# NTSB LAX93FA042: Cessna TU-206F, N51198, Clearlake, CA, November 16, 1992 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: November 15, 1992, 16:51 local (Nov 16, 1992, 00:51 UTC) - Place: Clearlake, CA - Coordinates: 38.959453, -122.639808 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.9595&lon=-122.6398&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 2 fatal, 1 serious - Status: Completed, report September 28, 1993 - Report: Approved by Office Director - NTSB case key (mKey): 27810 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX93FA042 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27810/pdf - Page: https://openairdocs.org/ntsb/LAX93FA042 ## Probable cause THE EXHAUST VALVE FAILING DUE TO A COMPLETE FRACTURE WHICH RESULTED IN THE TOTAL LOSE OF ENGINE POWER. FACTORS IN THIS ACCIDENT WERE: 1) THE TERRAIN NOT BEING SUITABLE FOR A FORCED LANDING, AND 2) LOW AMBIENT LIGHT WHICH HAMPERED THE PILOT'S ABILITY TO SEE THE TERRAIN. ## 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, cruise - normal - engine assembly,valve,exhaust - fractured (cause) - engine assembly,valve,exhaust - failure,total (cause) - Forced landing, descent - emergency - In flight collision with terrain/water, descent - emergency - light condition - dusk (contributing factor) - terrain condition - none suitable (contributing factor) - terrain condition - mountainous/hilly (contributing factor) ## Analysis THE PILOT AND HIS TWO PASSENGERS WERE IN CRUISE FLIGHT ON A VFR CROSS COUNTRY WHEN THE AIRPLANE'S ENGINE SUDDENLY BEGAN TO RUN ROUGH. THE PILOT, WHO WAS BEING FLIGHT FOLLOWED BY AN FAA CENTER, DECLARED AN EMERGENCY AND REQUESTED VECTORS TO A NEARBY AIRPORT. WITHIN ABOUT 2 MINUTES THE PILOT REPORTED THAT THE ENGINE COMPLETELY QUIT. THE PILOT ENTERED A POWER OFF FORCED LANDING AND COLLIDED WITH HILLY TERRAIN. NO SUITABLE TERRAIN WAS AVAILABLE FOR THE FORCED LANDING AND THE LIGHTING CONDITIONS WERE REPORTED AS 'DUSK TO DARK.' THE PILOT AND ONE OF HIS PASSENGERS RECEIVED FATAL INJURIES. AN OFF SITE EXAMINATION AND TEARDOWN OF THE ENGINE REVEALED THAT THE NUMBER 5 CYLINDER EXHAUST VALVE STEM BROKE JUST ABOVE THE VALVE HEAD. THE VALVE HEAD FELL INTO THE CYLINDER AND THE ACTION OF THE PISTON CAUSED A HOLE TO BE BROKEN THROUGH THE PISTON CENTER CROWN STRUCTURE. THE VALVE HEAD WAS FOUND WEDGED BETWEEN THE CRANKCASE STRUCTURE AND THE CRANKSHAFT, PREVENTING CRANKSHAFT ROTATION. ## Aircraft - Registration: [N51198](https://openairdocs.org/deregistered/N51198-1994-02-04), registration cancelled 1994-02-04, S/N U20601977 (OpenAirDocs) - Reported make and model: CESSNA TU-206F - Registry model: [Cessna TU206F](https://openairdocs.org/model/cessna-tu206f) (registry code 2073353) (OpenAirDocs) - Category: Airplane - Serial number: U20601977 - Airframe hours: 5746 - Engines: CONTINENTAL TSIO-520-C 285 horsepower reciprocating - Damage: Destroyed - Flight: Personal, Part 91 - Operator: Falcon Aerial - Registered owner: Falcon Aerial - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 16, 1992, 60 hours before - Departed: STS, SANTA ROSA, CA - Destination: CIC, CHICO, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 48; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 1,920 total ## Weather - Conditions: Visual (VMC), Dusk - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none ## 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 19921115046569A](https://openairdocs.org/incident/19921115046569A), Nov 15, 1992: Cessna TU206F, Clear Lake, CA, Destroyed, 2 fatal. Engine swallowed a valve and quit. Crashed on vectors to nearby airport. Pieces of valve jammed crankshaft. ## Other investigations on N51198 (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 OAK73DVM28](https://openairdocs.org/ntsb/OAK73DVM28), Apr 17, 1973: Cessna U206 (N51198), S.Francisco, 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.