# NTSB ERA22LA256: Robinson Helicopter R44, N132TC, North Myrtle Beach, SC, May 26, 2022 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: May 26, 2022, 13:40 local (17:40 UTC) - Place: North Myrtle Beach, SC - Coordinates: 33.808099, -78.728463 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.8081&lon=-78.7285&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-hover: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: Robinson Helicopters, FAA/FSDO - SAIBs cited in the narratives: [SAIB AIR-22-08](https://openairdocs.org/saib/AIR-22-08) (OpenAirDocs) - NTSB case key (mKey): 105177 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA22LA256 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105177/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105177 - Page: https://openairdocs.org/ntsb/ERA22LA256 ## Probable cause The fractured attachment lug on the forward clutch shaft yoke due to fatigue failure with multiple origins. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Main rotor drive: engine/transmission coupling](https://openairdocs.org/ntsb-findings/01046310): Aircraft › Aircraft propeller/rotor · Fatigue/wear/corrosion (probable cause); cases with it: [Robinson Helicopter R44, 1 case](https://openairdocs.org/ntsb-findings/01046310/cases.md?model=7640120), [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/01046310/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-hover: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Robinson Helicopter R44, 7 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=7640120), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) ## Analysis Seconds after liftoff to a hover, the helicopter began to “aggressively shudder.” Loud, rapid reports were heard, and the nose of the helicopter yawed to the left. The instructor assumed control of the helicopter, closed the throttle, and performed an autorotation from a hover, landing the helicopter upright on its skids; however, the airframe sustained substantial damage. The instructor completed an engine shutdown, egressed the helicopter, and noticed that the main rotor was still turning while the tail rotor remained stationary. A cursory examination of the helicopter revealed that the clutch shaft yoke fractured at one of its two bolt lugs where the yoke attached to the flex plate. All other damage depicted appeared to be impact damage from the rotating assemblies left unsecured by the fractured lug. Examination of the damaged yoke and flexplate in the NTSB materials laboratory revealed a fractured attachment lug on the forward clutch shaft yoke due to fatigue failure with multiple origins. ## Factual narrative On May 26, 2022, about 1340 eastern daylight time, a Robinson R44 helicopter, N132TC, operated by High Tide Helicopters LLC, was substantially damaged when it was involved in an accident near North Myrtle Beach, South Carolina. The flight instructor and the student pilot were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. According to the flight instructor, the student pilot performed a visual approach, which he terminated at a hover. The student landed the helicopter and then performed a takeoff to a hover. Seconds later, the helicopter began to “aggressively shudder.” Loud, rapid reports were heard, and the nose of the helicopter yawed to the left. The instructor assumed control of the helicopter, closed the throttle, and performed an autorotation from a hover, landing the helicopter upright on its skids. The event resulted in substantial damage to the airframe. The instructor completed an engine shutdown, egressed the helicopter, and noticed that the main rotor was still turning while the tail rotor remained stationary, and recorded the turning rotor with his telephone. A cursory examination of the helicopter revealed no visible exterior damage and “bits” of engine/transmission drive belts on the runway surface. A postaccident examination revealed that the clutch shaft yoke fractured at one of its two bolt lugs where the yoke attached to the flex plate. All other damage depicted appeared to be impact damage from the rotating assemblies left unsecured by the fractured lug. The fractured and separated lug piece from the yoke was recovered and retained for further examination, along with the components of the flex plate and yoke assemblies. Examination of the fractured surfaces of the accident bolt lug by an NTSB materials engineer revealed signatures consistent with fatigue. According to his report, “The fracture faces exhibited contact damage and gross mechanical distortion; however, two fatigue cracks were observed. One fatigue crack nucleated at the bolt hole bore chamfer at the outer periphery on the flex plate side. The fracture faces exhibited contact damage and progressed towards the shaft side of the lug. Fatigue crack progression marks were observed over about 80% of the fracture surface. A second fatigue crack nucleated under the washer of the mounting bolt on the flex plate side of the lug. The crack