# NTSB CEN20LA330: Robinson R44, N89LA, Logan, IA, August 8, 2020 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: August 8, 2020, 18:45 local (23:45 UTC) - Place: Logan, IA - Coordinates: 41.631665, -95.793459 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.6317&lon=-95.7935&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Lycoming Engines, Robinson Helicopter Company, FAA Des Moines FSDO - NTSB case key (mKey): 101766 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20LA330 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101766/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101766 - Page: https://openairdocs.org/ntsb/CEN20LA330 ## Probable cause The failure of the lower actuator bearing support brackets, which resulted in the misalignment of the clutch actuator, a loss of belt tension on the main rotor drive system, and a subsequent forced landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Main rotor drive](https://openairdocs.org/ntsb-findings/01046300): Aircraft › Aircraft propeller/rotor · Not serviced/maintained (probable cause); cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-findings/01046300/cases.md?model=7640122), [All aircraft, 15 cases](https://openairdocs.org/ntsb-findings/01046300/cases.md) - [Main rotor drive](https://openairdocs.org/ntsb-findings/01046300): Aircraft › Aircraft propeller/rotor · Failure (probable cause); cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-findings/01046300/cases.md?model=7640122), [All aircraft, 15 cases](https://openairdocs.org/ntsb-findings/01046300/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220); cases with it: [Robinson Helicopter R44 II, 45 cases](https://openairdocs.org/ntsb-events/220/sequence.md?model=7640122), [All aircraft, 780 cases](https://openairdocs.org/ntsb-events/220/sequence.md) - [Maneuvering-low-alt flying: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Robinson Helicopter R44 II, 9 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=7640122), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Maneuvering-low-alt flying: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Robinson Helicopter R44 II, 24 cases](https://openairdocs.org/ntsb-events/060/sequence.md?model=7640122), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Maneuvering-low-alt flying: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Robinson Helicopter R44 II, 26 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=7640122), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-flare/touchdown: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Robinson Helicopter R44 II, 16 cases](https://openairdocs.org/ntsb-events/490/sequence.md?model=7640122), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis The commercial pilot had just completed several spray runs in the helicopter and was turning to line up for another run, when he heard the engine emit a "pop" noise. The helicopter yawed “violently,” the engine rpm increased, and the rotor rpm decreased, which caused both the low rotor rpm horn and light to activate. The pilot initiated an autorotation to a cornfield, where the helicopter impacted an area of rising terrain and came to rest on its right side. The helicopter sustained substantial damage to the fuselage. A postaccident examination of the airframe revealed that all four V-belts that drive the rotor system were displaced from their grooves. Small areas of damage were visible in one belt. The lower bearing brackets (also known as A185 brackets) were separated from the scroll and the belt tension actuator had rotated out of position. The mating surface of the brackets and the scroll were polished smooth, and the edges of the brackets had dug into the scroll. The attaching rivets were sheared flush with the mating surface of the brackets. The rivet holes in the scroll were elongated in the direction of engine rotation. The bracket backing plates were not present. The belt tension actuator had fractured just below the upper gear housing. It is likely that, over time, the lower brackets supporting the lower actuator bearing became loose during flight operations and sheared the rivets, which allowed the actuator bearing to shift and led to a subsequent misalignment of the clutch actuator. The misalignment of the clutch actuator resulted in the loss of belt tension between the engine and the main rotor drive system. The pilot’s report of an unusual noise, the nose yaw, and an increase of engine rpm and a decrease in rotor rpm was consistent with a drive system failure. A review of the airframe maintenance logbooks showed no evidence of compliance with the helicopter manufacturer’s service bulletin RHC SB-94 and service letter RHC SL-61A. RHC SB-94 directs the inspection of the A185 brackets for evidence of fretting or looseness. RHC SL-61A directs actions to be performed whenever looseness of an A185 bracket is detected and whenever the upper or lower scroll was removed. The FAA does not require compliance with RHC SB-94 and RHC SL-61A for 14 CFR Part 91 and 14 CFR Part 137 operations. ## Factual narrative On August 8, 2020, about 1845 central daylight time, a Robinson Helicopter Company (RHC) R44II helicopter, N89LA, sustained substantial damage when it was involved in an accident near Logan, Iowa. The pilot sustained serious injuries. The helicopter was operated as a Title 14 Code of Federal Regulations (CFR) Part 137 aerial application flight. The pilot was assigned to spray a 380-acre cornfield. The pilot had just completed several spray runs and was turning to line up for another run, when he heard the engine emit a "pop" noise. The helicopter yawed “violently,” the engine rpm increased, and the rotor rpm decreased which caused both the low rotor rpm horn and light to activate. The pilot lowered the collective, entered “pedal correction,” and slightly pitched the nose of the helicopter back without “bleeding much airspeed off.” The helicopter continued to glide forward and descended toward a corn field. The pilot initiated a gradual flare and as the helicopter began to settle, he increased the flare. The helicopter impacted an area of rising terrain and came to rest on its right side. The helicopter sustained substantial damage to the fuselage. The RHC R44 Series Pilot’s Operating Handbook states that a drive system failure may be indicated by an unusual noise or vibration, nose right or left yaw, or increasing engine rpm with decreasing rotor rpm. A postaccident examination of the airframe revealed that all four V-belts that drive the rotor system were displaced from their grooves. Small areas of damage were visible in one belt. The lower and upper belt tension actuator support bearing rotated smoothly. The lower bearing brackets (also known as A185 brackets) were separated from the scroll and the belt tension actuator had rotated out of position. The mating surface of the brackets and the scroll were polished smooth, and the edges of the brackets had dug into the scroll. The attaching rivets were sheared flush with the mating surface of the brackets. The rivet holes in the scroll were elongated in the direction of engine rotation. The bracket backing plates were not present. The belt tension actuator had fractured just below the upper gear housing. RHC SB-94, dated June 8, 2017, is addressed to R44 series owners, operators, and maintenance personnel. RHC SB-94 directs the inspection of the A185 brackets for evidence of fretting or looseness. According to the SB, “loose brackets can allow lower bearing to misalign resulting in belt-tension actuator damage.” The compliance procedure is to visually inspect the A185 brackets and attaching rivets for evidence of fretting or looseness, and on the lower A185 bracket, apply torque seal in a vertical stripe across both outboard rivets to the lower scroll to highlight movement for future inspections. RHC SL-61A, dated July 21, 2017, is addressed to R44 series owners, operators, and maintenance personnel. The RHC SL directs actions to be performed whenever looseness of an A185 bracket is detected andwhenever the upper or lower scroll was removed. To comply with SL-61A, a third middle rivet is to be placed on each upper bracket. The RHC R44 Series Maintenance Manual, states that a 100-hour inspection is required of the lower actuator bearing, including inspection of the fiberglass scroll area at the bearing attachment brackets for signs of cracking, and the lower bearing brackets for signs of looseness and wear. A review of the airframe maintenance logbooks showed no compliance with RHC Service Bulletin (SB)-94 nor RHC Service Letter (SL)-61A. Compliance with RHC SB-94 and RHC SL-61A is not mandated by the Federal Aviation Administration for 14 CFR Part 91 and 14 CFR Part 137 operations. ## Aircraft - Registration: [N89LA](https://openairdocs.org/deregistered/N89LA-2020-11-25), registration cancelled 2020-11-25, S/N 10984, built 2005 (OpenAirDocs) - Reported make and model: Robinson R44 (II) - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 10984 - Year built: 2005 - Airframe hours: 2017.2 - Engines: Lycoming Engines IO-540-AE1A5 260 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Cedar Ridge Aviation, LLC, doing business as Cedar Ridge Aviation, LLC - Registered owner: Mills County Choppers Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, September 6, 2020, 74.9 hours before - Departed: Logan, IA - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; injuries: serious; commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review June 6, 2019; seat: right; restraint: 3-point; flight hours: 2,800 total, 150 in this make and model, 2,650 as pilot in command, 250 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: 3,800 ft overcast - Temperature: 84 °F, dew point 73 °F - Altimeter: 29.92 inHg - Observed at: KTQE, 19 nm away - METAR: KTQE 082354Z AUTO 15005KT 10SM OVC038 29/23 A2992 RMK AO2 SLP118 T02890233 10311 20283 51005 ## 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 20200808016139A](https://openairdocs.org/incident/20200808016139A), Aug 8, 2020: Robinson Helicopter Company R44 II, Logan, IA, Destroyed. Pilot noticed engine and rotor RPM issues associated with a "popping" noise. Helicopter entered power on decent, pilot flared and impacted the ground hard,… ## Docket (6 files) The files NTSB released with the investigation on April 21, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101766. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 833 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12675593&FileExtension=pdf&FileName=NTSB%20Form%206120_1%20Redacted-Rel.pdf - Accident photographs (item 2, PDF, 7 pages, 7.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12675979&FileExtension=pdf&FileName=Accident%20Photographs-Rel.pdf - Robinson helicopter company examination report (item 3, PDF, 148 pages, 14.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12676572&FileExtension=pdf&FileName=RHC%20Examination%20Report%20Redacted-Rel.pdf - Additional statements and records (item 4, PDF, 5 pages, 63.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12682090&FileExtension=pdf&FileName=Additional%20Statements%20and%20Records%20Redacted-Rel.pdf - Robinson helicopter company documents (item 5, PDF, 16 pages, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12676029&FileExtension=pdf&FileName=RHC%20Documents%20Redacted-Rel.pdf - NTSB party member forms (item 6, PDF, 2 pages): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12676927&FileExtension=pdf&FileName=NTSB%20Party%20Member%20Forms%20Redacted-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.