# NTSB ANC92LA152: Cessna 206, N8070Z, Fort Yukon, AK, September 2, 1992 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 1, 1992, 17:42 local (Sep 2, 1992, 01:42 UTC) - Place: Fort Yukon, AK - Coordinates: 66.560287, -145.24916 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=66.5603&lon=-145.2492&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor, 1 uninjured - Status: Completed, report December 16, 1993 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 5796 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC92LA152 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5796/pdf - Page: https://openairdocs.org/ntsb/ANC92LA152 ## Probable cause FATIGUE FAILURE OF AN ENGINE CYLINDER PRECIPITATED BY THE PILOT-IN-COMMAND INTENTIONALLY EXCEEDING THE ENGINE PERFORMANCE RATINGS IN ORDER TO SUSTAIN FLIGHT IN THE GROSSLY OVERWEIGHT CONDITION. A FACTOR CONTRIBUTING TO THE ACCIDENT WAS THE HIGH GRASS. A FACTOR CONTRIBUTING TO THE SEVERITY OF THE PASSENGER'S INJURY WAS THE UNSECURED CARGO. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, cruise - normal - aircraft weight and balance - exceeded, pilot in command (cause) - engine assembly,cylinder - overtemperature (cause) - powerplant controls - improper use of, pilot in command (cause) - engine assembly,cylinder - fatigue (cause) - Forced landing, landing - flare/touchdown - Nose over, landing - roll - terrain condition - high vegetation (contributing factor) - tie down - not performed, pilot in command (contributing factor) ## Analysis THE PILOT LOADED THE 2 PASSENGERS AND GEAR IN THE AIRPLANE TO THE EXTENT THAT IT TOOK SUCCESSIVE ATTEMPTS TO CLOSE THE DOOR DUE TO THE GEAR WHICH 'FILLED UP THE AIRPLANE TO THE ROOF.' THE REAR PAX HAD TO LAY ON TOP OF MEAT AND CAMP SUPPLIES WITH 2 DOGS IN HIS LAP. THE AIRPLANE WAS ESTIMATED TO BE 772 LBS OVER MAX GROSS WEIGHT AT TAKEOFF. AFTER TAKEOFF THE AIRPLANE CLIMBED SLOWLY FOR APRX 55 MIN AT TAKEOFF POWER. A 'SLEDGEHAMMER' SOUND PRECEDED THE APPEARANCE OF OIL FLOWING INTO THE CABIN AREA. NO REDUCTION OF POWER WAS OBSERVED. THE OIL PRESSURE BEGAN DROPPING RAPIDLY, AND THE PILOT MADE A PRECAUTIONARY LANDING ON A BEACH. THE AIRPLANE NOSED OVER IN GRASS. ENGINE TEARDOWN EXAMINATION REVEALED THAT THE #6 CYLINDER HAD FAILED THROUGH THE HEAD-TO-BARREL THREADED JOINT. METALLURGICAL EXAMINATION REVEALED THAT THE FAILURE WAS THE RESULT OF FATIGUE CRACKING IN THE CYLINDER HEAD CASTING. THIS TYPE OF FAILURE OCCURS WHEN THE CYLINDER IS OPERATED AT ELEVATED TEMPERATURES (ABOVE MAXIMUM ALLOWABLE) FOR A CONSIDERABLE PERIOD OF TIME. ## Aircraft - Registration: [N8070Z](https://openairdocs.org/aircraft/N8070Z), registered now, S/N U206-0470, built 1965 (OpenAirDocs) - Reported make and model: CESSNA 206 - Registry model: [Cessna U206A](https://openairdocs.org/model/cessna-u206a) (registry code 2073316) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: U206-0470 - Engines: CONTINENTAL IO-520A 285 horsepower reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Operator: Larry R. Rivers - Registered owner: Larry R. Rivers - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 2, 2000, 35 hours before - Departed: RED SHEEP CREEK, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; private; airplane ratings: single-engine sea, single-engine land; medical: class 2, valid medical--no waivers/lim.; flight hours: 4,900 total, 720 in this make and model, 4,830 as pilot in command, 155 in the last 90 days, 148 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 50 statute miles - Lowest ceiling: 7,000 ft overcast - Temperature: 50 °F, dew point -0 °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 19920901035009A](https://openairdocs.org/incident/19920901035009A), Sep 1, 1992: Cessna U206A, Fort Yukon, AK, Substantial damage. Over gross on takeoff 772 lbs. Got off on second attempt. Lost oil pressure. Nosed over landing.NR6 cylinder failed ## Other investigations on N8070Z (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 ANC18TA070](https://openairdocs.org/ntsb/ANC18TA070), Sep 9, 2018: Cessna U206 (N8070Z), Willow, AK, substantial damage. Probable cause: The pilot receiving instruction's failure to maintain control during a night landing pattern crosswind turn due to spatial disorientation and the flight instructor's inadequate supervision and… 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.