# NTSB IAD97LA104: Bell 47G-3B-1, N35134, Mt. Vernon, OH, July 26, 1997 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 26, 1997, 17:10 local (21:10 UTC) - Place: Mt. Vernon, OH - Coordinates: 40.390651, -82.469184 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.3907&lon=-82.4692&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 4 minor, 3 uninjured; on the ground: 4 minor - Status: Completed, report June 9, 1999 - Report: Approved by Office Director - NTSB case key (mKey): 28219 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=IAD97LA104 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/28219/pdf - Page: https://openairdocs.org/ntsb/IAD97LA104 ## Probable cause The pilot's failure to maintain rotor RPM. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, takeoff - initial climb - rotor rpm - not maintained, pilot in command (cause) - Forced landing, emergency descent/landing - Hard landing, descent - emergency ## Analysis The pilot was flying passengers for 5 minute sightseeing tours. Shortly after departing with two passengers and while at 75 feet AGL, the pilot stated that he experienced an unexplained loss of RPM. The pilot reversed course using right pedal to turn back to the point of departure. While maneuvering to avoid obstacles and with a tailwind, the pilot stated that the rotor RPM further decayed. The helicopter impacted the ground hard, and the main rotor blade severed the tail boom. No mechanical problems were reported by the pilot, nor was any fuel contamination found. A Federal Aviation Administration Inspector started the engine twice without finding any mechanical malfunctions. ## Factual narrative On July 26, 1997, about 1710 eastern daylight time, a Bell 47G-3B-1, N35134, was substantially damaged as it impacted the ground during a forced landing at the Knox County Fairground, Mt. Vernon, Ohio. The certificated commercial pilot and two passengers were not injured. Four people on the ground received minor injuries when struck by flying debris. Visual meteorological conditions prevailed and no flight plan was filed for the sightseeing flight conducted under 14 CFR Part 91. The pilot was taking passengers for 5 minute flights from the County Fairgrounds. The pilot stated that with two passengers onboard, he reached approximately 75 to 100 feet AGL, when the helicopter experienced "an unexplained loss of RPM." Unable to clear obstacles in his departure path, the pilot initiated a 180 degree right pedal turn back to his point of departure. The pilot stated that obstacles near the landing pad required him to stay high and "a tailwind caused the rotor RPM to further decay." Witnesses stated that the helicopter impacted the ground hard, and the main rotor blades severed the tail boom. On July 28, 1997, a Federal Aviation Administration (FAA) Inspector examined the wreckage. He stated that the fuel sumps were drained and no signs of contamination was found, and the fuel tank vent passages were unobstructed. The helicopter company's chief pilot stated to the FAA Inspector that the helicopter lost rotor blade power shortly after lift off and out of ground effect, but the pilot did not report any engine malfunction. The Inspector monitored two engine operations, but without rotor engagement due to rotor blade damage sustained during the accident. According to the Inspector, the engine was started twice, and magneto functional checks were performed with a "normal" RPM drop observed each time. ## Aircraft - Registration: [N35134](https://openairdocs.org/aircraft/N35134), registered now, S/N 3591 (OpenAirDocs) - Reported make and model: Bell 47G-3B-1 - Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs) - Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 3591 - Airframe hours: 6971 - Engines: Lycoming VO-435-A1F 220 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Registered owner: Green River Aviation Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 1, 1997, 40 hours before - Departed: NONE, KNOX CNTY FAIR, OH - Destination: NONE ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 27; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 553 total, 242 in this make and model, 400 as pilot in command, 130 in the last 90 days, 9 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 12 knots, gusting 17 - Visibility: 3.5 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 79 °F - Altimeter: 29.00 inHg - Observed at: MFD, 30 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 19970726025799A](https://openairdocs.org/incident/19970726025799A), Jul 26, 1997: Bell 47G3B1, Mt Vernon, OH, Substantial damage. Lost power on climbout. Turned back to land. During landing main rotors hit tailboom. Indicates hard landing. (-23) the pilot stated that on July 26, 1997, at… 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.