# NTSB FTW95LA230: Hiller UH-12E, N4254X, Checotah, OK, June 4, 1995 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: June 4, 1995, 18:00 local (23:00 UTC) - Place: Checotah, OK - Coordinates: 35.469566, -95.51966 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.4696&lon=-95.5197&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report October 27, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 19443 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW95LA230 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/19443/pdf - Page: https://openairdocs.org/ntsb/FTW95LA230 ## Probable cause THE PILOT ALLOWING THE HELICOPTER TO TOUCHDOWN IMPROPERLY. A FACTOR WAS THE ERRATIC RUNNING ENGINE. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - aerial application - engine assembly - erratic (contributing factor) - reason for occurrence undetermined - Forced landing, descent - emergency - Hard landing, descent - emergency - terrain condition - wet - run on landing - attempted, pilot in command - touchdown - improper, pilot in command (cause) - landing gear,skid assembly - separation ## Analysis WHILE DISPENSING A HERBICIDE, 'THE ENGINE LOST POWER, RPM, AND A VIBRATION WAS FELT. THE ENGINE RECOVERED TO FULL POWER CAUSING THE HELICOPTER TO YAW.' THIS EVENT OCCURRED THREE ADDITIONAL TIMES FOR UNDETERMINED REASONS DURING AN ATTEMPTED RUN-ON LANDING TO A FIELD. AS THE HELICOPTER'S SKIDS CONTACTED THE GROUND, THE PILOT HEARD A 'BOOM', THE HELICOPTER YAWED, THE SKIDS SEPARATED FROM THE FUSELAGE, AND THE HELICOPTER CAME TO REST ON ITS SIDE. ## Factual narrative On June 4, 1995, at 1800 central daylight time, a Hiller UH-12E helicopter, N4254X, was substantially damaged during a forced landing near Checotah, Oklahoma. The airline transport rated pilot received minor injuries. The helicopter was being operated by Main Street Aviation under Title 14 CFR Part 137. Visual meteorological conditions prevailed and no flight plan was filed. On the enclosed Pilot/Operator Report, the pilot reported the following information. While dispensing a herbicide, "the engine lost power, RPM, and a vibration was felt. The engine recovered to full power causing the helicopter to yaw." This event occurred three additional times during an attempted run-on landing to a field. As the helicopter's skids contacted the ground, the pilot heard a "boom", the helicopter yawed, and the skids separated from the fuselage. During the ensuing landing, the helicopter came to rest on it's side. The pilot reported to the investigator-in-charge, that an examination of the helicopter revealed the following additional damage. The tail rotor gear box was separated from the tailboom, and the first section of the tail rotor drive shaft was separated from the drive shaft and main transmission. He further reported that the reason for the erratic running engine had not been determined. ## Aircraft - Registration: [N4254X](https://openairdocs.org/deregistered/N4254X-2015-05-15), registration cancelled 2015-05-15, S/N 1378, built 1962 (OpenAirDocs) - Reported make and model: HILLER UH-12E - Registry model: [Hiller UH-12D](https://openairdocs.org/model/hiller-uh-12d) (registry code 4360118) (OpenAirDocs) - Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 1378 - Airframe hours: 6183 - Engines: LYCOMING VO-540-B1A 305 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Main Street Aviation, Inc - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, March 23, 1995, 21 hours before - Departed: NONE ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: center; flight hours: 1,673 total, 508 in this make and model, 1,252 as pilot in command, 21 in the last 90 days, 7 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 4 knots, gusting 6 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 61 °F - Altimeter: 29.00 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 19950604014509A](https://openairdocs.org/incident/19950604014509A), Jun 4, 1995: Hiller UH12E, Checotah, OK, Substantial damage. Erratic engine surging on spray run. Caused yaw during attempted run on landing. Separated skids and tail rotor. 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.