# NTSB MIA00LA134: Hiller UH-12C, N301CH, Lakeland, FL, April 15, 2000 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 15, 2000, 10:30 local (14:30 UTC) - Place: Lakeland, FL - Coordinates: 27.970167, -81.939926 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=27.9702&lon=-81.9399&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report January 18, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 48964 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA00LA134 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/48964/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=48964 - Page: https://openairdocs.org/ntsb/MIA00LA134 ## Probable cause The disconnection of the tail rotor drive shaft and subsequent lack of tail rotor control. Contributing factors were the worn drive shaft splines and the pilots' failure to apply collective on the touchdown resulting in a hard landing and subsequent roll over. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, hover - in ground effect - rotor drive system,tail rotor drive shaft - disconnected (cause) - miscellaneous,airframe - worn (contributing factor) - Loss of control - in flight, hover - in ground effect - tail rotor/anti-torque control - not available - Hard landing, landing - collective - not used, pilot in command (contributing factor) - Roll over, landing - flare/touchdown ## Analysis The pilot was hovering to parking when the helicopter experienced a failure of the tail rotor drive shaft. The pilot attempted a hovering autorotation, hovering he did not apply collective pitch. The helicopter collided with the ground in a right skid low condition and rolled over on its right side. Examination of the tailrotor drive shaft revealed excessive wear on the splines to the upper U-joint and on the splines of the transmission output shaft. ## Factual narrative On April 15, 2000, at about 1030 eastern daylight time, a Hiller UH-12C, N301CH, registered to a private owner, operating as a 14 CFR Part 91 personal flight, crashed after experiencing a loss of tail rotor control while hovering to park at the Lakeland-Linder Regional Airport, Lakeland, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The private pilot reported minor injuries. The helicopter sustained substantial damage. The flight originated from Plant City, Florida, about 15 minutes before the accident. The pilot stated he had just landed and was cleared to parking. While hovering at 4 feet, he made a right antitorque pedal turn. He applied left antitorque pedal to stop the turn and the helicopter continued to yaw to the right. He applied left antitorque pedal and closed the throttle. He did not pull collective pitch. The helicopter collided with the ground in a right skid low condition and rolled over on its right side. Examination of the helicopter revealed the tailrotor drive shaft was disconnected from the output spline shaft of the main transmission. The drive shaft was removed from the lower U-joint (Carden joint). One bolt was missing from the attachment of lower joint flange. The splines inside the upper U-joint were extensively worn, to the point of being non existent from the forward end to about 1 inch inside the fork. There was also excessive wear on the splines of the transmission output shaft. For additional information see FAA Aviation Safety Inspector statement. ## Aircraft - Registration: N301CH (not matched to a registry record) - Reported make and model: Hiller UH-12C - Category: Helicopter - Engines: unknown - Damage: Substantial damage - Fire: Unknown - Flight: Personal, Part 91 - Operator: Kenneth L. Grimes - Departed: TCM, PLANT CITY, FL - Destination: LAL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; medical: unknown, unknown ## Weather - Conditions: Visual (VMC), Not reported - Wind: 180° at 6 knots - Visibility: 12 statute miles - Lowest ceiling: 6,000 ft overcast - Temperature: 75 °F, dew point 70 °F - Altimeter: 30.00 inHg - Observed at: LAL ## 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 20000415007079A](https://openairdocs.org/incident/20000415007079A), Apr 15, 2000: Lakeland, FL, No damage. (-23) While in hover, tail potor drive shaft became disconnected from drive quill of main transmission due to excessive wear in upper drive shaft-joint… ## Docket (2 files) The files NTSB released with the investigation on August 21, 2000, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=48964. 528 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2 (item 1, .PDF, 458 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40386621&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1%2F2-Redacted.PDF - Reports from Federal Agencies (FAA Inspector Statement) (item 2, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40386622&FileExtension=.PDF&FileName=Reports%20from%20Federal%20Agencies%20(FAA%20Inspector%20Statement)-Redacted.PDF 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.