# NTSB ANC18LA080: Piper PA18, N5907Y, Delta Junction, AK, September 30, 2018 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 30, 2018, 13:30 local (21:30 UTC) - Place: Delta Junction, AK - Coordinates: 64.610557, -144.616943 - Nearby events: https://openairdocs.org/map.md?lat=64.6106&lon=-144.6169&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report June 29, 2020 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 98426 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC18LA080 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/98426/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=98426 - Page: https://openairdocs.org/ntsb/ANC18LA080 ## Probable cause The total loss of engine power due to carburetor icing, which resulted from the pilot's failure to use carburetor heat while operating at low power settings in conditions conducive to the formation of carburetor ice. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause) - [Ice/rain protection system: intake anti-ice, deice](https://openairdocs.org/ntsb-findings/01023020): Aircraft › Aircraft systems · Not used/operated (probable cause) - [Action: delayed action](https://openairdocs.org/ntsb-findings/02041025): Personnel issues › Action/decision · Pilot (probable cause) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause) ## Analysis According to the pilot, while maneuvering the airplane in mountainous terrain, he reduced engine power and initiated a descent; the engine then began to cough and run roughly. He applied full throttle, and the engine subsequently lost total power. In an attempt to restore power, he applied carburetor heat and switched fuel tanks while initiating an emergency descent. The engine restarted; however, it continued to run roughly and would not develop full power. He continued the emergency descent and landed the airplane on a mountain ridge. Upon touchdown, the left main landing gear separated from the fuselage and the left wing struck the ground, which resulted in substantial damage to the left wing. A postaccident examination of the engine, which included an engine test run, revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. According to a carburetor icing probability chart, an airplane operating in the ambient conditions at the accident site could expect carburetor icing while at cruise power and at glide power. It is likely that, when the pilot reduced engine power for the descent, carburetor ice formed and resulted in the loss of engine power. ## Factual narrative On September 30, 2018, about 1330 Alaska daylight time, a tundra tire and tailwheel-equipped Piper PA-18 Super Cub airplane, N5907Y, sustained substantial damage during a forced landing following a partial loss of engine power while maneuvering near Delta Junction, Alaska. The private pilot was not injured. The airplane was registered to and operated by the pilot as a 14 Code of Federal Regulations Part 91 visual flight rules (VFR) flight. Visual meteorological conditions prevailed, and no flight plan had been filed. The local area flight departed Delta Junction Airport (D66), Delta Junction, Alaska about 1130 for the upper Salcha River area with a planned return to D66. According to the pilot, while maneuvering in mountainous terrain, he reduced engine power and initiated a descent when the engine began to cough and run rough. He applied full throttle and the engine subsequently lost all power. In an attempt to restore power, he applied carburetor heat and switched fuel tanks while initiating an emergency descent to a mountain ridge. The pilot stated that the engine appeared to restart; however, it continued to run rough and would not develop full power. He elected to continue with the emergency descent and landing on the mountain ridge. Upon touchdown, the left main landing gear separated from the fuselage and the left wing struck ground resulting in substantial damage to the left wing. On October 12, the engine, while still mounted on the accident airplane's airframe, was operated under the direction of the NTSB IIC. The engine accelerated normally and a series of power adjustments from idle to full power were conducted without any hesitation, stumbling or interruption in power. During the engine test the magnetos were checked and a drop of about 25 rpm was noted for the left and right magnetos. According to the carburetor icing probability chart, an airplane operating in the ambient conditions at the accident site could expect carburetor icing while at cruise power and at glide power. A Lycoming Service Instruction states in part: "Landing Approach – In making a landing approach, the carburetor heat is generally in the 'Full Cold' position. However, if icing conditions are suspected apply 'Full Heat.' In the case that full power needs to be applied under these conditions, as for an aborted landing, return the carburetor heat to 'Full Cold' after full power application." ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event) - [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) ## Aircraft - Registration: [N5907Y](https://openairdocs.org/aircraft/N5907Y), registered now, S/N 18-8414, built 1966 (OpenAirDocs) - Reported make and model: Piper PA18 (150) - Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-8414 - Year built: 1966 - Airframe hours: 4782.8 - Engines: Lycoming O-360 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 8, 2018 - Departed: Delta Junction, AK - Destination: Delta Junction, AK - Equipment: Stall warning system, Satellite tracking device, Handheld GPS, Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review August 24, 2018; seat: front; restraint: 4-point; flight hours: 475 total, 475 in this make and model, 440 as pilot in command, 20 in the last 90 days, 15 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 10 knots - Visibility: 10 statute miles - Temperature: 52 °F, dew point 27 °F - Altimeter: 30.15 inHg - Observed at: D66 ## 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 20180930019339A](https://openairdocs.org/incident/20180930019339A), Sep 30, 2018: Piper PA-18-150, Delta Junction, AK, Substantial damage. On September 30 2018 the pilot was flying his aircrat in mountanous terrain. He reduced power and began a descent when the engine began to run rough. The pilot… ## Other investigations on N5907Y (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ANC86LA148](https://openairdocs.org/ntsb/ANC86LA148), Sep 5, 1986: Piper PA-18 (N5907Y), Farewell, AK, substantial damage - [NTSB ANC82DA098](https://openairdocs.org/ntsb/ANC82DA098), Sep 23, 1982: Piper PA-18 (N5907Y), Near Port Alswo, AK, substantial damage ## Docket (3 files) The files NTSB released with the investigation on March 18, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=98426. 2.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481314&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Carburetor Icing Chart (item 2, .PDF, 49 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481315&FileExtension=.PDF&FileName=Carburetor%20Icing%20Chart-Master.PDF - Photos (item 3, .PDF, 764 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40481316&FileExtension=.PDF&FileName=Photos-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; 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.