# NTSB MIA96LA209: Hughes 269A, N8784F, Cottondale, FL, August 10, 1996 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 10, 1996, 14:25 local (19:25 UTC) - Place: Cottondale, FL - Coordinates: 30.790853, -85.369514 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=30.7909&lon=-85.3695&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor - Status: Completed, report February 1, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 38071 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA96LA209 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38071/pdf - Page: https://openairdocs.org/ntsb/MIA96LA209 ## Probable cause improper assembly of the main rotor blade dampners by a mechanic which resulted in the helicopter being damaged by ground resonance. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, hover - in ground effect - maintenance,rebuild/remanufacture - improper, company maintenance personnel (cause) - rotor system,rotor vibration absorber - failure,total (cause) - Airframe/component/system failure/malfunction, emergency landing - ground resonance - encountered ## Analysis The main rotor blade dampners had been overhauled just before the flight. After liftoff, the pilot began to feel severe vertical and lateral vibrations. He noticed that one rotor blade was tracking 12-18 inches out of the normal plane. As the pilot set the helicopter down, it began to come apart due to ground resonance. Examination of the main rotor blade dampners by an FAA inspector showed they had not been reassembled in accordance with the manufacturers maintenance manual. The maintenance manual stated that an improper assembly of the blade dampners could lead to ground resonance and destruction of the helicopter. ## Factual narrative On August 10, 1996, about 1425 central daylight time, a Hughes 269A, N8784F, registered to Joyride Ventures, Inc., crashed at the Helicopter Technologies facility, Cottondale, Florida, while on a Title 14 CFR Part 91 maintenance test flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The helicopter received substantial damage and the commercial-rated pilot received minor injuries. The passenger received serious injuries. The flight was originating at the time of the accident. The pilot stated the helicopter owner and his pilot had reported the helicopter had a tendency to make a uncommanded roll to the right. On run-up he checked the controls and found nothing unusual. As he lifted the aircraft to a 3 feet hover the aircraft started a vertical vibration which increased to a severe vertical vibration within seconds. The aircraft also started a lateral vibration which increased to a severe lateral vibration. He noticed that one of the blades appeared to jump 12-18 inches from the normal tip path plane. He felt that the helicopter was going to come apart and elected to set it back on the ground. As he set down with the vibration continuing, the helicopter started to come apart and rotate to the right. Review of maintenance records was conducted by an FAA inspector. Records showed the main rotor blade hydraulic friction dampners had been overhauled just before the test flight. Teardown examination of the dampners by an FAA inspector showed the dampners had not been reassembled in accordance with manufacturers maintenance instructions. The maintenance instructions state that improper assembly of the dampners could lead to conditions that could result in ground resonance and destruction of the helicopter. Examination of the helicopter by the FAA inspector showed the failure of the main rotor system and destruction of the helicopter was a result of ground resonance. (See attached FAA inspector statement.) ## Aircraft - Registration: [N8784F](https://openairdocs.org/deregistered/N8784F-1997-02-19), registration cancelled 1997-02-19, S/N 720110 (OpenAirDocs) - Reported make and model: Hughes 269A - Registry model: [Hughes 269A](https://openairdocs.org/model/hughes-269a) (registry code 4470402) (OpenAirDocs) - Category: Helicopter - Serial number: 72-0110 - Engines: Lycoming HIO-360-B1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Operator: Helicopter Technologies, Inc. - Registered owner: Joyride Ventures, Inc. - Airworthiness certificate: Standard, Normal - Airport: Helicopter Tech. Heliport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; commercial, flight instructor; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 8,554 total, 1,280 in this make and model, 8,340 as pilot in command, 32 in the last 90 days, 1 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 330° at 8 knots - Visibility: 7 statute miles - Lowest ceiling: 2,800 ft broken - Temperature: 81 °F, dew point 73 °F - Altimeter: 29.00 inHg - Observed at: TLH, 55 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 19960810022279A](https://openairdocs.org/incident/19960810022279A), Aug 10, 1996: Hughes 269A, Cottondale, FL, Substantial damage. Lifted on maintenance test flight vibration and rotor flapping. Crashed. Dampers had been improperly installed. ## Other investigations on N8784F (3) 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. - [NTSB LAX89LA127](https://openairdocs.org/ntsb/LAX89LA127), Mar 18, 1989: Hughes 269A (N8784F), Malibu, CA, no damage. Probable cause: THE FAILURE OF THE PASSENGER TO FOLLOW BRIEFED PROCEDURES AND THE FAILURE OF GROUND PERSONNEL TO PROVIDE ADEQUATE ASSISTANCE. - [NTSB UNK64X3704](https://openairdocs.org/ntsb/UNK64X3704), Aug 31, 1964: Hughes 269A (N8784F), Phoenix, AZ, destroyed - [NTSB UNK64X1150](https://openairdocs.org/ntsb/UNK64X1150), Apr 3, 1964: Hughes 269A (N8784F), Phoenix, AZ, substantial damage 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.