# NTSB ERA21LA335: Hummer 260L, N777TC, Livingston, TN, August 18, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: August 18, 2021, 18:50 local (23:50 UTC) - Place: Livingston, TN - Coordinates: 36.416973, -85.30512 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.4170&lon=-85.3051&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 103738 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA21LA335 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103738/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103738 - Page: https://openairdocs.org/ntsb/ERA21LA335 ## Probable cause A total loss of engine power for reasons that could not be determined. Contributing to the accident was the pilot’s operation of the helicopter in a flight regime that would not allow for a successful autorotative landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=05637XV), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=05637XV), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=05637XV), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05637XV), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05637XV), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-flare/touchdown: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-events/092/sequence.md?model=05637XV), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) - [Landing-flare/touchdown: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Cook Timothy HUMMER 260L, 1 case](https://openairdocs.org/ntsb-events/097/sequence.md?model=05637XV), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) ## Analysis The pilot initiated takeoff in the helicopter, and when passing through effective translational lift, with an airspeed between 40 and 50 knots, and about 100 to 150 ft above ground level (agl), the engine experienced a sudden complete loss of power. He lowered the collective, made a partial throttle reduction, and entered an autorotation, but engine power increased when the helicopter was at 70 to 75 ft agl and 50 knots. He increased the throttle, and the engine power increased to full rpm. As he increased collective, the engine “sputtered and quit instantly.” The helicopter was operating in the shaded area of the helicopter’s height/velocity diagram, which, according to guidance, may not allow sufficient time or altitude to enter a stabilized autorotative descent. Although the pilot rapidly lowered the collective to gain energy in the main rotor blades, there was not enough inertia in them for a normal autorotative landing. The helicopter landed hard on soft wet terrain resulting in structural damage to one of the steel tubes that attached the tailboom. During postaccident examination of the helicopter and its engine, one fuel injector nozzle flowed slightly less than the other five; however, it likely did not contribute to the twice-repeated total loss of engine power. The examination of the engine and its systems revealed no other evidence of preimpact failure or malfunction. The reason for the twice-repeated total loss of engine power could not be determined based on the available evidence. ## Factual narrative On August 18, 2021, about 1850 central daylight time, an experimental, amateur-built Hummer 260L helicopter, N777TC, was substantially damaged when it was involved in an accident near Livingston, Tennessee. The private pilot and the pilot-rated passenger were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot/owner stated that the flight was initiated from Livingston Municipal Airport (8A3) with an adequate supply of fuel. After warming the engine, he lifted the helicopter to a hover, hover taxied, ground taxied, and practiced setting down and lifting-up to a hover for about 10 to 15 minutes with no engine issues noted. He then intended to takeoff and fly in the airport traffic pattern. The pilot reported that the auxiliary fuel pump was on for the takeoff. He started to takeoff, and between 100 to 150 ft above ground level (agl) while passing through effective translational lift at an airspeed between 40 and 50 knots, the helicopter experienced a sudden complete loss of engine power. The pilot lowered the collective, made a partial throttle reduction, and entered an autorotation. When the helicopter was at 70 to 75 ft agl and 50 knots, the engine power increased. The pilot increased the throttle, and the engine power increased to full rpm; but as he increased collective, the engine again lost total power. According to the pilot, the helicopter was operating in the shaded area of the helicopter’s height/velocity diagram, and although he rapidly lowered the collective to gain energy in the main rotor blades, there was not enough inertia in them for a normal autorotative landing. The helicopter impacted hard on soft, wet, and slightly sloped terrain, and the landing gear wheels became buried and separated. The helicopter then rolled onto its right side, and the main rotor blades contacted the ground. The pilot stated that during recovery of the helicopter, fuel drained from a depressed fuel tank sump drain valve. After recovering the helicopter and elevating it, an additional 4 to 5 gallons of fuel were drained, which emptied the fuel tank; no fuel contamination was reported. One of four 4130 steel tubes that structurally secured the tailboom was cracked and deformed. The fuel shut-off valve was in the open position. Examination of the engine following recovery revealed that all fuel hoses were installed correctly and tight. Residual fuel was present in each hose. Residual fuel and some debris was present in the