# NTSB ANC08LA097: Piper PA-31-350, N40YR, Aniak, AK, August 4, 2008 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 4, 2008, 15:50 local (23:50 UTC) - Place: Aniak, AK - Coordinates: 61.581665, -159.54306 - Nearby events: https://openairdocs.org/map.md?lat=61.5817&lon=-159.5431&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: Serious injuries - Injuries: 1 serious, 2 minor, 5 uninjured - Status: Completed, report April 15, 2009 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA-AL-ANC FSDO 03, Frontier Flying Service Inc. - NTSB case key (mKey): 68681 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC08LA097 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/68681/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=68681 - Page: https://openairdocs.org/ntsb/ANC08LA097 ## Probable cause A partial loss of engine power during takeoff due to a failure of the left engine's turbocharger as a result of the failure of a turbine shaft bearing. Contributing to the accident was unsuitable terrain for a forced landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Turbocharging (recip only): turbocharger](https://openairdocs.org/ntsb-findings/01058120): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Piper PA-31-350, 1 case](https://openairdocs.org/ntsb-findings/01058120/cases.md?model=7103110), [All aircraft, 29 cases](https://openairdocs.org/ntsb-findings/01058120/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome (probable cause); cases with it: [Piper PA-31-350, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=7103110), [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. - [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Piper PA-31-350, 3 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=7103110), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Piper PA-31-350, 9 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7103110), [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: [Piper PA-31-350, 4 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=7103110), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The airline-transport-certificated pilot was departing in a twin-engine airplane that was about 130 pounds below its maximum gross weight. About 200 feet above the ground, the pilot reported a loss of engine power in the left engine and smoke was seen coming from the left engine by ground witnesses. The pilot indicated that he feathered the left engine, but that the airplane was descending and he elected to make an emergency landing on a gravel bar about .5 mile from the airport. Following the accident, the operator's maintenance personnel removed the left engine from the airframe and shipped it to an engine repair facility for examination. The airplane's left engine, which was equipped with a turbocharger, was placed on a test stand where it was started and ran, but it would not produce power (measured in manifold pressure) above ambient pressure. The engine's turbocharger was removed and replaced. A second engine run, with the new turbocharger installed, resulted in the engine developing full power. The original turbocharger was disassembled and inspected. The inspection revealed that one of the turbine shaft bearings had failed and that the turbine shaft and blades were damaged. One thrust bearing had fractured, with half of the bearing missing. ## Factual narrative On August 4, 2008, about 1550 Alaska daylight time, a twin engine Piper PA-31 airplane, N40YR, sustained substantial damage following a loss of engine power during takeoff/initial climb, about 1/2 mile north of Aniak, Alaska. The airplane was being operated as a visual flight rules (VFR) scheduled domestic commuter flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated as Flight 8606, by Frontier Flying Service Inc., Fairbanks, Alaska. The airline transport certificated pilot was not injured. One passenger received serious injuries, 2 passengers received minor injuries, and 4 passengers were not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight was en route to Shageluk, Alaska. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on August 4, the director of operations for the operator reported that the airplane had just departed runway 28 at Aniak. The airplane was about 130 pounds below its maximum gross weight. About 200 feet above the ground, the pilot reported a loss of engine power in the left engine, and smoke was seen coming from the left engine by ground witnesses. The pilot indicated that he feathered the left engine, but the airplane was descending, and he elected to make an emergency landing on a gravel bar with the landing gear extended. During the touchdown, the nose landing gear collapsed. The airplane received structural damage to the fuselage and wings. Following the accident, the operator's maintenance personnel removed the left engine from the airframe and shipped it to an engine repair facility in Anchorage, Alaska. On August 15, 2008, the airplane's left engine, which was equipped with a turbocharger, was examined at the engine repair facility. The examination was overseen by an NTSB air safety investigator, and attended by representatives from the operator and the FAA. The engine was placed on a test stand where it was started and ran, but it would not produce power (measured in manifold pressure) above ambient pressure. The engine's turbocharger was removed and replaced. A second engine run, with the new turbocharger installed, resulted in the engine developing full power. The original turbocharger was disassembled and inspected. The inspection revealed that one of the turbine shaft bearings had failed, and the turbine shaft and blades were damaged. One thrust bearing had fractured and one half of the bearing was missing. ## Aircraft - Registration: [N40YR](https://openairdocs.org/deregistered/N40YR-2009-01-14), registration cancelled 2009-01-14, S/N 31-7952008, built 1979 (OpenAirDocs) - Reported make and model: PIPER PA-31-350 - Registry model: [Piper PA-31-350](https://openairdocs.org/model/piper-pa-31-350) (registry code 7103110) (OpenAirDocs) - Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 31-7952008 - Airframe hours: 10047 - Engines: Lycoming TIO-54D 350 horsepower reciprocating; Lycoming LTIO-54D 350 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Frontier Flying Service Inc., doing business as Frontier Alaska - Registered owner: Frontier Flying Service Inc. - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, July 25, 2008, 14 hours before - Departed: PANI, Aniak, AK - Destination: PAHX, Shageluk, AK - Flight plan: Company VFR - Airport: PANI, Aniak, runway 28, 6,000 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; injuries: none; commercial, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review July 10, 2008; seat: left; flight hours: 3,941 total, 98 in this make and model, 2,846 as pilot in command, 293 in the last 90 days, 92 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: 3,000 ft overcast - Temperature: 55 °F, dew point 45 °F - Altimeter: 30.11 inHg - Observed at: PANI, 1 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 20080804848069A](https://openairdocs.org/incident/20080804848069A), Aug 4, 2008: Piper PA31350, Aniak, AK, Substantial damage. (-23) On August 4, 2008, about 1550 Alaska daylight time a Piper PA-31-350 airplane, N40YR, had a controlled crashed, about a mile straight out of runway 28,… ## Docket (3 files) The files NTSB released with the investigation on February 13, 2009, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=68681. 851 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 550 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40308116&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Pilot Statement (item 2, .PDF, 230 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40308117&FileExtension=.PDF&FileName=Pilot%20Statement-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 3, .PDF, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40308118&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.