CEN20LA330 · Robinson R44 II
Cedar Ridge Aviation Robinson R44 II · Accident: system/component malfunction/failure (non-power) while maneuvering
From Logan, IA to an unrecorded destination
Event
- NTSB case
- CEN20LA330
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Robinson R44 II
- Aircraft type
- Robinson R44
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N89LA
- Operator
- Cedar Ridge Aviation
- Onboard fatalities
- Unknown
- Route
- From Logan, IATo not recorded
- Aircraft age
- About 15 years (built 2005)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 137: Agricultural
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · low-altitude flying
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- System/component malfunction/failure (non-power)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft propeller/rotor
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN20LA330
- Event ID
- 20200809X02446
- Case number
- CEN20LA330
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 1191a0b8143e27a346c94b225eb25d81c693935e9e034ca8b5fd84840a04d301; retrieved 2026-09-16T12:25:48.613Z.