airframe fuel strainer; the debris was sand-like in particle size. The inlet screen of the controller, or servo fuel injector, was clean. There were no discrepancies found with the engine controls, the air induction, exhaust, and ignition systems, or the auxiliary fuel pump, which was electrically tested. Crankshaft, camshaft, and valve train continuity were confirmed. Borescope inspection of each cylinder revealed no discrepancies with the valves or pistons. Operationaltesting of the fuel injector nozzles revealed an equal amount flowed from five of the six fuel injector nozzles; the No. 3 nozzle’s flow was about two-thirds that of the others. The controller was retained and sent to the manufacturer’s facility for operational testing, which revealed no evidence of preimpact failure or malfunction. The unit was operationally tested with airflow and found to flow nearly identical to the values that were recorded when it was manufactured in 2012. According to the Federal Aviation Administration’s Helicopter Flying Handbook, the height/velocity (H/V) diagram shows the combinations of airspeed and height above the ground that will allow an average pilot to successfully complete a landing after an engine failure. The handbook states that operation of the helicopter in the shaded area of the diagram may not allow sufficient time or altitude to enter a stabilized autorotative descent. It further states that “in the simplest explanation, the H/V diagram is a diagram in which the shaded areas should be avoided, as the pilot may be unable to complete an autorotation landing without damage.” ## Aircraft - Registration: [N777TC](https://openairdocs.org/aircraft/N777TC), registered now, S/N 0834, built 2018 (OpenAirDocs) - Reported make and model: Hummer 260L (NO SERIES) - Registry model: [Cook Timothy HUMMER 260L](https://openairdocs.org/model/cook-timothy-hummer-260l) (registry code 05637XV) (OpenAirDocs) - Registry engine: [Lycoming VO-435-A1F](https://openairdocs.org/engine/lycoming-vo-435-a1f) (registry code 42200, reciprocating) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 0834 - Year built: 2018 - Airframe hours: 117 - Engines: Lycoming VIO-435-A1F 260 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, December 21, 2020, 4 hours before - Airport: 8A3, Livingston Municipal Airport - Equipment: Electronic primary flight display, Electronic multifunction display, Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; injuries: none; private; airplane ratings: single-engine land, single-engine sea; medical: class 3, with waivers/limitations; last flight review December 31, 2019; seat: right; restraint: 4-point; flight hours: 780 total, 135 in this make and model, 650 as pilot in command - Pilot-rated passenger; age 73; injuries: none; airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; seat: left; restraint: 4-point; flight hours: 30,000 total ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: 10,000 ft broken - Temperature: 75 °F, dew point 73 °F - Altimeter: 30.14 inHg - Observed at: SRB, 24 nm away - METAR: METAR KSRB 182355Z AUTO 00000KT 10SM BKN100 24/23 A3014 RMK A01= ## 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 20210818014409A](https://openairdocs.org/incident/20210818014409A), Aug 18, 2021: Cook Timothy HUMMER 260L, Livingston, TN, Substantial damage. Aircraft departed 8A3 to the north. The aircraft accelerated through etl and began its departure climb. At approximately 100 ft AGL the engine quit. Pilot… ## Docket (9 files) The files NTSB released with the investigation on July 26, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103738. 20.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 10.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12854186&FileExtension=pdf&FileName=6120%20Received%2010%2019%202021_ERA21LA335_Redacted-Rel.pdf - Passenger statement (item 2, PDF, 1 page, 140 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14924303&FileExtension=pdf&FileName=Passenger%20Statement_Redacted-Rel.pdf - Record of NTSB conversations (item 3, PDF, 6 pages, 1 photo, 393 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14932652&FileExtension=pdf&FileName=Record%20of%20NTSB%20Conversations_Redacted-Rel.pdf - Memorandum for record - additional information from pilot/owner of N777TC (item 4, PDF, 1 page, 114 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14924671&FileExtension=pdf&FileName=Memo%20For%20Record%20-Additional%20Information%20Fm%20Pilot%2012%201%202022-Rel.pdf - Statement from mechanic (item 5, PDF, 1 page, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14924768&FileExtension=pdf&FileName=Mechanic%20Statement%20Recd%2012%208%202022_Redacted-Rel.pdf - Height velocity diagram (item 6, PDF, 1 page, 913 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14934899&FileExtension=pdf&FileName=Height%20Velocity%20Diagram-Rel.pdf - Memorandum for record - controller examination and operational testing (item 7, PDF, 2 pages, 1 photo, 211 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14935008&FileExtension=pdf&FileName=Memo%20For%20Record%20-Controller%20Examination-Rel.pdf - Investigative photographs (item 8, PDF, 3 pages, 3 photos, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14934662&FileExtension=pdf&FileName=Investigative%20Photographs_ERA21LA335-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15, and NTSB evidence control form (item 9, PDF, 2 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14939739&FileExtension=pdf&FileName=Wreckage%20Release%20%26%20ECF_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.