# NTSB NYC98LA172: Ekstrom-Farrington Twinstar, N72DE, Paducah, KY, August 25, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 25, 1998, 16:00 local (21:00 UTC) - Place: Paducah, KY - Coordinates: 37.070209, -88.630584 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.0702&lon=-88.6306&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 28, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 43828 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC98LA172 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43828/pdf - Page: https://openairdocs.org/ntsb/NYC98LA172 ## Probable cause Failure of a through-bolt that attached the lateral control arms to the yoke assembly, due to unanticipated rotor brake forces through the flight control system. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, approach - vfr pattern - final approach - miscellaneous,bolt/nut/fastener/clamp/spring - failure (cause) - acft/equip,inadequate design, kit manufacturer (cause) - rotorcraft flight control,pitch change horn - separation - Loss of control - in flight, approach - vfr pattern - final approach - aircraft control - not possible, pilot in command - In flight collision with terrain/water, descent - uncontrolled - terrain condition - grass ## Analysis The gyroplane was on short final, about 15 feet above the ground, when it went into an uncommanded right turn and right roll. The heading changed 180 degrees, and the gyroplane impacted sod near the runway threshold. The gyroplane had a rotor brake mechanism which was activated by pushing the cyclic control full forward. A through-bolt which had attached the two lateral control arms to the yoke assembly, was discovered missing, and the right lateral control arm had separated from the yoke assembly. The kit manufacturer was considering implementing a clamp-type rotor brake system, much like a bicycle's, to prevent rotor brake forces from passing through the flight control system. ## Factual narrative On August 25, 1998, about 1600 Central Daylight Time, a homebuilt Twinstar gyroplane, N72DE, was substantially damaged during landing at Farrington Airpark (FIO), Paducah, Kentucky. The certificated private pilot was uninjured, and visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the local instructional flight, conducted under 14 CFR Part 91. According to the pilot, the gyroplane was on short final, about 15 feet above the ground, when it went into an uncommanded right turn and right roll. The heading changed 180 degrees, and the gyroplane impacted sod near the runway threshold. A Federal Aviation Administration (FAA) Inspector examined the wreckage. He reported that a through-bolt (AN type), which had attached the two lateral control arms to the yoke assembly, was missing, and that the right lateral control arm had separated from the yoke assembly. Additionally, no maintenance work had been performed just prior to the accident. The inspector also noted that the gyroplane had a rotor brake mechanism which was activated by pushing the cyclic control full forward. The president of the company that owned the accident gyroplane, as well as manufactured the Twinstar kits, stated that the missing bolt could not be found. He also checked the rotor system after the accident, and noted no blade damage that might have been caused by a bolt passing through it. He said that the bolt may have failed through repetitive use of the rotor brake over a long period of time, or through one heavy application of the rotor brake. He felt that normal use of the rotor brake should have produced less stress on the bolt than would normal flight operations. He also noted that the rotor head had been off and on several times, and raised the possibility that the bolt could have been overtorqued. The president stated that he sent an advisory to other kit owners to check the bolts, and that he was considering implementing a clamp-type rotor brake system, much like a bicycle's, to prevent rotor brake forces from going through the flight control system. ## Aircraft - Registration: [N72DE](https://openairdocs.org/aircraft/N72DE), registered now, S/N 001, built 1990 (OpenAirDocs) - Reported make and model: Ekstrom-Farrington TWINSTAR - Registry model: [Ekstrom Dave TWINSTARR](https://openairdocs.org/model/ekstrom-dave-twinstarr) (registry code 13015DF) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Gyroplane, amateur-built - Serial number: 001 - Airframe hours: 937 - Engines: Continental O-320-A2B 100 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Farrington Aircraft Corp. - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Unknown, August 13, 1998, 20 hours before - Departed: FIO - Airport: FIO, Farrington Airpark, runway 22, 2,915 × 60 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; private; airplane ratings: single-engine land, single-engine sea; medical: class 2, valid medical--w/ waivers/lim; seat: front; flight hours: 168 total, 14 in this make and model, 71 as pilot in command, 14 in the last 90 days, 14 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 93 °F, dew point 73 °F - Altimeter: 29.00 inHg - Observed at: PAH, 20 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 19980825021859A](https://openairdocs.org/incident/19980825021859A), Aug 25, 1998: Amtr TWINSTAR, Paducah, KY, Substantial damage. Acft crashed on landing under unknown circumstances. (-23) on August 25, 1998, at approximately 1600 CDT, an experimental-amateur built, twin-star gyroplane,… 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.