# NTSB ANC10LA056: Cessna U206G, N4596U, Iliamna, AK, June 30, 2010 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: June 29, 2010, 17:45 local (Jun 30, 2010, 01:45 UTC) - Place: Iliamna, AK - Coordinates: 59.648334, -155.419998 - Nearby events: https://openairdocs.org/map.md?lat=59.6483&lon=-155.4200&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor, 5 uninjured - Status: Completed, report January 17, 2012 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA FSDO-03 - NTSB case key (mKey): 76484 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC10LA056 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76484/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76484 - Page: https://openairdocs.org/ntsb/ANC10LA056 ## Probable cause The total loss of engine power during cruise flight due to a fractured crankshaft. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Cessna U206G, 3 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=2073356), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Cessna U206G, 4 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=2073356), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Cessna U206G, 10 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2073356), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna U206G, 5 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2073356), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-flare/touchdown: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna U206G, 16 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2073356), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The float-equipped airplane was in cruise flight on a sightseeing flight when there was a total loss of engine power. After several unsuccessful attempts to restart the engine, the pilot made a forced landing on tundra-covered terrain, and the airplane nosed over. Postaccident disassembly of the engine found that the crankshaft had fractured at the No. 2 journal. Laboratory examination of the crankshaft found "ladder cracking" associated with the journal fracture, which is consistent with a reduced oil flow and overheating of the surface area. At the time of the accident, the engine had 441 hours of operation since major overhaul, which was performed on October 21, 2008. ## Factual narrative On June 29, 2010, about 1745 Alaska daylight time, a float-equipped Cessna U206G airplane, N4596U, sustained substantial damage to the wings, rudder and fuselage during an emergency off-airport landing, about 16 miles west-southwest of Iliamna, Alaska. The airplane was operated by Rust's Flying Service, Anchorage, Alaska, as a visual flight rules (VFR) revenue sightseeing flight under 14 Code of Federal Regulations, Part 135, when the accident occurred. The commercial pilot and four passengers were not injured; the remaining passenger received minor injuries. The flight was returning to the operator's base at the Lake Hood Seaplane Base, Anchorage. Company flight following procedures were in effect. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), a representative for the operator said the pilot reported a complete loss of engine power that precipitated an emergency descent, and off-airport landing. The pilot reportedly told him he saw a rise in the exhaust gas temperature (EGT) prior to the loss of power. The float-equipped airplane landed on tundra-covered ground and nosed over. The pilot reported adding 42 gallons of aviation fuel prior to the return flight to Anchorage. In a written statement to the FAA dated July 1, the pilot wrote that about 40 minutes into the flight he saw the EGT rise above the normal cruise temperature. He enriched the mixture from 15 gallons per hour (GPH) to 18 GPH, to cool the engine. Shortly thereafter the engine quit completely. After several failed attempts to restart the engine, he focused on landing the airplane. On August 18, the airplane was examined by the NTSB IIC at an airplane maintenance facility in Wasilla, Alaska. During an attempt to rotate the propeller, it was discovered that the propeller would not rotate, and the rear accessory portion of the engine did not appear to be connected through the crankshaft to the propeller. On November 9, the airplane's engine was disassembled at an airplane maintenance facility in Palmer, Alaska. In attendance with the IIC were representatives from the FAA, and the engine manufacturer. During the disassembly it was discovered that the engine's crankshaft had fractured, and separated at the number 2 journal. The crankshaft was shipped to the NTSB material laboratory, Washington, D.C., for examination. The laboratory engineer found "ladder cracking," indicative of oil starvation, associated with the journal fracture. The NTSB material laboratory report is contained in the public docket for this report. Engine History Prior to October 21, 2008 the accident airplane's engine, serial number 286450-R was overhauled by Aero Recip, Anchorage, Alaska. The overhauled engine was sold to Mulchatna Air, Dillingham, Alaska, and installed in one of their airplanes. During the first flight, the engine lost oil pressure, the pilot landed, and the engine oil filter was checked for metal particles. Finding metal in thefilter, the owner requested the engine be replaced by Aero Recip, which it was. During a telephone conversation with the NTSB IIC, the owner of Mulchatna Air said a couple days after returning the engine, he received a telephone call from Aero Recip, stating they could not find anything wrong with the engine, and they were returning it to service. According to the engine's log book, on June 24, 2009, the engine was removed from the airplane due to possible metal contamination. The engine was partially disassembled by Aero Recip, and inspected. No contamination was found, so the engine was reassembled, and test run three times. After each run the oil filter was examined, with no notable contaminates or ferrous metal found. Aero Recip returned the engine to service. On July 7, 2009 the engine was installed in the accident airplane. At the time of the accident, the engine had 441 hours of operation since the October 21, 2008 major overhaul. ## Aircraft - Registration: [N4596U](https://openairdocs.org/aircraft/N4596U), registered now, S/N U20604990, built 1979 (OpenAirDocs) - Reported make and model: CESSNA U206G - Registry model: [Cessna U206G](https://openairdocs.org/model/cessna-u206g) (registry code 2073356) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: U20604990 - Airframe hours: 15612 - Engines: CONT MOTOR IO 520 SERIES 300 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Rusts Flying Service Inc, doing business as Rusts Flying Service - Registered owner: Rustair Inc - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, June 3, 2010 - Departed: AKN, King Salmon, AK - Destination: PALH, Anchorage, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land, multi-engine sea, single-engine sea; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review May 24, 2010; seat: left; flight hours: 19,900 total, 3,000 in this make and model, 80 in the last 90 days, 80 in the last 30 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 100° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: 3,300 ft overcast - Temperature: 54 °F, dew point 45 °F - Altimeter: 29.79 inHg - Observed at: ILI, 16 nm away ## 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 20100629038099A](https://openairdocs.org/incident/20100629038099A), Jun 29, 2010: Cessna U206G, Iliamna, AK, Substantial damage. Pilot fueled aircraft with 42 gallons of fuel, 20-L and 22-R tank. Pilot flew aircraft for about 20 min. On each tank. In cruise the pilot made a richer… ## Other investigations on N4596U (2) 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 GAA16CA272](https://openairdocs.org/ntsb/GAA16CA272), May 23, 2016: Cessna U206G (N4596U), Chinita Bay, AK, substantial damage. Probable cause: The pilot's selection of unsuitable terrain for taxi, resulting in a tail strike and aft fuselage substantial damage. - [NTSB ANC95LA126](https://openairdocs.org/ntsb/ANC95LA126), Aug 2, 1995: Cessna 206G (N4596U), Skwentna, AK, substantial damage. Probable cause: THE PILOT'S IMPROPER HANDLING OF THE AIRCRAFT (PROLONGED YAWING MANEUVER DURING STEP TAXI TURN), WHICH RESULTED IN UNCOVERING OF THE FUEL TANK OUTLETS AND SUBSEQUENT FUEL STARVATION DURING TAKEOFF. ## Docket (5 files) The files NTSB released with the investigation on December 1, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76484. 3.6 MB in all. - Materials Laboratory 15 - Factual Report 11-105 with 7 embedded photos (item 1, .PDF, 7 photos, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356947&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2011-105%20with%207%20embedded%20photos-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 679 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358837&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conference - Pilot (item 3, .PDF, 121 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358838&FileExtension=.PDF&FileName=Record%20of%20Conference%20-%20Pilot-Redacted.PDF - Record of Conversation - Mulchatna Air (item 4, .PDF, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358839&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Mulchatna%20Air-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 5, .PDF, 152 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40358840&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF 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.