# NTSB FTW98LA400: Bell 47-G-2, N1575, Ardmore, OK, September 17, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 17, 1998, 09:15 local (14:15 UTC) - Place: Ardmore, OK - Coordinates: 34.190227, -97.110504 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.1902&lon=-97.1105&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 15, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 43956 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW98LA400 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43956/pdf - Page: https://openairdocs.org/ntsb/FTW98LA400 ## Probable cause The pilots failure to maintain clearance with terrain and the ensuing loss of control. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, landing - terrain condition - grass (contributing factor) - clearance - not obtained/maintained, pilot in command (cause) - Loss of control - in flight, hover - directional control - not obtained/maintained, pilot in command (cause) - Roll over, descent - uncontrolled ## Analysis The solo student pilot lost control of the aircraft after the tail rotor contacted the ground. Witnesses to the accident saw the aircraft spin around to the right after the tail rotor hit the ground. When the student pilot attempted to set the aircraft back down, the helicopter rolled on to its side. The winds at the time of the accident were reported to be calm. ## Factual narrative On September 17, 1998, at 0915 central daylight time, a Bell 47-G-2 helicopter, N1575, was substantially damaged following a loss of control while hovering at the Ardmore Downtown Executive Airport near Ardmore, Oklahoma. The solo student pilot was not injured. The helicopter was owned and operated by Versatile Helicopters Inc., of Ardmore, Oklahoma. Visual meteorological conditions prevailed and no flight plan was filed for the Title 14 CFR Part 91 local training flight which originated at 0825. During an interview conducted by the FAA inspector, the operator of the helicopter said that during a takeoff to hover, the heals of the skids "sunk into the sod and brought the aircraft back, striking the tail rotor blades on the ground." The operator added that "one of the tail rotor blades departed the hub." The pilot stated that after the tail rotor hit, the helicopter "raised off the ground and started spinning to the right." The student pilot added that he, "attempted to level the helicopter by lowering the collective to bring the helicopter to the ground." The helicopter "hit the ground with the left skid and rolled over on to its left side." Winds at the time of the accident were reported to be calm. Examination of the aircraft by the FAA inspector revealed that the tailboom was destroyed, the cabin sustained structural damage and both main rotor blades were damaged. The student pilot had accumulated approximately 41 hours in the helicopter and was on his seventh solo flight at the time of the accident. ## Aircraft - Registration: [N1575](https://openairdocs.org/deregistered/N1575-2018-02-08), registration cancelled 2018-02-08, S/N 57 (OpenAirDocs) - Reported make and model: Bell 47-G-2 - Registry model: [Bell 47B3](https://openairdocs.org/model/bell-47b3) (registry code 1180606) (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: 57 - Airframe hours: 13948 - Engines: Lycoming VO-435-A1F 260 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Versatile Helicopters Inc. - Registered owner: Helicopter Spraying Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, September 8, 1998, 50 hours before - Departed: 1F0 - Airport: 1F0, Ardmore Downtown Executiv, runway 17, 5,000 × 75 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; student; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 41 total, 12 in this make and model, 4 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 50° at 4 knots - Visibility: 3 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 72 °F - Altimeter: 30.00 inHg ## 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 19980917024909A](https://openairdocs.org/incident/19980917024909A), Sep 17, 1998: Bell 47G2, Ardmore, OK, Substantial damage. (.4) On September 17, 1998, at 0915 central daylight time, a Bell 47-G-2 helicopter, N1575, was substantially damaged following a loss of control while… ## Other investigations on N1575 (4) 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 DFW06CA055](https://openairdocs.org/ntsb/DFW06CA055), Jan 13, 2006: Bell 47-B3 (N1575), Dennison, TX, substantial damage. Probable cause: The in-flight separation of the stabilizer bar tube. - [NTSB FTW01LA087](https://openairdocs.org/ntsb/FTW01LA087), Mar 22, 2001: Bell 47G2 (N1575), Ardmore, OK, substantial damage. Probable cause: the loss of tail rotor control during maneuvering resultant from the failure of the tail rotor drive shaft coupling due to a stripped thread which allowed the grease lubricating the shaft to leak… - [NTSB CHI77FEC47](https://openairdocs.org/ntsb/CHI77FEC47), Sep 18, 1977: Bell 47B3 (N1575), Lake Orion, MI, substantial damage - [NTSB CHI70FDW10](https://openairdocs.org/ntsb/CHI70FDW10), Mar 27, 1970: Bell 47G (N1575), Port Huron, MI, 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.