# NTSB WPR17LA093: Schweizer 269C, N521AR, Coolidge, AZ, April 27, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 27, 2017, 09:45 local (16:45 UTC) - Place: Coolidge, AZ - Coordinates: 32.977779, -111.517501 - Nearby events: https://openairdocs.org/map.md?lat=32.9778&lon=-111.5175&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: Minor injuries - Injuries: 1 minor - Status: Completed, report July 5, 2018 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration, Lycoming Engines - NTSB case key (mKey): 95082 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR17LA093 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95082/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95082 - Page: https://openairdocs.org/ntsb/WPR17LA093 ## Probable cause A partial loss of engine power due to separation of the throttle cable. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine controls](https://openairdocs.org/ntsb-findings/01057600): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Schweizer 269C, 1 case](https://openairdocs.org/ntsb-findings/01057600/cases.md?model=8059502), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/01057600/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 (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Schweizer 269C, 5 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=8059502), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Schweizer 269C, 17 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=8059502), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis The private pilot stated that the helicopter was in cruise flight when he noted a change in engine sound and a corresponding loss of engine rpm. He checked the throttle to ensure that it had not rolled back; it had not. He then attempted to roll the throttle on, then off; however, there was no response from the engine. The pilot chose to perform a precautionary landing, during which the helicopter landed hard and rolled over. Postaccident engine examination revealed that the throttle arm at the fuel injector servo would not move when input was applied at the collective throttle grip; the cable had separated within its housing. The cable housing was securely mounted at each end and exhibited no evidence of damage. The cable was removed from the housing; it was worn and had separated near the servo end about 1 inch from where it swaged to the rigid portion in an area where the cable housing was slightly bent. This bend in the housing likely resulted in the cable rubbing on the interior housing wall and, over time, led to the cable's the failure and separation, and the subsequent partial loss of engine power. Examination of the helicopter maintenance logs did not provide a history of the cable maintenance; however, the cable was not subject to any hourly or calendar life limits, and there was no way to disassemble the housing to facilitate an internal examination of the cable. The cause of the bend in the housing could not be determined. ## Factual narrative On April 27, 2017, about 0945 mountain standard time, a Schweizer 269C, N521AR, was substantially damaged subsequent to a hard landing near Coolidge, Arizona. The helicopter was operated by Canyon State Aero, LLC under the provisions of 14 Code of Federal Regulations Part 91. The private pilot, the sole occupant, sustained minor injuries. The cross-country instructional flight departed Falcon Field Airport (FFZ), Mesa, Arizona, about 0915 with a planned destination of Coolidge, Arizona. Visual meteorological conditions prevailed and no flight plan had been filed. The pilot reported that the purpose of the flight was training in preparation towards a commercial certificate. While traveling south about 2,000 to 2,100 ft mean sea level, and 65 to 70 knots airspeed, he scanned manifold pressure, altitude, airspeed and engine/rotor rpm. Everything appeared normal. Shortly thereafter, he noticed a change in the sound of the engine, and that the rpm gauge indicated a drop. The pilot checked the throttle to make sure it had not rolled back out of the friction. He then rolled the throttle further, however there was no response. He rolled it slightly off and again there was no response. The helicopter was close to the ground at this time, so he chose a spot to land on the open desert floor. Just before touchdown, he flared and the helicopter impacted the ground hard and rolled over onto its right side. During the postaccident engine examination, the bottom spark plugs were removed. According to the Champion Spark Plugs Check-A-Plug Chart AV-27, the spark plug electrodes displayed coloration consistent with normal wear. The crankshaft was rotated by hand with no binding noted. Thumb compression was observed in each cylinder. Mechanical continuity was established to the accessory section. During the engine control continuity check, the throttle arm at the fuel injector servo would not move when a corresponding input was applied at the collective throttle grip. Further examination revealed that the throttle cable was found to have separated within the cable housing, and in an area where the cable housing was slightly bent. The cable housing was securely mounted at each end and exhibited no visual evidence that it had been damaged during the accident sequence. The cable was removed from the housing. There was no kinking or evidence of binding observed. The cable was found worn and had separated near the servo end about 1 inch from where it swaged to the rigid portion. The engine was then prepared for an engine run. The engine was started with the starter using standard procedures. Once the engine was at operating temperature, the throttle was advanced to an rpm to facilitate a magneto check utilizing the cockpit mounted ignition switch. Both magnetos operated at each of their respective switch detents and within manufacturers specifications. The engine ran smoothly throughout the operational check. The engine manufacturer participant reported that the subjectcable is not controlled by any hourly or calendar life limits, and there was no way to disassemble the cable from the housing to facilitate an internal examination. Further examination of the helicopter maintenance logbooks did not provide a history for the subject cable. ## Aircraft - Registration: [N521AR](https://openairdocs.org/deregistered/N521AR-2019-03-12), registration cancelled 2019-03-12, S/N S1785, built 1999 (OpenAirDocs) - Reported make and model: SCHWEIZER 269C (UNDESIGNAT) - Registry model: [Schweizer 269C](https://openairdocs.org/model/schweizer-269c) (registry code 8059502) (OpenAirDocs) - Registry engine: [Lycoming HIO-360-D1A](https://openairdocs.org/engine/lycoming-hio-360-d1a) (registry code 41893, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: S1785 - Year built: 1999 - Airframe hours: 4147.8 - Engines: Lycoming HIO360-D1A 190 hp reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Canyon State Aero LLC - Registered owner: Canyon State Aero LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 17, 2017, 14 hours before - Departed: FFZ, MESA, AZ - Destination: P08, COOLIDGE, AZ ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: minor; private; instrument ratings: helicopter; medical: class 2, without waivers/limitations; seat: left; restraint: 4-point; flight hours: 156 total, 130 in this make and model, 6 as pilot in command, 76 in the last 90 days, 25 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F - Observed at: KP08, 5 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 20170427021499A](https://openairdocs.org/incident/20170427021499A), Apr 27, 2017: Schweizer 269C, Florance, AZ, Substantial damage. On April 27, 2017 at approximately 1000 MST, N521AR, a schweitzer 269C helicopter, serial number S1785, made a hard landing in a cow pasture near florence, AZ.… ## Docket (5 files) The files NTSB released with the investigation on January 2, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95082. 5.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459092&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation (item 2, .PDF, 348 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459093&FileExtension=.PDF&FileName=Record%20of%20Conversation-Master.PDF - FAA Report of Exam (item 3, .PDF, 297 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459094&FileExtension=.PDF&FileName=FAA%20Report%20of%20Exam-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 4, .PDF, 273 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459095&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Accident Photos (item 5, .PDF, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40459096&FileExtension=.PDF&FileName=Accident%20Photos-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.