# NTSB CEN19LA250: Robinson Helicopter R44 II, N440EM, Lyons, NE, August 3, 2019 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: August 3, 2019, 15:05 local (20:05 UTC) - Place: Lyons, NE - Coordinates: 41.9375, -96.473052 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.9375&lon=-96.4731&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Federal Aviation Administration; Lincoln FSDO - NTSB case key (mKey): 99989 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19LA250 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99989/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99989 - Page: https://openairdocs.org/ntsb/CEN19LA250 ## Probable cause The engine's low cylinder compression, which resulted in low rotor rpm and a subsequent dynamic rollover following landing on soft terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Robinson Helicopter R44 II, 2 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=7640122), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Robinson Helicopter R44 II, 4 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=7640122), [All aircraft, 264 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Robinson Helicopter R44 II, 13 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7640122), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: 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) - [Post-impact: Dynamic rollover](https://openairdocs.org/ntsb-events/231); cases with it: [Robinson Helicopter R44 II, 17 cases](https://openairdocs.org/ntsb-events/231/sequence.md?model=7640122), [All aircraft, 161 cases](https://openairdocs.org/ntsb-events/231/sequence.md) ## Analysis The airline transport pilot of the agricultural aerial application flight stated that as the helicopter entered the field to be sprayed, the low rotor rpm annunciation sounded. He attempted to recover rotor rpm, but the rpm continued to decay rapidly. He then used the remaining rotor rpm to cushion a landing onto the field. As the helicopter touched down, it slid about 150-200 ft before the skid dug into soft dirt and the helicopter rolled over. Post-accident examination of the engine by the operator revealed that the no. 6 cylinder had more leakage/lower compression than the previous 100-hour recorded compression checks. Reduced compression on one or more cylinders would have reduced excess power available to maintain a rotor RPM and altitude. ## Factual narrative On August 3, 2019, at 1615 central daylight time, a Robinson Helicopter Company R44 II helicopter, N440EM, experienced a loss of engine power during an aerial application of a field near Lyons, Nebraska. The helicopter impacted the ground during an attempted recovery by the pilot. The helicopter sustained substantial damage. The airline transport pilot received minor injuries. The helicopter was registered to an individual and operated by Wallin Agricultural Aviation under Title 14 Code of Federal Regulations Part 137 as an agricultural flight that was not operating on a flight plan. Day visual meteorological conditions prevailed at the time of the accident. The flight originated from an unknown location and an unknown time. The pilot stated that he entered a field to be sprayed and about 100-120 ft agl, the low rotor rpm annunciation sounded. As he attempted to recover rotor rpm, the rpm continued to decay rapidly. He then used the remaining rotor rpm to cushion a landing onto the field. As the helicopter touched down, it slid about 150-200 ft before the skid dug into soft dirt and the helicopter rolled over. Post-accident examination of the engine by the operator revealed that the no. 6 cylinder had more leakage/lower compression than the previous 100-hour recorded compression checks. At the previous recorded compression check, the no. 6 cylinder had a 8.75% of leakage (73 psi held from a reference of 80 psi). The no. 6 cylinder had 35% leakage (52 psi held from a reference of 80 psi) during the examination. No further examination of the cylinder was performed. ## Aircraft - Registration: [N440EM](https://openairdocs.org/deregistered/N440EM-2020-11-13), registration cancelled 2020-11-13, S/N 13503, built 2013 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY 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-AE1A5](https://openairdocs.org/engine/lycoming-io-540-ae1a5) (registry code 41899, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 13503 - Year built: 2013 - Airframe hours: 588.3 - Engines: Lycoming IO-540-AE1AB 205 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Wallin Agricultural Aviation - Registered owner: Individual - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, April 23, 2017 - Departed: Lyons, NE - Destination: Lyons, NE ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 29; injuries: minor; flight instructor, airline transport; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review October 27, 2018; seat: right; restraint: lap only; flight hours: 2,750 total, 669 in this make and model, 1,675 as pilot in command, 107 in the last 90 days, 63 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 61 °F - Altimeter: 30.04 inHg - Observed at: TQE, 17 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 20190803013249A](https://openairdocs.org/incident/20190803013249A), Aug 3, 2019: Robinson Helicopter Company R44 II, Lyons, NE, Substantial damage. Engine started running rough during aerial application. Rotorcraft couldn't sustain enough power for normal flight and pilot initiated an emergency landing.… ## Docket (4 files) The files NTSB released with the investigation on October 17, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99989. 79.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 15.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11354879&FileExtension=pdf&FileName=NTSB%20Form%206120%20(003)_Redacted-Rel.pdf - Record of correspondence - pilot (item 2, PDF, 1 page, 82 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11366229&FileExtension=pdf&FileName=RECORD%20OF%20CORRESPONDENCE%20Pilot-Rel.pdf - Aircraft logs (item 3, PDF, 20 pages, 43.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11356049&FileExtension=pdf&FileName=Aircraft%20Logs%20Redacted-Rel.pdf - Aircraft weight and balance (item 4, PDF, 2 pages, 19.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11365686&FileExtension=pdf&FileName=Weight%20and%20Balance_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.