# NTSB MIA98LA161: Revolution MINI-500, N355RM, Villa Rica, GA, May 13, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 13, 1998, 16:30 local (20:30 UTC) - Place: Villa Rica, GA - Coordinates: 33.729946, -84.920608 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.7299&lon=-84.9206&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 26, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 38519 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA98LA161 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38519/pdf - Page: https://openairdocs.org/ntsb/MIA98LA161 ## Probable cause The pilot's choice of landing area during a precautionary landing adjacent to the runway. This resulted in an in-flight collision of the left skid with a rock during a cyclic flare, loss of directional control, and subsequent collision of the main rotor blade with the tail boom. ## Analysis The pilot stated that while in cruise flight he experienced a vibration/buzz sound. He set up for a precautionary, run-on landing to the nearest airport's single runway. When he realized the runway was in use, he elected to land onto an adjacent, grassy area. The left skid collided with a rock, the helicopter experienced a loss of directional control, yawed counterclockwise, and the main rotor blade severed the tailboom. ## Factual narrative On May 13, 1998, about 1630 eastern daylight time, a homebuilt helicopter, a Revolution Mini-500, N355RM, registered to a private individual, operating as a 14 CFR Part 91 personal flight, crashed during a precautionary landing at Stockmar Airport, Villa Rica, Georgia. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter received substantial damage, and the ATP-rated pilot was not injured. The flight originated from a private helipad at Cedartown, Georgia, about 45 minutes before the accident. The pilot stated that while in cruise flight, he noticed a "high frequency vibration/buzz sound," together with increasing coolant and exhaust gas temperatures, and elected to land. His intention was to perform a run-on, precautionary landing onto the single runway at Stockmar Airport, but the runway was in use, and he used a grassy area adjacent to the runway. The pilot further stated he chose the grassy area because it appeared to have been newly "bush-hogged"; however, while in the landing flare, he realized too late that the mowed level of the grass was high enough to conceal small obstructions. The left landing skid collided with a large, partially hidden rock and the helicopter rotated counterclockwise abruptly about its vertical axis approximately 240 degrees. During the ground gyration, the main rotor severed the tailboom and the tail rotor assembly separated from the helicopter. Postcrash inspection of the aircraft revealed that less than a full quantity of engine coolant was contained in the reservoir. The pilot stated the cooling system is a closed system, and he is at a loss to explain the leakage. He states, "It should be noted that prior to flight on this date, (accident date) the aircraft was parked inside a hangar on a concrete floor at 7GA9, (Whitesburg, Georgia) and no visible evidence of a leak was noted on the floor. Further, the aircraft was landed on a concrete pad at the private residence at Cedartown, GA and no visible evidence of a water leak was noted on the concrete pad." ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, cruise - airframe - vibration - cooling system - leak - In flight collision with object, landing - flare/touchdown - precautionary landing - attempted, pilot in command - unsuitable terrain or takeoff/landing/taxi area - selected, pilot in command (cause) - terrain condition - grass - terrain condition - rock(s)/boulder(s) (contributing factor) ## Aircraft - Registration: [N355RM](https://openairdocs.org/deregistered/N355RM-1998-10-31), registration cancelled 1998-10-31, S/N 0305 (OpenAirDocs) - Reported make and model: REVOLUTION MINI-500 - Registry model: [Moon Roy O REVLTN HELI MINI-500](https://openairdocs.org/model/moon-roy-o-revltn-heli-mini-500) (registry code 056043E) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 0305 - Airframe hours: 49 - Engines: Bombardier 582 67 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Roy Moon - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, January 21, 1998, 49 hours before - Departed: CEDARTOWN, GA - Destination: 7GA9, WHITESBURG, GA - Airport: Stockmar ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; airline transport, flight engineer, flight instructor; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 7,200 total, 55 in this make and model, 7,000 as pilot in command, 80 in the last 90 days, 18 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 88 °F, dew point 63 °F - Altimeter: 30.00 inHg - Observed at: ATL, 28 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 19980513009059A](https://openairdocs.org/incident/19980513009059A), May 13, 1998: Amtr MINI500, Villa Rica, GA, Substantial damage. Engine problem indications. Tried run on landing on runway but blocked by traffic. Hit rocks landing off runway. (.4)the pilot stated that while in cruise… 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.