# NTSB ANC13LA079: Piper PA-18-150, N44RT, Paxson, AK, August 13, 2013 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 13, 2013, 12:40 local (20:40 UTC) - Place: Paxson, AK - Coordinates: 62.956665, -146.384719 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=62.9567&lon=-146.3847&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report September 29, 2014 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA Anchorage FSDO - NTSB case key (mKey): 87777 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC13LA079 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/87777/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=87777 - Page: https://openairdocs.org/ntsb/ANC13LA079 ## Probable cause The partial loss of engine power due to a loose throttle cable clamp. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Piper PA-18-150, 3 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=7101828), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Engine controls: power lever](https://openairdocs.org/ntsb-findings/01057603): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Piper PA-18-150, 1 case](https://openairdocs.org/ntsb-findings/01057603/cases.md?model=7101828), [All aircraft, 95 cases](https://openairdocs.org/ntsb-findings/01057603/cases.md) - [Runway/land/takeoff/taxi surface](https://openairdocs.org/ntsb-findings/03023000): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Piper PA-18-150, 11 cases](https://openairdocs.org/ntsb-findings/03023000/cases.md?model=7101828), [All aircraft, 253 cases](https://openairdocs.org/ntsb-findings/03023000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Piper PA-18-150, 2 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=7101828), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Piper PA-18-150, 13 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7101828), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Piper PA-18-150, 115 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7101828), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The private pilot reported that she was on a cross-country flight in a float-equipped airplane, and that, about 20 minutes into the flight, the engine rpm suddenly dropped to idle. She moved the throttle forward, and the engine momentarily responded, but it again dropped to idle power. She switched fuel tanks, but the engine still did not respond, so she initiated a forced landing to brush-covered tundra. During the forced landing, the airplane nosed over, which caused substantial damage to the wings, fuselage, and empennage. Examination of the engine revealed that the clamp that secures the throttle cable was loose, which allowed the throttle cable housing to move inside the clamp. The engine was started without tightening the throttle cable clamp, and it operated normally through various power settings. Given the loose throttle cable clamp and the pilot's account of the accident sequence, it is likely that the throttle cable housing was free to move when the throttle lever moved, which limited the amount of throttle authority available to the pilot. ## Factual narrative On August 13, 2013, about 1240 Alaska daylight time, a float-equipped Piper PA-18-150 airplane, N44RT, sustained substantial damage during a forced landing following a partial loss of engine power near Paxson, Alaska. The private pilot and one passenger were not injured. The airplane was registered to, and operated by the pilot as a visual flight rules personal cross-country flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from Tangle Lakes, Alaska about 1220, destined to Anchorage, Alaska. In a written statement to the National Transportation Safety Board (NTSB), the pilot said that approximately 20 minutes into the flight, the engine suddenly went to idle RPM. She moved the throttle forward and received a momentary response, but the engine again went to idle power. She switched fuel tanks, and the engine still did not respond, so she initiated a forced landing in an area of brush covered tundra. During the forced landing, the airplane nosed over, sustaining substantial damage to the wings, fuselage, and empennage. The closest official weather observation station is located at the Gulkana Airport, Gulkana, Alaska, about 52 miles south of the accident site. At 1253, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind, 160 degrees (true) at 6 knots; visibility, 10 statute miles; clouds and sky condition, clear; temperature, 72 degrees F; dew point, 48 degrees F; altimeter, 29.95 inHg. On August 20, the NTSB investigator-in-charge, along with an inspector from the Anchorage Flight Standards District Office, examined the airplane at the facilities of Alaska Claims Services, Inc., Wasilla, Alaska. The examination revealed no preaccident anomalies with the airframe that would have precluded normal operation. Examination of the Lycoming O-320-B2B engine revealed that the throttle cable clamp was loose around the throttle cable, allowing the cable housing to move as well as the cable to move inside the housing. The airplane was secured and the engine was started and run for approximately 10 minutes through various power settings without anomaly. The airplane underwent an annual inspection on June 27, 2013, and had flown approximately 10 hours since being returned to service. The throttle cable clamp that was used to secure the throttle cable in the airplane is known in the community to loosen and allow the cable to slip. While there is no requirement to do so, many Piper PA-18 operators and mechanics use safety wire on both sides of the clamp to ensure security of the cable. The clamp on the accident airplane was not secured with safety wire. ## Aircraft - Registration: [N44RT](https://openairdocs.org/aircraft/N44RT), registered now, S/N 18-8927, built 1971 (OpenAirDocs) - Reported make and model: PIPER PA-18-150 - 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: 18-8927 - Airframe hours: 2420 - Engines: LYCOMING O-320 SERIES 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 27, 2013, 10 hours before - Departed: Tangle Lakes, AK - Destination: PALH, Anchorage, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: none; private; airplane ratings: single-engine sea, single-engine land; medical: class 3, with waivers/limitations; last flight review June 11, 2013; seat: front; restraint: 4-point; flight hours: 397 total, 183 in this make and model, 4 in the last 90 days, 4 in the last 30 days, 1 in the last 24 hours - Pilot-rated passenger; age 68; injuries: none; commercial; airplane ratings: single-engine sea, single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review June 12, 2013; seat: rear; restraint: 4-point; flight hours: 1,525 total, 1,525 in this make and model, 16 in the last 90 days, 8 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 48 °F - Altimeter: 29.95 inHg - Observed at: PAGK, 54 nm away ## Docket (2 files) The files NTSB released with the investigation on August 6, 2014, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=87777. 618 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 571 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40414647&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation (item 2, .PDF, 47 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40414648&FileExtension=.PDF&FileName=Record%20of%20Conversation-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.