# NTSB ANC19LA027: Helio H391, N10CJ, Hope, AK, June 12, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: June 11, 2019, 22:30 local (Jun 12, 2019, 06:30 UTC) - Place: Hope, AK - Coordinates: 60.811943, -150.00666 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.8119&lon=-150.0067&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration - NTSB case key (mKey): 99700 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC19LA027 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99700/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99700 - Page: https://openairdocs.org/ntsb/ANC19LA027 ## Probable cause The pilot’s failure to maintain directional control during a precautionary landing, which resulted in a ground loop. Contributing to the accident was a partial loss of engine power for reasons that could not be determined. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause) - [Airport facilities/design: runway/landing area condition](https://openairdocs.org/ntsb-findings/03017035): Environmental issues › Operating environment · Contributed to outcome - [Performance/control parameters: powerplant parameters](https://openairdocs.org/ntsb-findings/01062050): Aircraft › Aircraft oper/perf/capability · Unknown/Not determined (probable cause) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause) ## Analysis The pilot was conducting a local flight when the engine started to surge and run rough. He attempted to troubleshoot the problem, but was not able to restore engine power and located a precautionary landing site at an abandoned airstrip. During the landing roll, the airplane drifted right, and the right wing impacted vegetation, which resulted in a ground loop and substantial damage to the airplane. A postaccident examination of the engine, airframe, and propeller revealed no anomalies that would have precluded normal operation, and the reason for the partial loss of engine power could not be determined. ## Factual narrative On June 11, 2019, about 2230 Alaska daylight time, a Helio H-391B airplane, N10CJ, sustained substantial damage when it was involved in an accident near Hope, Alaska. The private pilot and pilot-rated passenger were uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that, while flying over a natural gas pipeline, the engine started to surge and run rough, and the engine manifold pressure decreased. He cycled the throttle lever, increased the mixture lever to full rich, and turned on the electric fuel boost pump, but full power was not restored. The pilot-rated passenger pulled the carburetor heat lever out (carburetor heat on) with no effect on engine performance. The pilot was able to maintain altitude, but engine power was limited, so he searched for a precautionary landing site. He located an abandoned airstrip along the pipeline road and performed an approach to the north. The pilot reported that during the approach, he reduced power too late, which resulted in an overshoot of the best landing area, and that the airplane drifted right during the landing. During the landing roll, the right wingtip impacted vegetation, and the airplane ground looped and impacted trees, resulting in substantial damage to the left aileron and both sides of the stabilator. The pilot stated that the engine surged slightly during the takeoff before the accident, but not enough to concern him. About two months before the accident, the airplane experienced a surge and partial loss of power during takeoff. A mechanic inspected the engine and conducted compression tests with no anomalies noted. After the accident, the engine was intact and attached to the airframe with all fuel, oil, ignition and air lines secure. A fuel sample drained from the gascolator contained no contamination and was consistent with aviation fuel. The fuel filter was clear of debris. Continuity of the engine and the flight control system was established. The propeller blades were secure in the hub with no oil leaks observed. The engine started and accelerated smoothly and the propeller control cycled three times with corresponding change in manifold pressure, rpm, and oil pressure. The rpm was advanced to a maximum of 3,400 rpm for 5 seconds with no surges noted. The propeller governor (Hartzell B-3) was removed and bench-tested at a Hartzell facility with no anomalies noted. There was no evidence of any preexisting engine, propeller, or airframe discrepancies that would have precluded normal operation. ## 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 (partial)](https://openairdocs.org/ntsb-events/342) (defining event) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470) ## Aircraft - Registration: [N10CJ](https://openairdocs.org/aircraft/N10CJ), registered now, S/N 099, built 1958 (OpenAirDocs) - Reported make and model: HELIO H391 (B) - Registry model: [Helio H-391B](https://openairdocs.org/model/helio-h-391b) (registry code 4300106) (OpenAirDocs) - Registry engine: [Lycoming GO-435](https://openairdocs.org/engine/lycoming-go-435) (registry code 41520, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 099 - Year built: 1958 - Airframe hours: 4481 - Engines: Lycoming GO-435-C2B2-6 260 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 21, 2018 - Departed: AK73, Nikishka, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; injuries: none; private; airplane ratings: single-engine sea, single-engine land; medical: basicmed, with waivers/limitations; seat: left; flight hours: 1,628 total, 225 in this make and model, 1,628 as pilot in command, 22 in the last 90 days, 4 in the last 30 days, 1 in the last 24 hours - Pilot-rated passenger; age 54; injuries: none; private; airplane ratings: single-engine land, single-engine sea; medical: class 3, with waivers/limitations; seat: right ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 16 knots, gusting 27 - Visibility: 10 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 63 °F, dew point 45 °F - Altimeter: 29.79 inHg - Observed at: PANC, 21 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 20190611006639A](https://openairdocs.org/incident/20190611006639A), Jun 11, 2019: Helio H-391B, Hope, AK, Substantial damage. On June 11, 2019, at 2230 AKDT, N10CJ, a Helio courier H391-B, was substantially damaged when the pilot attempted a precautionary landing at an unmaintained… ## Docket (3 files) The files NTSB released with the investigation on June 18, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99700. 1.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 596 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12166246&FileExtension=pdf&FileName=6120%20master%20LA027_Redacted-Rel.pdf - Pilot record of conversation (item 2, PDF, 2 pages, 178 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12179127&FileExtension=pdf&FileName=Record%20of%20Conversation%20Paul%20Dale%20V3-Rel.pdf - NTSB airframe and engine examination summary (item 3, PDF, 5 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12177187&FileExtension=pdf&FileName=ANC19LA027%20Airframe%20and%20Engine%20Examination%20V2-Rel.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.