progressed through the lug thickness towards the shaft side of the lug and outwards towards the free surface of the lug. Fatigue crack progression marks were present over about 90% of the fracture surface.” Figure 1 Image of the as-received evidence with fractured lug in top center of frame. (NTSB) Examination of the nucleation sites did not reveal any crack initiation precursors, such as damage, inclusions (foreign object damage), or corrosion. The yoke-to-flex plate clamping surfaces between the attachment hardware, the yokes, and the lugs were clean and presented nopaint, primer, or inclusion. The actual torque values applied to the attachment hardware could not be determined. On June 21, 2021, the Australian Transport Safety Bureau (ATSB) had published a Safety Advisor Notice titled, R44 helicopter drive train failure, in which the circumstances and the damage described and depicted matched that of the accident helicopter. Figure 2 Fractured Clutch Shaft Yoke (Source: ATSB) On April 11, 2022, the Federal Aviation Administration published Special Airworthiness Information Bulletin (SAIB), AIR-22-08, Main Rotor Drive System, Tail Rotor Drive System to echo the Australians’ safety concerns and safety message, as such an event had not been reported in the United States or by any U.S. operators before that date. ## Aircraft - Registration: [N132TC](https://openairdocs.org/aircraft/N132TC), registered now, S/N 1259, built 2002 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER R44 - Registry model: [Robinson Helicopter R44](https://openairdocs.org/model/robinson-helicopter-r44) (registry code 7640120) (OpenAirDocs) - Registry engine: [Lycoming O-540-F1B5](https://openairdocs.org/engine/lycoming-o-540-f1b5) (registry code 42353, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 1259 - Year built: 2002 - Airframe hours: 3711 - Engines: Lycoming O-540 F1B5 260 hp reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: High Tide Helicopters LLC - Registered owner: N132tc LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 13, 2022, 30 hours before - Departed: SUT, Southport, NC - Destination: Same as departure - Airport: CRE, Grand Strand, runway 05, 5,997 × 100 ft, concrete - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 31; injuries: none; commercial, private, flight instructor; airplane ratings: single-engine land; medical: class 1, without waivers/limitations; seat: left; restraint: 4-point; flight hours: 1,240 total, 1,048 in this make and model, 1,150 as pilot in command, 167 in the last 90 days, 68 in the last 30 days, 1 in the last 24 hours - Student pilot; age 26; injuries: none; student; medical: unknown; seat: right; restraint: 4-point; flight hours: 34.2 total, 32.2 in this make and model, 1.3 as pilot in command, 32.2 in the last 90 days, 12.3 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 68 °F - Altimeter: 30.17 inHg - Observed at: KCRE, 1 nm away - METAR: KCRE 261753Z 11009KT 10SM CLR 24/20 A3017 RMK AO1 SLP215 T02440200 10250 20183 57012 ## 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 20220526008639A](https://openairdocs.org/incident/20220526008639A), May 26, 2022: Robinson Helicopter R44, North Myrtle Be, SC, Substantial damage. After landing on runway 5 at cre the student lifted the helicopter into a hover. A loud bang was heard and the instructor took control and put the helicopter… ## Docket (8 files) The files NTSB released with the investigation on March 28, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105177. 16.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16598883&FileExtension=pdf&FileName=6120%20completed%20N132TC_Redacted-Rel.pdf - Pilot's statement (item 2, PDF, 1 page, 491 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16599149&FileExtension=pdf&FileName=Tew%20Signed%20Incident%20Report_Redacted-Rel.pdf - View of turning main rotor and stopped tail rotor (operator) (item 3, MOV, 495 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16599196&FileExtension=mov&FileName=Video%20II-Rel.mov - Manufacturer's parts diagram of yoke and flexplate (item 4, PDF, 1 page, 87 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16611237&FileExtension=pdf&FileName=Robinson%20Parts%20Diagram_Redacted-Rel.pdf - Photo array (item 5, PDF, 4 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16599206&FileExtension=pdf&FileName=Photo%20Array%2022LA256-Rel.pdf - Materials laboratory factual report 22-050 (item 6, PDF, 16 pages, 14 photos, 11.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14152943&FileExtension=pdf&FileName=Materials%20Laboratory%20Factual%20Report%2022-050-Rel.pdf - Safety advisory notice (atsb) (item 7, PDF, 2 pages, 466 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16599169&FileExtension=pdf&FileName=ao-2020-064-san-Rel.pdf - Special airworthiness information bulletin (FAA) (item 8, PDF, 2 pages, 204 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16599216&FileExtension=pdf&FileName=AIR-22-08-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.