.'s 1, 2, and 3 cylinders was approximately 1912.4 hours, 112 hours over the engine manufacturer's recommended time between overhaul (TBO). The number 4 cylinder had been replaced on December 20, 1996, due to a crack around the barrel between the cylinder head and base of the cylinder. The crack encompassed approximately 50 percent of the circumference of the cylinder barrel. ## Aircraft - Registration: [N704UV](https://openairdocs.org/deregistered/N704UV-2012-05-30), registration cancelled 2012-05-30, S/N 15078893 (OpenAirDocs) - Reported make and model: Cessna 150M - Registry model: [Cessna 150M](https://openairdocs.org/model/cessna-150m) (registry code 2071830) (OpenAirDocs) - Category: Airplane - Serial number: 15078893 - Airframe hours: 6354 - Engines: Continental O-200-A 100 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: C.P. Aviation - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: 100 hour, July 8, 1998, 39 hours before - Departed: SZP ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; student; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 39 total, 27 in this make and model, 5 as pilot in command, 18 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 75 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19980810025129A](https://openairdocs.org/incident/19980810025129A), Aug 10, 1998: Cessna 150M, Santa Paula, CA, Substantial damage. (-23) On August 10, 1998 at 0815 N704UV made a forced landing in a riverbed west of the city of filmore. The student pilot explained that his engine started… ## Other investigations on N704UV (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB SEA85LA119](https://openairdocs.org/ntsb/SEA85LA119), May 18, 1985: Cessna 150M (N704UV), Santa Rosa, CA, substantial damage From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.