# NTSB ERA18LA192: Schweizer 269D, N411HU, Stewartstown, PA, July 14, 2018 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: July 14, 2018, 11:15 local (15:15 UTC) - Place: Stewartstown, PA - Coordinates: 39.796112, -76.646942 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.7961&lon=-76.6469&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 97788 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA18LA192 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/97788/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=97788 - Page: https://openairdocs.org/ntsb/ERA18LA192 ## Probable cause The pilot's inability to maintain yaw control while transitioning to an out of ground effect hover due to a loss of tail rotor effectiveness. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: yaw control](https://openairdocs.org/ntsb-findings/01062024): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Schweizer 269D, 1 case](https://openairdocs.org/ntsb-findings/01062024/cases.md?model=8059501), [All aircraft, 149 cases](https://openairdocs.org/ntsb-findings/01062024/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Schweizer 269D, 2 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=8059501), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach: Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242) (defining event); cases with it: [Schweizer 269D, 1 case](https://openairdocs.org/ntsb-events/242/sequence.md?model=8059501), [All aircraft, 100 cases](https://openairdocs.org/ntsb-events/242/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Schweizer 269D, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=8059501), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that he made an uneventful approach into the 8-to-10 knot wind nearly directly down the runway. While operating the helicopter out of ground effect about 15 to 20 ft above ground level and about 10 to 20 knots, he began to apply left antitorque pedal to start to hover. With wind from the right, the helicopter then started turning clockwise; he applied left antitorque pedal, which did not stop the rotation, and the helicopter completed about 12 turns before impacting the ground. The passenger recalled the helicopter spinning clockwise and coming to rest on its left side. The helicopter sustained substantial damage to the fuselage, horizontal stabilizer, and rotor blades. The pilot did not recall reducing throttle or lowering collective during the accident sequence. Postaccident examination of the tail rotor flight control and drive system revealed no evidence of preimpact failures or malfunctions that would have precluded normal operation. Although the tail rotor control cable tension was about 2 lbs, or about 3%, less than the helicopter manufacturer’s specifications, that discrepancy would not affect operation of the tail rotor. Given this information, it is likely that the pilot was unable to stop the yaw and lost control of the helicopter due to a loss of tail rotor effectiveness. ## Factual narrative On July 14, 2018, about 1115 eastern daylight time, a Schweizer 269D Configuration A, N411HU, was substantially damaged when it was involved in an accident near Stewartstown, Pennsylvania. The pilot and passenger sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that he was flying toward the eastern side of Shoestring Aviation Airfield (0P2), Stewartstown, Pennsylvania, to begin a normal approach to runway 24, with wind from about 230° at about 8 to 10 knots. He reported that the landing approach was uneventful until he attempted to slow the helicopter. While the helicopter was at an airspeed of between 10 to 20 knots about 15 to 20 ft above ground level, he began to apply left antitorque pedal to start to hover. He stated that the helicopter then started turning clockwise; he instinctively applied left antitorque pedal, which did not stop the rotation. He added that he did not recall lowering collective or reducing throttle. The turning accelerated rapidly until the helicopter was spinning in 360° circles. After six to eight complete rotations, the spinning decreased but then accelerated again, with another five to seven turns clockwise until the helicopter impacted the ground. He stated that he did not recall hearing any audible alarms or any change in engine sound. The passenger reported the helicopter began spinning clockwise and then impacted the ground, with the helicopter on its left side. A witness who was located about 750 ft southeast of where the helicopter came to rest reported seeing the helicopter smoothly come to a hover at the end of the runway, remain stationary for more than 5 seconds, then cleanly rotate left while remaining in the hover position. He reported that the rotation did not slow/stop as expected after 90°. Instead, the left rotation continued an estimated six to seven turns while the helicopter maintained altitude and position. He reported that the turns stopped for about 1 second, then began again, with the helicopter drifting backward to the east and losing altitude. He reported that he did not discern the direction of the second set of turns but that a review of video taken by a nearby individual noted the second set of turns was to the right. He reported that the entire time he saw the helicopter, the engine sound was constant with no variation. Postaccident examination of the helicopter revealed substantial damage to the main and tail rotor blades as well as the left fuselage and horizontal stabilizer. Antitorque control continuity was confirmed from the controls at each seat to the tail rotor. The tail rotor gearbox was firmly attached to its tailboom mounting frame, and the tail rotor gearbox and tail rotor swashplate operated