# NTSB ANC14LA040: Cessna U206C, N29137, Chitina, AK, June 9, 2014 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 9, 2014, 13:05 local (21:05 UTC) - Place: Chitina, AK - Coordinates: 61.515556, -144.440277 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.5156&lon=-144.4403&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: No injuries - Injuries: 2 uninjured - Status: Completed, report May 1, 2017 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Continental Motors, Copper Valley Air Service, Federal Aviation Administration - NTSB case key (mKey): 89427 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC14LA040 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89427/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89427 - Page: https://openairdocs.org/ntsb/ANC14LA040 ## Probable cause The failure of the engine’s No. 1 piston connecting rod retaining bolts due to fatigue, which resulted in a total loss of engine power during cruise flight. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant](https://openairdocs.org/ntsb-findings/01057100): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Cessna U206C, 2 cases](https://openairdocs.org/ntsb-findings/01057100/cases.md?model=2073332), [All aircraft, 198 cases](https://openairdocs.org/ntsb-findings/01057100/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 U206C, 3 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2073332), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Cessna U206C, 3 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2073332), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna U206C, 4 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2073332), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Landing: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Cessna U206C, 3 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2073332), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis While in level cruise on the scheduled passenger flight, the airline transport pilot heard a loud "bang," followed by a quieter "bang" and a total loss of engine power. He conducted a forced landing to a densely-wooded area, during which the airplane nosed over, resulting in substantial damage to the wings and horizontal stabilizer. A visual examination of the engine revealed a crack in the crankcase. A subsequent examination of the No. 1 piston assembly revealed fatigue fractures in both connecting rod retaining bolts. Additional internal damage to the engine was found to be consistent with damage caused by the release of the connecting rod from the crankcase. ## Factual narrative On June 9, 2014, about 1305 Alaska daylight time, a Cessna U206C airplane, N29137, sustained substantial damage during a forced landing, following a loss of engine power near Chitina, Alaska. The airplane was operated by Copper Valley Air Service, Glennallen, Alaska, as a visual flight rules (VFR) scheduled commuter flight under the provisions of 14 Code of Federal Regulations (CFR) Part 135.The certificated airline transport pilot and sole passenger were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight departed Gulkana Airport, Glennallen, Alaska, at 1235 destined for McCarthy, Alaska. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 10, the pilot stated that he was in level cruise flight when he heard a loud "bang", followed by a quieter "bang", prior to a total loss of engine power. He made a forced landing to an area of densely populated black spruce trees. During the forced landing the airplane nosed over, sustaining substantial damage to wings and horizontal stabilizer. The engine was removed from the airframe and sent to the facilities of Continental Motors, Inc. (CMI) Mobile, Alabama, for further examination. The engine was examined on February 24, 2015, by representatives from CMI under the supervision of the NTSB IIC, along with another NTSB investigator. A visual inspection revealed that the right crankcase half was cracked, beginning at the number one cylinder mount continuing upward and slightly forward about 3 inches. The examination revealed that most of the engine's major internal damage was associated with the number one piston assembly. The number one piston was fractured at the piston bore, releasing the number one rod and piston pin assembly. The unsupported number one rod and piston pin assembly caused damage to the rear section of the crankcase and camshaft. The number one rod had released from the crankshaft, and exhibited extreme mechanical damage. There were no signs of lubrication distress. A CMI metallurgist, with permission from the NTSB IIC, examined the number one connecting rod retaining bolts. The metallurgical examination revealed beach marks on the fractured surfaces of both connecting rod bolts consistent with fatigue fractures that initiated at the surface. The closest weather reporting facility was Gulkana Airport, about 58 miles northwest of the accident site. At 1253, a weather observation from Gulkana Airport was reporting, in part: wind from 160 degrees, at 9 knots; visibility, 10 statute miles; clouds and sky condition, 7,000 feet overcast, temperature, 57 degrees F; dew point 41 degrees F; altimeter, 29.91 inHG. ## Aircraft - Registration: [N29137](https://openairdocs.org/deregistered/N29137-2015-04-01), registration cancelled 2015-04-01, S/N U206-1107, built 1968 (OpenAirDocs) - Reported make and model: CESSNA U206C - Registry model: [Cessna U206C](https://openairdocs.org/model/cessna-u206c) (registry code 2073332) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: U206-1107 - Year built: 1968 - Airframe hours: 65537 - Engines: Continental Motors IO-520 300 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Copper Valley Air Service - Registered owner: Copper Valley Air Service - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 27, 2014 - Departed: GKN, GULKANA, AK - Destination: 15Z, MCCARTHY, AK - Flight plan: Company VFR - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; injuries: none; airline transport; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review May 31, 2013; seat: left; flight hours: 27,850 total, 1,800 in this make and model, 16,000 as pilot in command, 160 in the last 90 days, 50 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 7,000 ft overcast - Temperature: 57 °F, dew point 41 °F - Observed at: PAGK, 58 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 20140609009179A](https://openairdocs.org/incident/20140609009179A), Jun 9, 2014: Cessna U206C, Mc Carthy, AK, Substantial damage. Pilot started climb due to rising terrain. Climbed from 3200 feet to 4000 feet. During the climb the pilot heard a loud clank and a bang. At this point the… ## Docket (3 files) The files NTSB released with the investigation on March 30, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89427. 2.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 566 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40450549&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - CMI Metallurgical Report (item 2, .PDF, 4 photos, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40450550&FileExtension=.PDF&FileName=CMI%20Metallurgical%20Report-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 3, .PDF, 289 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40450551&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.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.