# NTSB LAX95LA326: Hiller UH-12C, N1348Z, Porterville, CA, September 6, 1995 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: September 6, 1995, 09:06 local (16:06 UTC) - Place: Porterville, CA - Coordinates: 35.95951, -118.920219 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.9595&lon=-118.9202&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report March 21, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 29211 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX95LA326 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29211/pdf - Page: https://openairdocs.org/ntsb/LAX95LA326 ## Probable cause the flight instructor's inadequate supervision of the flight; the dual student's improper use of the flight controls; and improper remedial action. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, hover - supervision - inadequate, pilot in command(cfi) (cause) - flight controls - improper use of, dual student (cause) - remedial action - improper, dual student (cause) - loss of tail rotor effectiveness - inadvertent, pilot in command(cfi) - Forced landing, descent - emergency - Hard landing, descent - emergency ## Analysis THE DUAL STUDENT ATTEMPTED TO RAISE THE HELICOPTER TO A HOVER AND INADVERTENTLY APPLIED AFT CYCLIC. THE HELICOPTER BEGAN TO MOVE REARWARD AND THE DUAL STUDENT ABRUPTLY RAISED THE COLLECTIVE TO CORRECT THIS CONDITION. THE HELICOPTER CLIMBED TO 18 FEET ABOVE THE GROUND AND THE MAIN ROTOR RPM BEGAN TO DECAY. THE CFI ASSUMED CONTROL OF THE HELICOPTER AND LOWERED THE COLLECTIVE TO REGAIN MAIN ROTOR RPM, BUT WITHOUT SUCCESS. THE CFI THEN EXECUTED AN AUTOROTATION, BUT DUE TO THE DECAYING MAIN ROTOR RPM SUSTAINED A HARD LANDING. THE HELICOPTER DID NOT EXPERIENCE ANY PREIMPACT MALFUNCTIONS OF FAILURES. ## Factual narrative On September 6, 1995, at 0906 hours Pacific daylight time, a Hiller UH-12C helicopter, N1348Z, sustained a hard landing at Porterville Municipal Airport, Porterville, California. The pilots were conducting a local visual flight rules instructional flight. The helicopter, operated by Whirlybirds, Inc., Concord, California, sustained substantial damage. The certificated commercial pilot/flight instructor (CFI), and the certificated private pilot/dual student received minor injuries. Visual meteorological conditions prevailed. The flight originated at Porterville Municipal Airport, at 0830 hours. The CFI reported in a telephone interview conducted on September 7, 1995, that before the accident the dual student was practicing some maneuvers and had landed. During the lift-off, the helicopter began to drift backwards. The dual student immediately applied "full up collective," the helicopter continued to go backwards, and rapidly raised about 15 to 18 feet above the ground. The CFI immediately assumed the flight controls and applied full throttle. This action did not arrest the decaying main rotor rpm. The CFI simultaneously attempted to regain the main rotor rpm by trying to "milk down the collective," but was unsuccessful. During this process, the helicopter descended to 10 feet above the ground. Due to the decaying main rotor rpm, the helicopter experienced a loss of tail rotor effectiveness. The CFI then elected to execute a hovering autorotation. He was unable to cushion the landing due to the low main rotor rpm and the helicopter sustained a hard landing. The CFI reiterated this telephone statement in the Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2. He indicated in the form that the helicopter did not experience any preimpact malfunctions or failures. ## Aircraft - Registration: [N1348Z](https://openairdocs.org/aircraft/N1348Z), registered now, S/N 1043, built 1958 (OpenAirDocs) - Reported make and model: HILLER UH-12C - Registry model: [Hiller UH-12C](https://openairdocs.org/model/hiller-uh-12c) (registry code 4360116) (OpenAirDocs) - Registry engine: [Franklin 6V4 series](https://openairdocs.org/engine/franklin-6v4-series) (registry code 27033, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 1042 - Airframe hours: 3592 - Engines: FRANKLIN 6V350B 235 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Whirlybirds, Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 16, 1995, 80 hours before - Departed: PTV - Airport: PTV, Porterville Municipal ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; commercial; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 626 total, 78 in this make and model, 574 as pilot in command, 59 in the last 90 days, 25 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 54 °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 19950906027929A](https://openairdocs.org/incident/19950906027929A), Sep 6, 1995: Hiller UH12C, Porterville, CA, Substantial damage. Drifted backwards after liftoff. Lifted collective. Rotor RPM lost. CFI attempted recovery too late. Hard impact. ## Other investigations on N1348Z (1) 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 LAX95LA238](https://openairdocs.org/ntsb/LAX95LA238), Jul 3, 1995: Hiller UH-12C (N1348Z), Rio Vista, CA, substantial damage. Probable cause: The result of a chafing failure of the left anti-torque control cable while the aircraft was in flight. An inadequate preflight inspection by the pilot-in-command, and an inadequate 100-hour… 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.