smoothly when rotated by hand. There was no damage noted to the tail rotor pitch change mechanism. The tail rotor blades were manipulated by hand, and the control linkages and mechanisms respondedappropriately with no binding noted. The transmission rotated smoothly with corresponding rotation of the main rotor head and tail rotor gearbox. The tail rotor control system was tested by holding the tail rotor blades while the left and right antitorque pedals were manipulated by hand through their full range of motion against their respective stops; no binding was noted, with changes in pitch in the tail rotor blades consistent with the antitorque pedal movements. A tension check of the tail rotor control cables revealed a reading between 58 and 59 lbs (the helicopter’s maintenance manual specified 60 to 65 lbs). According to a helicopter manufacturer representative, the variation in required to actual measured cable tension would not have an effect on the tail rotor control system's capability to provide adequate control of the helicopter. The wind conditions reported at York Airport, York, Pennsylvania, which was located about 13 nautical miles northwest of the accident, were from 230° at 8 knots. Review of the Pilot's Flight Manual for the helicopter make and model revealed the main rotor diameter was about 28 ft. According to Federal Aviation Administration Advisory Circular (AC) 90-95, “Unanticipated Right Yaw in Helicopters,” loss of tail rotor effectiveness (LTE) is a critical, low-speed aerodynamic flight characteristic that could result in an uncommanded rapid yaw rate that does not subside of its own accord and, if not corrected, could result in the loss of helicopter control. The AC also states, "LTE is not related to a maintenance malfunction and may occur in varying degrees in all single main rotor helicopters at airspeeds less than 30 knots." ## Aircraft - Registration: [N411HU](https://openairdocs.org/aircraft/N411HU), registered now, S/N 0040, built 2003 (OpenAirDocs) - Reported make and model: Schweizer 269D (CONFIG A) - Registry model: [Schweizer 269D](https://openairdocs.org/model/schweizer-269d) (registry code 8059501) (OpenAirDocs) - Registry engine: [Rolls-Royce 250 20&30 series](https://openairdocs.org/engine/rolls-royce-250-20-30-series) (registry code 54584, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 0040 - Year built: 2003 - Airframe hours: 2710.2 - Engines: Rolls-Royce 250-C20W 232 horsepower turbo shaft - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 24, 2017, 18 hours before - Departed: MTN, Baltimore, MD - Destination: 0P2, Stewartstown, PA - Airport: 0P2, Shoestring Aviation Airfield, runway 24U, 1,000 × 100 ft, grass/turf - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: minor; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review May 11, 2018; seat: left; restraint: 4-point; flight hours: 575 total, 75 in this make and model, 471 as pilot in command, 11 in the last 90 days, 5 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 63 °F - Altimeter: 30.15 inHg - Turbulence: Light - Observed at: THV, 13 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 20180714011209A](https://openairdocs.org/incident/20180714011209A), Jul 14, 2018: Schweizer 269D CONFIG A, Stewartstown, PA, Substantial damage. [privacy data omitted] Was flying N411HU a Schweizer 269D with one passenger at Shoestring Airport (0P2). After approach on runway 24 and near the intersection… ## Docket (10 files) The files NTSB released with the investigation on April 5, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=97788. 33.2 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 6.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=6940826&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Passenger statements (item 2, PDF, 2 pages, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=6940656&FileExtension=pdf&FileName=Passenger%20Statement-Rel.pdf - Witness statement, annotated pictures and diagram (item 3, PDF, 3 pages, 5.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=6944219&FileExtension=pdf&FileName=Witness%20Statement,%20and%20Annotated%20Pictures%20and%20Diagram-Rel.pdf - Excerpts from pilot's flight manual (item 4, PDF, 4 pages, 645 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=6949406&FileExtension=pdf&FileName=Excerpts%20from%20Pilot%27s%20Flight%20Manual-Rel.pdf - Excerpt from airframe maintenance records (item 5, PDF, 1 page, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=6948849&FileExtension=pdf&FileName=Airframe%20Annual%20Maintenance%20Record%20Entry_Redacted-Rel.pdf - FAA inspector statement (item 6, PDF, 3 pages, 10.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=6877739&FileExtension=pdf&FileName=FAA%20Inspector%20Statement%20N411HU%20Insp%20Stmnt%20rev3_Redacted-Rel.pdf - Record of NTSB conversations (item 7, PDF, 7 pages, 78 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9380806&FileExtension=pdf&FileName=Record%20of%20NTSB%20Conversations_Redacted-Rel.pdf - Memorandum for record - antitorque control cable tension test results (item 8, PDF, 3 pages, 5.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9574505&FileExtension=pdf&FileName=Memorandum%20For%20Record%20-Antitorque%20control%20cable%20Tension%20Test%20Results_Redacted-Rel.pdf - Investigative photograph (item 9, PDF, 1 page, 1 photo, 251 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9385265&FileExtension=pdf&FileName=Investigative%20Photograph-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 10, PDF, 1 page, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9382417&FileExtension=pdf&FileName=Fully%20Executed%20Wreckage%20Release%20Form_Redacted-Rel.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.